PDA

View Full Version : Accepted Comet Theory is Flawed.



dapted
2002-Mar-26, 04:42 AM
I find fault with generally accepted comet theory. The current theory goes something like this.
Comets are dirty snowballs which occasionally pass through our solar system. As they approach the sun, they go through a transformation as they move from the so-called inactive zone, to the active zone. The active zone is where they begin to display comet like appearance. The dirty snowball begins melting and outgassing a percentage of its mass. It develops a fog like shroud called a coma which is much larger than the comet itself. Sometimes much bigger than the earth itself. Even though the comet nucleus is only one to six miles long. The closer it gets to the sun the brighter it glows and the more material it outgasses. The solar wind which blows from the sun at speeds of 200 to 600 kilometers per hour blow much of the coma and outgassed material behind the comet in two tails. One is called the dust tail which falls behind the comets movement around the sun and leave a trail of debris behind. The other tail is called the Ion Tail and it allways points away from the sun. The Ion tail can be many millions of miles beyond the comet by the solar wind. But the Ion tail is allways pointing away from the sun and may actually be in front of the comets path as it exits its close call with the sun.

I have several problems with this theory. First of all as the comet gets close to the sun the tail moves around much like the indicator shadow on a sun dial. Looking at the pictures of the comet you can see what appears to be material flowing away from the comet and downstream from the sun. But at 10 million kilometers long, or 4 million miles long the far end of the tail must accelerate sideways across the apparent solar wind to maintain its position in time with the comet. Kind of like the speed of a wheel at its hub versus the speed of the wheel at the tire. The further out you go the faster the material making up the wheel must travel. In the case of a comet it moves relatively slowly, but the material streaming off the comet should maintain the same speed around the sun as the comet. But it obviously must speed up. But there is nothing to accelerate it across the apparent direction of the solar wind. If you have ever seen tracer rounds being shot at night you know that if you move the gun to the left or right while it is firing the path of the bullets appears to be an arc. Same thing is apparent if you squirt a water hose in your back yard. Even though the water mollecules are moving in a straight line, if you move the nozzle to the left or rignt the stream appears to be an arc. Even if the molecules from the comet are accelerated at 100% of the speed of the solar wind, (which is unlikely) it would take 5 hours for the ionizing material to make it to from the comet to the end of the tail. But it does not. It looks straight as an arrow. I have some very against the mainstream theories about what can cause this apparition. But none of them are perfect either. The Ion tail on the comet should look like an arc. Can anybody provide a reasonable explanation? I don't want to expose my theories until I have tried all other logical expanations.

Thanks, Dan Apted. dapted@customcpu.com

2002-Mar-26, 07:43 AM
<a name="20020326.1:3"> page 20020326.1:3 aka COMET's tail
On 2002-03-25 23:42, dapted wrote: To: 7 CABAN 15 CUMKU
8: March 26, 2002 Log on for posible `bait
7: later if I can thin UP
6: some THIN
5: reminds me of
4: Shadow [spokes]
3: in the rings of Saturn
2: thats all I have at
1: "THIS TIME" 1:34 A.M. pst

Comixx
2002-Mar-26, 11:10 AM
As I posted a little while ago, there is another fellow named James McCanney who thinks there's more to comets than the dirty snowballs we currently believe them to be. DStahl kindly provided a link to McCanney's site (http://www.usinternet.com/users/jmccanney/) where you can also find versions of his paper. I'm interested in this line of thought too...but it all seems like an exercise in futility until we get better images and analysis of comet nucleii.

<font size=-1>[ This Message was edited by: Comixx on 2002-03-26 06:15 ]</font>

John Kierein
2002-Mar-26, 12:19 PM
We have some good closeups of a couple of comet nuclei. Halley in particular. Deep Impact will actually penetrate a comet! I have a few friends working on that spacecraft.

Karl
2002-Mar-26, 03:16 PM
I have a number of friends working on the Rosetta program, which is now in it's final testing before launch.

http://spdext.estec.esa.nl/content/doc/e5/2277_.htm

http://www.sci.esa.int/content/news/index.cfm?aid=13&cid=398&oid=29695

Why do I have the feeling that even after a probe is landed on a comet and performs direct measurements that the "Electric Comet" people will call it big cover-up??

The Langmuir Probe on board will be very sensitive to electric fields.

dapted
2002-Mar-26, 04:39 PM
I don't buy the electric comet theory either. My theory has to do with light pillars caused by ice cystals, or some other frozen crystalized gas co-orbiting with the comet and reflecting and refracting light to the observer. This effect allows the near end and the far end of a multi-million mile tail to be the same (approximately) distance from the viewer and thus appear straight. Here are some links.
<a href=http://www.netppl.fi/~jarmom/haloguid/halogal.htm> Halos and Pillars</a>
<a href=http://www.genesismission.org/product/genesis_kids/ropingrainbows/ropingrainbows.html> Simplest explanation of light pillars </a>

<a href=http://www.weather-photography.com/Guest/photos.html> sun pillars and halos</a>

More sun pillar photos (http://www.astrophys-assist.com/wilobs/weathwin/sunpillr.htm)

another good sun pillar (http://antwrp.gsfc.nasa.gov/apod/ap010313.html)


<a href=http://www.meteoros.de/englisch/ee08e.htm> Pillar explanation</a>
Better Pillar explanation (http://www.islandnet.com/~see/weather/eyes/pillars.htm)

One more explanation (http://www.netppl.fi/~jarmom/haloguid/halot.htm)

If there are frozen crystals in co-orbit with comets, and if those crystals can be aligned by balance between solar gravity as accelerator and solar wind as drag then a pillar could be formed. Said pillar explains how a comet tail can look so long and straight when by all orbial math it should be an arc.

Dan

GrapesOfWrath
2002-Mar-26, 05:03 PM
On 2002-03-25 23:42, dapted wrote:
The Ion tail on the comet should look like an arc. Can anybody provide a reasonable explanation?

Sure. In the two examples that you gave, tracer bullets, and water streams, the arcs that you see when you move the gun or hose sideways is in part a result of the fact that you start your sideways movement from a stand still. In other words, you are accelerating the gun or hose to the right or left.

Acceleration produces arcs, as the familiar gravity parabolas attest. If you were to mount a gun on a train and fire the tracers as the train was moving at a constant speed, the path of the tracers would appear to be more like a straight line (except for their fall due to gravity--but I'm sure you mean the sideways motion). That's a result of the combination of the two essentially linear motions.

For the comet, its motion is not strictly constant, but it is close enough for the time that we observe it.

dapted
2002-Mar-26, 08:49 PM
Sorry to disagree with you but the tail starts out almost directly behind the comet as it approaches the sun from way out in space. The tail is short, and it movement can't be detected, then as it nears the sun it accelerates its swing as it goes around the sun. Once the comet has gone most of the way around it starts its outbound trajectory the distant end is now well in advance of the comet and the swing is much slower. Watch a sprinkler on a hayfield. In just a few seconds of travel time it still looks like an arc. If the ion emitting material is moving at 300 to 400 KPH, which is pretty close to 100% of the speed of the solar wind (I doubt it could even come close to that, and the comet tail is 150 million kilometers long and straight as an arrow.

Here is a quote from <a href=http://tweens.indiatimes.com/twt_pg/tweencyclopedia/universe/deepimpact.htm> a sposedly knowledgable source</a>

"The solar wind, which consists of high-speed atomic nuclei, protons, and electrons, sweeps cometary gases away from the Sun, producing a straight tail up to 93 million miles (150 million kilometres) in length. A second tail consisting of dust particles may also appear. This dust tail is shorter and more curved than the gas tail. A comet tail always points away from the Sun because of the force exerted by the solar wind and the Sun's radiation on the cometary material. Therefore, when a comet travels away from the Sun, its tail or tails are always in front of it. Some comets have been observed to develop as many as nine tails."

If you believe this then the material from the comet at 100% of the speed of solar wind will take 20 days to get there. A comets tail will have turned a long way around the sun in 20 days time.

In addition you have to find a way to believe that any ionizing material can be accelerated to that speed in the first place. Thus at best figure 200 days for the material to make it to the end at a still unbelievable speed of 10% of the speed of the solar wind. When they dump water from the space shuttle they have to aim it straight down toward the earth in order to keep it from becoming a problem. If solar wind would carry it away they would not have to do that. Here is a page with an explanation and a photograph of a water dump by the space shuttle
<a href=http://www.eclipsetours.com/sat/shuttle.html> Paul Maley's page about the shuttle activites. </a>

This proves ice crystals can exist in space, and it shows what happens to matter when you jettison it to a different orbit. In this case it is jettisoned to a lower orbit, which has less distance to travel, thus the arc curves ahead of the shuttle. It hasn't really sped up, it just has to travel less distance than the shuttle as it moves around the planet. Also note that the solar wind did not blow it away.

dapted
2002-Mar-26, 08:52 PM
On 2002-03-26 10:16, Karl wrote:
I have a number of friends working on the Rosetta program, which is now in it's final testing before launch.

http://spdext.estec.esa.nl/content/doc/e5/2277_.htm

http://www.sci.esa.int/content/news/index.cfm?aid=13&cid=398&oid=29695

Why do I have the feeling that even after a probe is landed on a comet and performs direct measurements that the "Electric Comet" people will call it big cover-up??

The Langmuir Probe on board will be very sensitive to electric fields.


Thanks I enjoyed reading those pages. I wish they could launch earlier though. I may not make it to 2011.

Dan

Gsquare
2002-Mar-27, 01:29 AM
Dan,
I read with interest your post.
I edited my post when I realized you wanted an answer to why there is no curvature in the ion tail. (apparently you realize the dust tail does show apparent curvature)

First, the origin of the tails are different:
The ion tail originates from the interaction of a highly charged solar WIND ( and associated solar magnetic field) with the charged gas that surrounds the cometary necleus. The result is an emission spectrum from the recombination of charged particles with electrons.

The dust tail on the other hand arises from solar pressure, (i.e. solar E.M. RADIATION)that forces molecules off the surface of the comet. It is observable by reflection.

Now to correct a error. 1st, the solar WIND (that causes the ion tail) travels at a stagering 400 or so Kilometers PER SECOND, not per hour as you gave in your post. This is about a million miles per hour! And is over 100 time as fast as the orbital velocity of, say Comet Hale Bopp at its FASTEST point (at perihelion).

With such a high tail velocity we would not expect the curvature to be perceptible. It would be like (in your garden hose analogy) moving the head of the nossel very slowly with respect to the speed of the water coming out - there would be very little arching.
In an equal amount of time that the comet moved 100 km. the tail would have traveled over 10000 km. A little trig. would show that this is less than 1/2 degree of arc.

For an ion tail to have gone out 4 million miles only takes 4 hours and the comet has only moved 40 k miles. (Again, 1/2 degree curvature). Even the width of the tail would be greater than 40 k miles.
(Also, note that the visible length of the tail is limited by the lifetime of ionic recombination of gas and solar wind.)

I believe that's the solution to your problem.

G^2






<font size=-1>[ This Message was edited by: Gsquare on 2002-03-26 22:56 ]</font>

dapted
2002-Mar-27, 04:10 AM
Thanks for the explanation, but I used 200kps, Kilometers per second. using your 400kps x 60 seconds yeilds 24,000 kilometers per minute x60 yeilds 1,440,000 per hour. So at 100% efficiency assuming no loss of speed due to the comet and its coma being in the way of the solar wind, it would take 100 hours to go 144 million kilometers. The article above quoted the Ion tail as being 150 million kilometers long.

How much angular movement is there in the tail in 4 days? use the perihelium swing for this debate.

I am not good at trig.

<font size=-1>[ This Message was edited by: dapted on 2002-03-26 23:13 ]</font>

2002-Mar-27, 09:37 AM
3:28 A.M.? 20020327
On 2002-03-26 11:39, dapted wrote:

<a href=http://www.netppl.fi/~jarmom/haloguid/halogal.htm> Halos and Pillars</a>
<a href=http://www.genesismission.org/product/genesis_kids/ropingrainbows/ropingrainbows.html> Simplest explanation of light pillars </a>

<a href=http://www.weather-photography.com/Guest/photos.html> sun pillars and halos</a>

More sun pillar photos (http://www.astrophys-assist.com/wilobs/weathwin/sunpillr.htm)

another good sun pillar (http://antwrp.gsfc.nasa.gov/apod/ap010313.html)


<a href=http://www.meteoros.de/englisch/ee08e.htm> Pillar explanation</a>
Better Pillar explanation (http://www.islandnet.com/~see/weather/eyes/pillars.htm)

One more explanation (http://www.netppl.fi/~jarmom/haloguid/halot.htm)

3:29 A.M. Yep

Gsquare
2002-Mar-27, 02:13 PM
..it would take 100 hours to go 144 million kilometers. The article above quoted the Ion tail as being 150 million kilometers long.

How much angular movement is there in the tail in 4 days? use the perihelium swing for this debate.
I am not good at trig.

No matter what time frame you use, the relative speeds (and thus relative distances)stays the same, so the arc is the same.

In any time period the ratio of distance covered by the comet vs. radial distance covered by the tail stays the same, (assuming the period isn't so long that the orbital speed has changed significantly). Thus using tangent, we see that the amount of angular change from the front to the rear of the tail is the same, about 1/2 degree.

The amount of arching is based on the relative speeds (solar wind vs. orbital speed), not the time frame.

The dust tail,however, is blown off at lower speeds by radiation pressure and thus arching is much more apparent.
Hope that's more understandable.

G^2



<font size=-1>[ This Message was edited by: Gsquare on 2002-03-27 10:19 ]</font>

Gsquare
2002-Mar-27, 02:15 PM
<font size=-1>[ This Message was edited by: Gsquare on 2002-03-27 09:16 ]</font>

Ranma
2002-Mar-28, 01:34 AM
Gsquare beat me to it. In a nutshell, the difference between the speed of the solar wind compared to that of the comet is just too great for any ion tail arcing(sp?) to be perceptible. There's also the vantage point to take into account here. Pretty much always, we see the comet sideways from the Earth(usually, we see comets as they're traveling towards the sun (anyway, in my own relatively short(20 years) comet-gazing experience)). An arc, looking at it sideways, looks like a straight line. So even if a comet would have a perceptible arc, we wouldn't see it.

dapted
2002-Mar-28, 04:31 AM
Thanks G I appreciate the effort but I guess I must be daft. Anytime you see a water discharge from the shuttle, they launch it into a lower orbit. When they do this the water appears to arc forward of the shuttle. Orbital mechanics says it should as it now has less distance to circle the globe but it is still moving at the same forward velocity as it had when it was on board the shuttle. If they were to launch it into a higher orbit, away from the earth it should arc backwards relative to the shuttle, again because it now has a longer distance to go to get around the globe, but it is still moving at the speed of a lower orbit.

So then go back to the comet, it is launching material which is, or will be ionizing into a much higher orbit, but the forward velocity has had no energy input to make it move at the faster speed required to orbit the sun in the same period of time as the comet. 150 million killometers is a hugely long ways. Assuming the solar wind is responsible for putting it up that fast, what is the mechanism to make the orbital speed come up?
Dan

Karl
2002-Mar-28, 11:42 AM
On 2002-03-27 23:31, dapted wrote:
Assuming the solar wind is responsible for putting it up that fast, what is the mechanism to make the orbital speed come up?
Dan


When the material is ionized it becomes a plasma, i.e. a mixture of electrons and positively charged nuclei and molecules. These solar wind plasma also consists of charged particles travelling at high speeds (high energies). Because of the electric fields of the particles, they can interact at much further distances than if they were neutral, so collisions between the solar wind plasma and the comet plasma transfer energy to the comet particles and accelerate them to the solar wind velocity. This is called "ion pickup".

http://www.agu.org/pubs/abs/nja/97JA02667/97JA02667.html

GrapesOfWrath
2002-Mar-28, 01:42 PM
The shuttle takes an hour and a half to go around the Earth, comets may take hundreds or thousands of years to go around the Sun. Their angular velocity is a lot less.

dapted
2002-Mar-28, 02:27 PM
Not buying it. You are most probably correct, but I dont see it. Put another way, this Ion tail, if it exists, is the only thing in the Universe that makes a straight line, other than rays which are an illusion caused by sunlight moving through a cloud or other object which is not straight at all. To my eye, and pea sized brain, the only explanation of the Ion tail is that the Ion tail is an effect of light ie photons exciting small amounts of matter which must surround the comet, I just can't make the leap to any matter being instantly accelerated to 400kps. I can imagine the effect moving that fast. Kind of like the Aurora Borealis. The Ionic effect moves at those speeds. But the underlying matter which emits the photons is essentially upper atmosphere and is sitting still, relative to the solar winds which ignite the event.

dapted
2002-Mar-28, 03:27 PM
On 2002-03-28 09:27, dapted wrote:
Not buying it. You are most probably correct, but I dont see it. Put another way, this Ion tail, if it exists, is the only thing in the Universe that makes a straight line, other than rays which are an illusion caused by sunlight moving through a cloud or other object which is not straight at all. To my eye, and pea sized brain, the only explanation of the Ion tail is that the Ion tail is an effect of light ie photons exciting small amounts of matter which must surround the comet, I just can't make the leap to any matter being instantly accelerated to 400kps (without some sort of Fission/Fusion style accelerant). I can imagine the effect moving that fast. Kind of like the Aurora Borealis. The Ionic effect moves at those speeds. But the underlying matter which emits the photons is essentially upper atmosphere and is sitting still, relative to the solar winds which ignite the event.

Karl
2002-Mar-28, 03:32 PM
On 2002-03-28 09:27, dapted wrote:
Not buying it. You are most probably correct, but I dont see it. Put another way, this Ion tail, if it exists,

It was first measured directly by the spacecraft ICE/ISEE-3 on September 11, 1985. (I built part of the instumentation.)

http://www.sp.ph.ic.ac.uk/~balogh/isee3.htm



the only explanation of the Ion tail is that the Ion tail is an effect of light ie photons exciting small amounts of matter which must surround the comet,

Photoionization is in fact a key factor in producing plasma from the comet source material.



I just can't make the leap to any matter being instantly accelerated to 400kps.

It isn't instant.



I can imagine the effect moving that fast. Kind of like the Aurora Borealis. The Ionic effect moves at those speeds. But the underlying matter which emits the photons is essentially upper atmosphere and is sitting still, relative to the solar winds which ignite the event.

The solar wind doesn't directly excite aurora, solar wind particles are trapped in the magnetosphere and acceleration processes occur which dump electrons into the upper atmosphere. These electrons follow magnetic field lines, not straight lines.




<font size=-1>[ This Message was edited by: Karl on 2002-03-28 10:34 ]</font>

Kaptain K
2002-Mar-28, 04:15 PM
...{The} Ion tail, if it exists, is the only thing in the Universe that makes a straight line...
There is a distinct difference between "straight" and "apparently straight". As has been pointed out, the curvature of the ion tail is approximately 1/2 degree. This is the maximum arc that can be observed (and only if the orbit of the comet is such that its path is perpendicular to our line of sight). If the orbit is such that it is moving directly across our line of sight, it will appear to be straight (no matter how curved it "really" is.

_________________
When all is said and done - sit down and shut up!

<font size=-1>[ This Message was edited by: Kaptain K on 2002-03-28 11:17 ]</font>

Gsquare
2002-Mar-28, 05:31 PM
On 2002-03-27 23:31, dapted wrote:
Thanks G I appreciate the effort but... Anytime you see a water discharge from the shuttle..... If they were to launch it into a higher orbit, away from the earth it should arc backwards relative to the shuttle, again because it now has a longer distance to go to get around the globe, but it is still moving at the speed of a lower orbit.


Thanks for the response, dapted, but your shuttle discharge example is not at all analogous to the comet. In fact, it's the inverse.
In the shuttle example the only reason you observe the arching is because the forward velocity is SO MUCH GREATER than the outward (radial) velocity of the water. In a comet its just the opposite. (GOW alluded to this).

TO MAKE the shuttle ANALOGOUS TO THE COMET:
the shuttle would need to slow down to say 10 mph (and still stay in orbit) AND the water would have to be spewed out at over 1000 mph to a higher orbit; then you would see no arching (provided the water dissapted after it gets to that height as does an ion tail). Only then can it be analogous to the comet since the ORBITAL velocity would only be 1/100 th the RADIAL velocity of the water. In a comet it's the orbital velocity that is very low relative to the HIGH radial velocity of the jet of ion material.
Thus, no mechanism is needed to make the orbital speed of the tail increase so as to keep it straight. Essentially, an ion particle from the head reaches the end of the tail so fast (before dissapation) that there is very little ORBITAL distance traveled to make curvature detectable.

G^2

P.S. Note: Even in DUST tails where the curvature IS significant enough to be detected,(as mentioned by Ranma & Kaptain K), the curvature may be hidden by an unfortunate line of sight wrt earth; a factor which will vary depending upon relative inclination of orbits, longitudes, etc.




<font size=-1>[ This Message was edited by: Gsquare on 2002-03-28 13:23 ]</font>

dapted
2002-Mar-29, 03:35 AM
On 2002-03-27 20:34, Ranma wrote:
Gsquare beat me to it. In a nutshell, the difference between the speed of the solar wind compared to that of the comet is just too great for any ion tail arcing(sp?) to be perceptible. There's also the vantage point to take into account here. Pretty much always, we see the comet sideways from the Earth(usually, we see comets as they're traveling towards the sun (anyway, in my own relatively short(20 years) comet-gazing experience)). An arc, looking at it sideways, looks like a straight line. So even if a comet would have a perceptible arc, we wouldn't see it.

Correct I see that point, but I have looked at thousands of photographs of comets and they appear to run the gammut as far as vantage point. Some even seem to have an Ion tail that points both toward the sun and away from it. And none of them show any sort of Arc. Even a 1/4 degree of arc would be perceptable. Plus there is the fact that the Ion tail usually seems to be where a shadow would be if there were one.

dapted
2002-Mar-29, 05:01 AM
I know there is a limit to argument but I haven't reached my limit yet. Assume the comet at its closet approach to the sun is 1 au, approximately 150 million kilometers. Assume it's tail is 1 au as well, another 150 million kilometers. The top of the arc or 1/4 way around the sun give or take a little is a path of approximately 23,500 million kilometers. The path taken by the tip of the tail is closer to 47,000 million miles. Thus to cover the different distances in the same amount of time requires the tip to be moving approximately twice as fast as the base of the tail in Oribtal velocity. Since nothing accelerated the orbital velocity as the material made it's way out to the end of the tail, orbital velocity being perpendicular to the solar wind, the tail should have a significant arc. It should look like a swirl of an arm on a galaxy for crying out loud. Yes it would look straight or nearly so if viewed from the same plane, but deep space 1 was definately in multiple different positions. Still no arc is visible. The arc has nothing to do with the speed differential between the orbital speed of the comet and the time it speed of the matter getting to the end. even if it is instantaneous the arc is evident. You can plot it with a piece of graph paper and make it simultaneous. The matter in the higher orbit has to fall behind. The arc is totaly dependent on the difference in orbital speed between the lower orbit of the comet and the higher orbit of the matter at the tip of the tail. Only if the tip of the tail accelerates to double the orbital speed of the comet can it appear to be a straight line.

Thus my insistance that the matter which is being ionized must be there well before the event which causes it to plasma. An unseen thin cloud of material waiting for the shadow of the coma to eiter begin the plasma event, or perhaps maybe it just takes the shadow for the event to be seen, an ambient lighting kind of thing, or the one I like best a light pillar caused by the soft glow of the coma making it appear as if the ion tail exists when it doesn't. What ever the mechanism, I dont buy matter being accelerated out the tail producing the apparent tail apparition.

I am too old and stubborn to give in. Probably too dumb too! <grin> No need to get mad, I know I am an exasperating fool! I can live with it, hopefully you can too.

GrapesOfWrath
2002-Mar-29, 07:47 AM
On 2002-03-29 00:01, dapted wrote:
You can plot it with a piece of graph paper and make it simultaneous.

And that is exactly what you should do. Find a real photo, and get the actual parameters, and plot the graph. How does it compare to the photo?

Karl
2002-Mar-29, 11:57 AM
On 2002-03-29 00:01, dapted wrote:
. . . or the one I like best a light pillar caused by the soft glow of the coma making it appear as if the ion tail exists when it doesn't.


http://www.solarviews.com/thumb/comet/comet.gif

If the ion tail doesn't exist, what were all of those spacecraft measuring?

Gsquare
2002-Mar-29, 02:00 PM
Am I the only one or has anyone else noticed
... that every time you anwer an objection the objection changes?
I'm beginning to realize this is one of those cases of 'My mind is made up so don't bother me with the facts'.

Nice graphics Karl.
G^2

By the way,Karl, you may be aware of the recent discovery of a third tail, a neutral Sodium tail, in Hale Bopp, which places it in about the same position as the 'hydrogen envelope' in your graph. Not sure of the origin - It reminds me of the moon's sodium 'trail'. Any ideas?


<font size=-1>[ This Message was edited by: Gsquare on 2002-03-29 09:10 ]</font>

Karl
2002-Mar-29, 03:12 PM
On 2002-03-29 09:00, Gsquare wrote:

Nice graphics Karl.
G^2

Haven't yet found the graphic I'm looking for, that shows the actual angle of the solar wind w.r.t. the sun position vector. Due to the garden hose effect the ion tail isn't directly out from the sun.

http://space.rice.edu/IMAGE/livefrom/sunearth.html

Even though the energy flux in the solar wind is far less intense than sunlight, it is important because charged particles respond to the electric and magnetic fields in the solar wind. Consider a comet - Figure 4 shows Comet Hale-Bopp from 1997. The brightest tail of the comet is the dust tail. The yellowish dust tail points away from the Sun because the pressure of sunlight bouncing off its dust particles. It curves slowly because the dust particles have a significant mass. The other comet tail is the ion tail - here the blue tail seen above the dust tail. This tail is caused by ionized particles being pushed away from the sun not by sunlight but by the pressure of the solar wind. The comet's neutral atmosphere, the coma, is ionized by sunlight (the neutral atoms are stripped of one or more electrons by absorbing energetic particles of light, or photons). The coma is also ionized by electron impact - electrons in the solar wind striking the comet's atoms or molecules, knocking off additional electrons in the process and leaving the initial atom or molecule as a positively charged ion. The resulting ions and electrons are "picked up" by the solar wind and join with the flow, which also points away from the Sun but at a slightly different angle. The blue color is caused by sunlight scattering off of OH+ ions.






By the way,Karl, you may be aware of the recent discovery of a third tail, a neutral Sodium tail, in Hale Bopp, which places it in about the same position as the 'hydrogen envelope' in your graph. Not sure of the origin - It reminds me of the moon's sodium 'trail'. Any ideas?


Yeah, I heard about it, but haven't read anything in detail about it. Been up to my eyeballs for the past four months getting an instrument delivered and am just now coming up for air.

Edit to fix characters in quote.

<font size=-1>[ This Message was edited by: Karl on 2002-03-29 10:24 ]</font>

GrapesOfWrath
2002-Mar-29, 03:40 PM
On 2002-03-29 10:12, Karl wrote:
Been up to my eyeballs for the past four months getting an instrument delivered and am just now coming up for air.

About time, welcome back. You may be the most un-newbie newbie we got.

Karl
2002-Mar-29, 04:27 PM
On 2002-03-29 09:00, Gsquare wrote:

By the way,Karl, you may be aware of the recent discovery of a third tail, a neutral Sodium tail, in Hale Bopp, which places it in about the same position as the 'hydrogen envelope' in your graph. Not sure of the origin - It reminds me of the moon's sodium 'trail'. Any ideas?


<font size=-1>[ This Message was edited by: Gsquare on 2002-03-29 09:10 ]</font>


Found this, but have only read the abstract:

http://xxx.lanl.gov/abs/astro-ph/9710022

Karl
2002-Mar-29, 04:50 PM
On 2002-03-29 10:40, GrapesOfWrath wrote:

About time, welcome back. You may be the most un-newbie newbie we got.


Thanks, I'll hopefully maintain quality over quantity. /phpBB/images/smiles/icon_smile.gif

GrapesOfWrath
2002-Mar-30, 03:46 AM
It's possible to have both. /phpBB/images/smiles/icon_smile.gif

dapted
2002-Mar-30, 05:31 AM
On 2002-03-29 06:57, Karl wrote:


On 2002-03-29 00:01, dapted wrote:
. . . or the one I like best a light pillar caused by the soft glow of the coma making it appear as if the ion tail exists when it doesn't.


http://www.solarviews.com/thumb/comet/comet.gif

If the ion tail doesn't exist, what were all of those spacecraft measuring?


Good Question. Love the drawing. Why is dust cloud falling behind? No Drag, Any acceleration of comet by gravity would have same effect on dust. Solar wind would push dust to higher orbit. Newtons 3rd says big and small must accelerate at the same speed, fall the same distance in the same time. Or am I misquoting?

dapted
2002-Mar-30, 05:43 AM
On 2002-03-29 09:00, Gsquare wrote:
Am I the only one or has anyone else noticed
... that every time you anwer an objection the objection changes?
I'm beginning to realize this is one of those cases of 'My mind is made up so don't bother me with the facts'.

Nice graphics Karl.
G^2

By the way,Karl, you may be aware of the recent discovery of a third tail, a neutral Sodium tail, in Hale Bopp, which places it in about the same position as the 'hydrogen envelope' in your graph. Not sure of the origin - It reminds me of the moon's sodium 'trail'. Any ideas?


<font size=-1>[ This Message was edited by: Gsquare on 2002-03-29 09:10 ]</font>


Hello Gsquare. I am a bit on the disorganized side. Sorry for jumping around with the arguement. I cant't put all my arguements out at once, there are so many.

Here is another one. Many photos of comets, and my own observations of Hale Bop showed no tail at all, only a big smudge in the sky. Nothing at all like the drawings and the perfect photos that get all the press. Since Light pillars only happen when the angle of the dangle is just right, you would only get an apparent tail at certain angles. So it seems to be with comets.

What I saw with Hale bob looked more like a fog bank that got more diffuse as it got further away from the brightest part of the comet, which is called the coma.

Do you know of any time hacked photos of the same comet at the same time but from different perspectives. Say from earth and from Deep Space one?

If they both see the same thing, it could prove something, if they saw different things it might indicate something else?

Dan

dapted
2002-Mar-30, 05:46 AM
On 2002-03-29 02:47, GrapesOfWrath wrote:


On 2002-03-29 00:01, dapted wrote:
You can plot it with a piece of graph paper and make it simultaneous.

And that is exactly what you should do. Find a real photo, and get the actual parameters, and plot the graph. How does it compare to the photo?


OK I have my graph paper and I have plotted it. It is easily descernable as an arc. Now what? It doesn't look anything like the drawings.

BTW, how can I put those drawings on this page?

Dan

Karl
2002-Mar-30, 12:11 PM
On 2002-03-30 00:31, dapted wrote:

Good Question.

Do you have an answer?



Love the drawing. Why is dust cloud falling behind? No Drag, Any acceleration of comet by gravity would have same effect on dust. Solar wind would push dust to higher orbit. Newtons 3rd says big and small must accelerate at the same speed, fall the same distance in the same time. Or am I misquoting?


You are assuming that the light pressure applies the same acceleration. This is not correct. Assuming a spherical particle, the cross sectional area that the light fall upon is proportional to r<sup>2</sup>, whereas the mass is proportional to r<sup>3</sup>. Therefore the smaller particles will be have a proportionally larger force acting on them in a radial direction. Since the tangential (orbital) velocity component stays the same, the radial force moves the particle into a higher (longer) orbit and it fall behind the parent body.

Edit to fix HTML.

<font size=-1>[ This Message was edited by: Karl on 2002-03-30 07:12 ]</font>

dapted
2002-Mar-30, 01:30 PM
On 2002-03-30 07:11, Karl wrote:


On 2002-03-30 00:31, dapted wrote:

Good Question.

Do you have an answer?

Only my theory that the underlying matter which Ionizes with the solar wind was not accelerated all that much at all. It is most of the time nearly invisible because it is so diffuse. For what ever reason, perhaps temperature, perhaps ambient lighting, the Ionization occurs in that space which has less photonic activity. Perhaps due to the diffuse cloud having crystals of frozen matter which can cause a light pillar are in the cloud and the Ion tail isn't there at all. Perhaps, perhaps, perhaps. Lots of theories, with lots of flaws.



Love the drawing. Why is dust cloud falling behind? No Drag, Any acceleration of comet by gravity would have same effect on dust. Solar wind would push dust to higher orbit. Newtons 3rd says big and small must accelerate at the same speed, fall the same distance in the same time. Or am I misquoting?


You are assuming that the light pressure applies the same acceleration. This is not correct. Assuming a spherical particle, the cross sectional area that the light fall upon is proportional to r<sup>2</sup>, whereas the mass is proportional to r<sup>3</sup>. Therefore the smaller particles will be have a proportionally larger force acting on them in a radial direction. Since the tangential (orbital) velocity component stays the same, the radial force moves the particle into a higher (longer) orbit and it fall behind the parent body.

Edit to fix HTML.

<font size=-1>[ This Message was edited by: Karl on 2002-03-30 07:12 ]</font>


So the arguement is that the dust tail falls behind because it is moved into a higher (longer) orbit, which makes them fall behind. But the matter which Ionizes, and recombines, and moves to an much higher (longer) orbit not only doesn't fall behind, but moves in front of the comet by the time the comet is exiting close orbit. You can't have it both ways. If it moves to a higher (longer) orbit it has to fall behind. Period.
Another arguement, if solar energy causes the dust tail to move behind the comet, and into the higher orbit why on exiting close orbit, when solar energy is from the rear does the dust tail continue trail behind the comet. Newtons third again. Yet the dust cloud continues to trail like exhaust following a rocket. Solar energy is not causing the dust to trail behind. Something else must be.

Please do not get me wrong. I do not have all the answers, far from it. I have postulations which fit my knowledge and experience, which are different from others. Therefore different things make sense to me. If the dust tail in trail theory works for you, then god bless ya. But from my perspective the tails must behave differently if they are caused by solar energy. Since I don't grasp the physics which would cause these tails to behve so differently from what my physics says they should, I am going to continue to try to find new possibilities. And wait for the Rosetta project to provide some or all of them.

<font size=-1>[ This Message was edited by: dapted on 2002-03-30 08:38 ]</font>

Karl
2002-Mar-30, 02:01 PM
On 2002-03-30 08:30, dapted wrote:

So the arguement is that the dust tail falls behind because it is moved into a higher (longer) orbit, which makes them fall behind. But the matter which Ionizes, and recombines, and moves to an much higher (longer) orbit not only doesn't fall behind, but moves in front of the comet by the time the comet is exiting close orbit.

There are two different regimes operating here. The macroscopic dust particles are acted on primarily by gravitational and light pressure forces. Atomic and molecular level particles are acted on by primarily electromagnetic forces which are orders of magnitude higher than gravity, so gravitational effects are irrelevant. The ion tail flows with the solar wind, that determines the direction rather than orbital mechanics.


You can't have it both ways. If it moves to a higher (longer) orbit it has to fall behind. Period.

No, it doesn't, as has already been explained.

dapted
2002-Mar-30, 03:13 PM
Are you saying that the orbital mechanics of pre or post ionizing matter is affected by some unknown electro-magnetic force which over rides newtons third. The solar pressures may be capable of performing the near instantaneous pick up acceleration to extremely high numbers, and IF you imagine some EMF potential exists, it would either be toward the comet or away from it. It would not push the orbital velocity by hundreds or thousands of percentage points.

Ionizing matter is plasma, but plasma is still matter, not energy. Pre or Post ionization matter is still matter. Unless you have some charged field orbitally ahead of the Ion tail to exert an electro, magnetic, or electro-magnetic pull on the Ionizing material it has to respond to gravity and inertia. Newtons third hasn't been recinded yet.

This is the perfect example of how many otherwise intelligent people are willing to accept comet theory without reasonable explanation. If it has an atomic weight it will have to respond to gravity. It has been demonstrated how solar wind can thoretically counter gravity and accerate ionizing matter into a higher orbit, But nothing demonstrated by the arguments given here, or in any physics book, and I may have read them all, which allows for these phenomenonally huge orbit changes to occur and simultaneously accelerate the orbital speed of the matter.

Face it, the comet theory, as currently modeled and accepted violates Newtons Third. Something has to give.

Gsquare
2002-Mar-30, 03:46 PM
OK I have my graph paper and I have plotted it. It is easily descernable as an arc. Now what? It doesn't look anything like the drawings.
Dan


Not true, Dan.
You're drawing it with the wrong dimensions!

If you want to draw the correct distances that correspond to the comets movements you need to:
1. Draw a straight line 10 mm. (for the comets motion)
2. Then draw a line perpendicular to one end of the first line for 1000 mm. (the tail length).(that's 40 inches!)
Now connect the OPPOSITE end of the 10 mm lime to the end of the 1000 mm tail. (Even if you could accurately draw the correct curvature mechanically; it is only curving 1 mm for every 100 mm length. Without a straight line next to it, curvature is imperceptible.)

This amount of arching is NOT discernable ESPECIALLY when you consider that the tail is not just a thin line;
rather the WIDTH of the 1000mm tail will need to be blurred to a width of about 40 to 70 mm.or more!

You need to take a course in trig. It will become quite obvious to you.

G^2




<font size=-1>[ This Message was edited by: Gsquare on 2002-03-30 12:32 ]</font>

Karl
2002-Mar-30, 04:02 PM
On 2002-03-30 10:13, dapted wrote:
Are you saying that the orbital mechanics of pre or post ionizing matter is affected by some unknown electro-magnetic force which over rides newtons third.

Not unknown at all, the solar wind consists of electrons and (primarily) protons flowing outward at a speed of around 400kps. These particles collide with the ionized comet particles and transfer energy to them, accelerating them to the same velocity and carrying them along. This is known as "pick-up". Gravitational forces are infinitesmal in comparison. Nothing unknown or mysterious about it, been measured and studied for years, experimentally and theoretically. Remember that a charged particle has a much larger effective cross-section than a neutral particle.


The solar pressures may be capable of performing the near instantaneous pick up acceleration to extremely high numbers, and IF you imagine some EMF potential exists, it would either be toward the comet or away from it. It would not push the orbital velocity by hundreds or thousands of percentage points.

Let's say a proton which has just been ionized is traveling with zero velocity relative to the comet nucleus. It now collides with a proton travelling radially outward at 400kps. What happens?


Ionizing matter is plasma, but plasma is still matter, not energy. Pre or Post ionization matter is still matter. Unless you have some charged field orbitally ahead of the Ion tail to exert an electro, magnetic, or electro-magnetic pull on the Ionizing material it has to respond to gravity and inertia. Newtons third hasn't been recinded yet.

No, but the magnitudes and directions of all the applied forces have to be correctly accounted for.


This is the perfect example of how many otherwise intelligent people are willing to accept comet theory without reasonable explanation. If it has an atomic weight it will have to respond to gravity. It has been demonstrated how solar wind can thoretically counter gravity and accerate ionizing matter into a higher orbit, But nothing demonstrated by the arguments given here, or in any physics book, and I may have read them all, which allows for these phenomenonally huge orbit changes to occur and simultaneously accelerate the orbital speed of the matter.

I'd suggest reading "Introduction to Space Physics", by Margaret Kivelson and Chris Russell. From your arguments, I don't think you've read that one.


Face it, the comet theory, as currently modeled and accepted violates Newtons Third. Something has to give.


I would say that the comet theory, as you currently understand it, violates Newtons Third law, but that it actually doesn't.

Kaptain K
2002-Mar-30, 04:39 PM
dapted,

You seem to be making the mistake of thinking that the tail of the comet is always the "same" tail. It is not. The tail is always being replenished from the coma. As the tail diffuses, it quickly reaches the point where it is too thin to be visable. The visable tail is never more than a few days old. The tail visable on the outbound leg is created on the out bound leg, so it points away from the sun.

GrapesOfWrath
2002-Mar-30, 05:11 PM
On 2002-03-30 00:46, dapted wrote:


On 2002-03-29 02:47, GrapesOfWrath wrote:
[quote]
And that is exactly what you should do. Find a real photo, and get the actual parameters, and plot the graph. How does it compare to the photo?


OK I have my graph paper and I have plotted it. It is easily descernable as an arc. Now what? It doesn't look anything like the drawings.

What parameters did you use? Post 'em, and we'll make our own drawings and compare. You can make an html link to your drawings, same as above.

Gsquare
2002-Mar-30, 06:43 PM
On 2002-03-30 11:39, Kaptain K wrote:
dapted,

You seem to be making the mistake of thinking that the tail of the comet is always the "same" tail. It is not. The tail is always being replenished from the coma. As the tail diffuses, it quickly reaches the point where it is too thin to be visable. The visable tail is never more than a few days old. The tail visable on the outbound leg is created on the out bound leg, so it points away from the sun.


Yes, Kaptain K, good point; this needs to be made clear in order for Dan to realize how the relative speeds (comet vs. radial tail speed) determine curvature. He still doesn't seem to get it.

I was going to answer his question on the difference in comet (orbital) speed vs. the orbital speed of the end of the tail; but if he can't understand the simplier (trig.)concept how can he possibly understand orbital mechanics.


In reality, the amount of arching of the ion tail is actually LESS than the 1/2 degree which would be expected from the 100 to 1 ratio of relative speeds (that I posted earlier). (I was never able to get that far since he couldn't get past step 1.)
The reason it is even less is because in determining the distances traveled by the cometary head vs. the radial distance traveled by the tail we made the simple assumption that the tail particles shot straight out radially and had NOorbital velocity. In reality, while the tail particles are moving outward radially from the head, they continue to have a component of motion orbitally (horizontal to the radial) and in the same direction as the comet head, albeit somewhat slower.
This makes the tail particle trajectories arch even less than the 1/2 degree (for Hale Bopp values).

To figure how much less, we use normal Keplerian eqns. which show orb. velocity at the end of the tail decreases by the (1/r)^3/2. Here we have to intergrate over the distance r. Using 1 A.U. for Hale Bopp's perihelion and even if it had a huge tail out to 2 A.U., the orbital velocity only decreases by about 1/2 (if I calc. right). So the ion tail arch must be reduced by another factor of 1/2, making it now only around 1/4 degree of curvature.

G^2


<font size=-1>[ This Message was edited by: Gsquare on 2002-03-30 22:05 ]</font>

dapted
2002-Mar-31, 05:28 AM
Damn, you guys are a tough crowd. I don't think I am going to gain any converts here today. I will try to use a drawing program, paint or something to graph the movement. I will also try to use some median values for recently observed comets. Do you have any favorites?

Mumbling to myself I go away now.

Dan

Karl
2002-Mar-31, 01:01 PM
A model is as good as it's predictions, the current comet model does an excellent job of explaining observations and making predictions about the conditions found near comets.

How does your model improve on what we have?


http://www.mpa-garching.mpg.de/HIGHLIGHT/1999/highlight9910_e.html

GrapesOfWrath
2002-Mar-31, 02:49 PM
On 2002-03-31 00:28, dapted wrote:
I will also try to use some median values for recently observed comets. Do you have any favorites?

Yes, the one you said on 2002-03-30 00:46 that you graphed. What were its parameters? You should have those handy.

dapted
2002-Mar-31, 03:18 PM
I do have them, While I am confident on the speed used for tail velocity, 400kps, the positions for the comet day by day were taken from a website and I had to divide the positon report for 10 to 14 day positions and approximate 1 day increments. Not very scientific of me, but I am not a scientist. I need a velocity number that is representative of a close call and one that is more representative of a 3 or 4 au periheilion arc. I need a number that you guys will agree upon to keep my *** in one piece.

dapted
2002-Mar-31, 03:55 PM
On 2002-03-31 08:01, Karl wrote:
A model is as good as it's predictions, the current comet model does an excellent job of explaining observations and making predictions about the conditions found near comets.

The current model has built in fudge factors to explain why we can't predict the luminoscity of a comet. It doesn't however provide for explanation of why with one comet everybody sees the sudden brightening, while with the next the brightening seems to take a while to make it from one coast to the other (when both coasts are able to see the same comet at the same time). or why sometimes only one position ever sees the brightening at all.

Same thing with tail length. Different lengths at different perspectives at the same time.

How does your model improve on what we have?

I would not agree that my model improves upon it. But it might explain the differences. If a very diffuse cloud exists around the comet, and it is of different densities at different positions it allows for one viewer to be looking through a more or less dense cloud than the next. The light from the coma maintains a more or less stable source of luminescence through my imagined cloud. Solar wind provides an imagined source of drag sufficient to align particles of similar design in their fall toward the sun. Reflection from a flat surface on many particles can explain one type of phenomenon, one position seeing it brighter than the next, or like the perceived dust tail being visible to one viewer, but not to the next. A different type of shape of the molecule depending upon atomic weight could result in perceived different position for a different portion of the spectrum within the cloud. Thus with spectrographic analasys, only one portion of the spectrum could be reflected or refracted from one portion of the cloud. Change the density of the cloud for a person viewing through a different portion of the cloud and you get different emission lines. Now throw in refraction from frozen ice crystals you could easily get a blue portion of the spectrum emitted toward you and your camera. Kind of like the percieved blue emission from a dense ice berg. The ice isn't blue at all, but different portions of the spectrum are absorbed and different ones are reflected or refracted depending on the angle and depending upon the physical shape of the crystal, and upon the elements of which it is constructed. Maybe it isn't ice crystals at all but some other element freezing as it enters the shaded area behind the coma. Clouds in our atmosphere cast a shadow and temperature drops when you enter one. So it could be in the shadow of the coma and the cold of space.

Take all this with a big dose of salt. I am not a scientist, and I don't know the details of many of the phenomenon which I have read about. But I put things I don't understand, but can predict to work for me and my customers every day.

One thing I know is that all the thories have flaws which are not explained away by the known rules. If we knew everything about this phenomenon called comets we would not be sending space craft like the Rosetta project is sending to explore them. Thus there are some high level scientists who agree with me that we need more data.

http://www.mpa-garching.mpg.de/HIGHLIGHT/1999/highlight9910_e.html

dapted
2002-Mar-31, 04:15 PM
On 2002-03-30 11:02, Karl wrote:


On 2002-03-30 10:13, dapted wrote:
Are you saying that the orbital mechanics of pre or post ionizing matter is affected by some unknown electro-magnetic force which over rides newtons third.

Not unknown at all, the solar wind consists of electrons and (primarily) protons flowing outward at a speed of around 400kps. These particles collide with the ionized comet particles and transfer energy to them, accelerating them to the same velocity and carrying them along. This is known as "pick-up". Gravitational forces are infinitesmal in comparison. Nothing unknown or mysterious about it, been measured and studied for years, experimentally and theoretically. Remember that a charged particle has a much larger effective cross-section than a neutral particle.


The solar pressures may be capable of performing the near instantaneous pick up acceleration to extremely high numbers, and IF you imagine some EMF potential exists, it would either be toward the comet or away from it. It would not push the orbital velocity by hundreds or thousands of percentage points.

Let's say a proton which has just been ionized is traveling with zero velocity relative to the comet nucleus. It now collides with a proton travelling radially outward at 400kps. What happens?

In my opinion two things happen, Assuming they don't fuse, or fission, both move in an outward direction depending on angle at which they strike. If it is like a perfectly aligned head on strike, the one stiking moves much more slowly, while the one struck accelerates nearly instantaneously. Like billiard balls struck perfectly. But if it is at an angle, the speed is split between them depending upon the vector of each after the collision. Again use the billiard ball analogy. Since most collisions will be at an angle you get a widely scattered emission of protons moving at widely different angles, With these new angles you get new collisions until an equal proportion are moving in all directions. Is this the answer you wanted? How does this explain lazer like lines of ions behind, and only behind the coma?


Ionizing matter is plasma, but plasma is still matter, not energy. Pre or Post ionization matter is still matter. Unless you have some charged field orbitally ahead of the Ion tail to exert an electro, magnetic, or electro-magnetic pull on the Ionizing material it has to respond to gravity and inertia. Newtons third hasn't been recinded yet.

No, but the magnitudes and directions of all the applied forces have to be correctly accounted for.


This is the perfect example of how many otherwise intelligent people are willing to accept comet theory without reasonable explanation. If it has an atomic weight it will have to respond to gravity. It has been demonstrated how solar wind can thoretically counter gravity and accerate ionizing matter into a higher orbit, But nothing demonstrated by the arguments given here, or in any physics book, and I may have read them all, which allows for these phenomenonally huge orbit changes to occur and simultaneously accelerate the orbital speed of the matter.

I'd suggest reading "Introduction to Space Physics", by Margaret Kivelson and Chris Russell. From your arguments, I don't think you've read that one.

You are right, I have not read that one. But I have read one, a paperback I believe by the same titile but by Atmo Kivelson. I don't remember there being a co-author. Would this be the same one?


Face it, the comet theory, as currently modeled and accepted violates Newtons Third. Something has to give.


I would say that the comet theory, as you currently understand it, violates Newtons Third law, but that it actually doesn't.


Agreed.

Karl
2002-Apr-01, 12:24 AM
On 2002-03-31 11:15, dapted wrote:

Let's say a proton which has just been ionized is traveling with zero velocity relative to the comet nucleus. It now collides with a proton travelling radially outward at 400kps. What happens?

In my opinion two things happen, Assuming they don't fuse, or fission, both move in an outward direction depending on angle at which they strike. If it is like a perfectly aligned head on strike, the one stiking moves much more slowly, while the one struck accelerates nearly instantaneously.

So you would accept this as a nearly instantaneous acceleration mechanism that you had trouble contemplating earlier? The velocities are nowhere close to enough for fusion.


Like billiard balls struck perfectly. But if it is at an angle, the speed is split between them depending upon the vector of each after the collision. Again use the billiard ball analogy. Since most collisions will be at an angle you get a widely scattered emission of protons moving at widely different angles, With these new angles you get new collisions until an equal proportion are moving in all directions. Is this the answer you wanted?

Think about the source of the ions for the new collisions, they will be coming in with the same 400kps outward radial velocity. Particles that scatter in the direction of the flow will be less likely to have collisions, so the ions will be tend to be picked up and flow with the solar wind, not scatter in equal proportions in all directions.


How does this explain lazer like lines of ions behind, and only behind the coma?

When you say behind, would that be on a perfect comet-sun line, or in the direction of the solar wind flow?

http://space.rice.edu/IMAGE/livefrom/4_haleboppbotkinthumb.jpg
Full size image:
http://space.rice.edu/IMAGE/livefrom/4_haleboppbotkin.jpg

Edit: Add image

<font size=-1>[ This Message was edited by: Karl on 2002-03-31 19:47 ]</font>

dapted
2002-Apr-01, 03:19 AM
On 2002-03-31 19:24, Karl wrote:


On 2002-03-31 11:15, dapted wrote:

Let's say a proton which has just been ionized is traveling with zero velocity relative to the comet nucleus. It now collides with a proton travelling radially outward at 400kps. What happens?

In my opinion two things happen, Assuming they don't fuse, or fission, both move in an outward direction depending on angle at which they strike. If it is like a perfectly aligned head on strike, the one stiking moves much more slowly, while the one struck accelerates nearly instantaneously.

So you would accept this as a nearly instantaneous acceleration mechanism that you had trouble contemplating earlier? The velocities are nowhere close to enough for fusion. Yes, I see your point. My problem with it had to do with it being acclerated without a corresponding oposite direction reaction. In this case the proton is not accelerated but mearly swaped with one coming in from the sun. Since we are talking about far fewer coming out the far end than went in the near (sun) end, wouldn't this be seen as reducing the "solar wind" if not in speed, then at least in particle density? And then why would the electron care which proton it chose to connect up with? Whether coming from the sun or one being dislodged from the coma? A proton without an electron is a proton without an electron. And why wait minutes, hours or days to recombine and plasma downstream from the comet?


Like billiard balls struck perfectly. But if it is at an angle, the speed is split between them depending upon the vector of each after the collision. Again use the billiard ball analogy. Since most collisions will be at an angle you get a widely scattered emission of protons moving at widely different angles, With these new angles you get new collisions until an equal proportion are moving in all directions. Is this the answer you wanted?

Think about the source of the ions for the new collisions, they will be coming in with the same 400kps outward radial velocity. Particles that scatter in the direction of the flow will be less likely to have collisions, so the ions will be tend to be picked up and flow with the solar wind, not scatter in equal proportions in all directions. Again, over my head. The electrons are negatively charged, the proton, or neutron/proton combination being struck would have just as good a chance of striking another on the way out as any passing thru that made it to that point would have. If the electron is close enough to be picked up by the ion, isn't it close enough to recombine on the spot?


How does this explain lazer like lines of ions behind, and only behind the coma?

When you say behind, would that be on a perfect comet-sun line, or in the direction of the solar wind flow? I mean in the shadow of the coma of the comet. Which usually means downstream from the Solar Wind. Solar Wind is also applied to currents within the corona of the sun, makes it somewhat confusing since they are not outward bound from the sun except during CME.


http://space.rice.edu/IMAGE/livefrom/4_haleboppbotkinthumb.jpg
Full size image:
http://space.rice.edu/IMAGE/livefrom/4_haleboppbotkin.jpg

Edit: Add image

<font size=-1>[ This Message was edited by: Karl on 2002-03-31 19:47 ]</font>

Karl
2002-Apr-01, 12:15 PM
On 2002-03-31 11:15, dapted wrote:

How does this explain lazer like lines of ions behind, and only behind the coma?


http://centres.xtec.es/recursos/astronom/hb/hb4/hb48/yen74.jpg

Like this?

The strange kinking and acceleration behavior of comet ion tails was evidence that led to the prediction of the existance of the solar wind back in the '40s.

GrapesOfWrath
2002-Apr-01, 12:28 PM
Are the arcs in Karl's image what you are talking about dapted? Or is it more extreme than that?

dapted
2002-Apr-01, 03:09 PM
The arc is the same direction as the dust tail in my crude etch, but similar in form to the arc on the left side of the picture.

That's a great picture by the way.

It also presents the question, why two pictures with only the change of one coast to the other, which in space terms is nearly the same perspective, can show wildly different tails at times? Other times it is nearly exactly the same. So why?

I am not trying to be obstinant, you are good at this, and I want your input. I am not being adversarial. Keep smiling!

Karl
2002-Apr-01, 04:07 PM
On 2002-04-01 10:09, dapted wrote:

It also presents the question, why two pictures with only the change of one coast to the other, which in space terms is nearly the same perspective, can show wildly different tails at times?


Do you have an example of this?

Karl
2002-Apr-01, 05:20 PM
On 2002-03-31 22:19, dapted wrote:


Think about the source of the ions for the new collisions, they will be coming in with the same 400kps outward radial velocity. Particles that scatter in the direction of the flow will be less likely to have collisions, so the ions will be tend to be picked up and flow with the solar wind, not scatter in equal proportions in all directions.

Again, over my head. The electrons are negatively charged, the proton, or neutron/proton combination being struck would have just as good a chance of striking another on the way out as any passing thru that made it to that point would have. If the electron is close enough to be picked up by the ion, isn't it close enough to recombine on the spot?

At these energies, the recombination rate will be low, the electrons and positive ions will have too much energy to hold together, so it will act as another collision.

Think of it as being on the Santa Monica freeway at rush hour on a good day, 70mph bumper to bumper. Now, consider your probability of collision for three cases, going with traffic at 70mph, with traffic at 35mph, or against traffic (any speed /phpBB/images/smiles/icon_smile.gif.

The additional mass dragged along will slow down the total flow rate.

dapted
2002-Apr-02, 03:21 AM
On 2002-04-01 11:07, Karl wrote:


On 2002-04-01 10:09, dapted wrote:

It also presents the question, why two pictures with only the change of one coast to the other, which in space terms is nearly the same perspective, can show wildly different tails at times?


Do you have an example of this?


Sure, there are plenty of examples but Hale Bopp is a really good well photographed example. Look at the March 9th Images as taken from two different positions on the same night, and only a few hundred miles apart. The Ion Tail is on different sides, and is not nearly so far away from the dust tail in one mans photos as it is in the other mans.

<a href=http://www.jpl.nasa.gov/comet/rob3.html> Nasa Photo in Oakley California 3/9/1997</a>

<a href=http://www.comet-track.com/hb/hb.html> Bob Yen's Photo from Mohave Desert on the same evening 3/9/1997 </a>

There are lots of examples of this.

dapted
2002-Apr-02, 03:27 AM
On 2002-04-01 12:20, Karl wrote:


On 2002-03-31 22:19, dapted wrote:


Think about the source of the ions for the new collisions, they will be coming in with the same 400kps outward radial velocity. Particles that scatter in the direction of the flow will be less likely to have collisions, so the ions will be tend to be picked up and flow with the solar wind, not scatter in equal proportions in all directions.

Again, over my head. The electrons are negatively charged, the proton, or neutron/proton combination being struck would have just as good a chance of striking another on the way out as any passing thru that made it to that point would have. If the electron is close enough to be picked up by the ion, isn't it close enough to recombine on the spot?

At these energies, the recombination rate will be low, the electrons and positive ions will have too much energy to hold together, so it will act as another collision.

Think of it as being on the Santa Monica freeway at rush hour on a good day, 70mph bumper to bumper. Now, consider your probability of collision for three cases, going with traffic at 70mph, with traffic at 35mph, or against traffic (any speed /phpBB/images/smiles/icon_smile.gif.

The additional mass dragged along will slow down the total flow rate.


OK but why don't the Ions which scatter to the left, right, or between the sun and the comet exhibit the same recombination with the electrons as those away from the solar wind?, and why would the ION tail swap from one side of the comet, relative to the dust tail, to the other side, with only a few hundred miles perspective change, on the same night? See links in last post.

Dan

Karl
2002-Apr-02, 03:45 AM
On 2002-04-01 22:27, dapted wrote:

OK but why don't the Ions which scatter to the left, right, or between the sun and the comet exhibit the same recombination with the electrons as those away from the solar wind?,


For the same reason that if you pour a bucket of ping-pong balls in a river they will more likely float downstream than upstream.


and why would the ION tail swap from one side of the comet, relative to the dust tail, to the other side, with only a few hundred miles perspective change, on the same night? See links in last post.

Dan


Well, my first impression is that the first image was printed backwards. You see this in astronomical photos all the time.

dapted
2002-Apr-02, 05:56 AM
I saw that too, but it still doesn't explain angle difference between two tails, tail width difference, and tail length differences.

GrapesOfWrath
2002-Apr-02, 10:22 AM
On 2002-04-01 22:45, Karl wrote:
Well, my first impression is that the first image was printed backwards. You see this in astronomical photos all the time.

Yep, here is a Bob Yen 3/9/97 photo from that site (http://www.comet-track.com/hb/HB309_105w.jpg) and here is that Jay Robertson photo (http://www.jpl.nasa.gov/comet/rob3.html) (I don't think it was actually a NASA photo though). You can see that the bright star just off to the side has shifted from right to left.

Karl
2002-Apr-02, 11:11 AM
On 2002-04-02 00:56, dapted wrote:
I saw that too, but it still doesn't explain angle difference between two tails,

How did you measure it?


tail width difference, and tail length differences.


Different lens, magnification, exposure, film, framing.

dapted
2002-Apr-03, 06:16 AM
Last post didn't go, lets try again. I verified angle between tails using aircraft flight planing protractor. Used both edges of each tail, and estimated center of each tail. Does camera type, film type and exposure length cause the angle to change? That doesn't seem likely.

Dan

GrapesOfWrath
2002-Apr-03, 06:32 AM
On 2002-04-03 01:16, dapted wrote:
Last post didn't go, lets try again. I verified angle between tails using aircraft flight planing protractor. Used both edges of each tail, and estimated center of each tail. Does camera type, film type and exposure length cause the angle to change? That doesn't seem likely.

If your exposure (or film or camera) changes, more of the comet might be visible in the photograph--that could widen each tail and close the gap between them.

Which images did you compare? I had to dig a little to find the right date at that one site. How did you measure them--I mean, how did you measure the angle between the tails? Did you use a centerline, or measure the gap between?

Karl
2002-Apr-03, 11:44 AM
On 2002-04-03 01:16, dapted wrote:
Last post didn't go, lets try again. I verified angle between tails using aircraft flight planing protractor. Used both edges of each tail, and estimated center of each tail.

So, you are assuming that the tails are symmetric and have straight edges?


Does camera type, film type and exposure length cause the angle to change? That doesn't seem likely.

Dan


It can and will change the amount of tail visible in the image. If the tail shape is caused by an asymmetric process, the 'center' found between the two 'edges' will change angle.

So you agree it could cause a "tail width difference, and tail length difference"?

dapted
2002-Apr-04, 03:56 AM
If your exposure (or film or camera) changes, more of the comet might be visible in the photograph--that could widen each tail and close the gap between them.

Which images did you compare? I had to dig a little to find the right date at that one site. How did you measure them--I mean, how did you measure the angle between the tails? Did you use a centerline, or measure the gap between?

[/quote]

For purposes of this discussion I used the ones from the two posted sites and March 9th only.
I tried several methods. Gap between, which might be flawed because of obvious width of tail differences. Left edge of Ion tail to Left edge of Dust tail, and imaginary center of Ion tail to imaginary center of dust tail. In many cases the angles were the same or approximately so. But way too many have big differences. The most interesting from my perspective is that More northern latitudes had very similar angles, more southerly latitudes had more clear images and the angles were different than the northerly pictures. The more southerly the latitudes had similar angles with other southerly latitudes. There were exceptions to this pattern, but mostly it seemed to hold true.

I also find that most of the pictures showing a tail were on comets with an inbound trajectory. As the comets pass the turnaround point, the quality pictures seem to diminish in numbers rather dramatically.

When I did this same experiment on photos of past comets, the pattern seems to continue.

This is another indicator to my wee small brain, that there is enough of a possibility that we are looking at a mirage, that it should be considered.

dapted
2002-Apr-04, 04:05 AM
On 2002-04-03 06:44, Karl wrote:


On 2002-04-03 01:16, dapted wrote:
Last post didn't go, lets try again. I verified angle between tails using aircraft flight planing protractor. Used both edges of each tail, and estimated center of each tail.

So, you are assuming that the tails are symmetric and have straight edges?

No not at all, that is not what I assume, or even hint at, But I think if comets are as described by currently accepted theory, on a given night at a given time, every camera should see approximately the same thing. For one to see a foggy smudge, and the next to see no fogginess at all, but a crisp clear comet with a long tail seems unreasonable. Assuming they both have equivalent cameras, skill and viewpoint.


Does camera type, film type and exposure length cause the angle to change? That doesn't seem likely.

Dan


It can and will change the amount of tail visible in the image. If the tail shape is caused by an asymmetric process, the 'center' found between the two 'edges' will change angle.

So you agree it could cause a "tail width difference, and tail length difference"?



Width and length differences seem plausible, Angle between the tails does not. I can't help myself, the whole thing seems more like lots of people photographing a salboat race, but they are looking out over an Arizona desert. The race is real enough, but it is in Santa Monica. The race they are viewing is a mirage.

Mirages are caused by sunlight and atmospherics. Comets are a very thin atmosphere to be sure, But they have enough distance and sunlight to cause a number of possible effects. Seems like something worth looking into.

GrapesOfWrath
2002-Apr-04, 10:20 AM
On 2002-04-03 22:56, dapted wrote:
For purposes of this discussion I used the ones from the two posted sites and March 9th only.

I think that there is more than one at the second site, right?


In many cases the angles were the same or approximately so. But way too many have big differences.

You run into trouble when you measure the gap. Exposure time changes the size. Just look at a Messier object in an a small telescope with your eye, and compare it to the time exposure photographs from larger telescopes--big difference.

Karl
2002-Apr-04, 10:40 AM
On 2002-04-03 23:05, dapted wrote:
[quote]

No not at all, that is not what I assume, or even hint at, But I think if comets are as described by currently accepted theory, on a given night at a given time, every camera should see approximately the same thing. For one to see a foggy smudge, and the next to see no fogginess at all, but a crisp clear comet with a long tail seems unreasonable. Assuming they both have equivalent cameras, skill and viewpoint.

Well, that is a rather huge assumption which I don't holds in many cases. And even in the case of identical equipment, a change in the viewing conditions from one site to the next caused by the air being warmer and/or more humid could prevent one observer from being able to photograph fine detail that another would be able to with identical settings.



Width and length differences seem plausible, Angle between the tails does not. I can't help myself, the whole thing seems more like lots of people photographing a salboat race, but they are looking out over an Arizona desert. The race is real enough, but it is in Santa Monica. The race they are viewing is a mirage.

Mirages are caused by sunlight and atmospherics. Comets are a very thin atmosphere to be sure, But they have enough distance and sunlight to cause a number of possible effects. Seems like something worth looking into.


I read with interest your response to GOW, could you post your measurements and indicate which images they were made from?

Edit to fix spelling error.

<font size=-1>[ This Message was edited by: Karl on 2002-04-04 05:42 ]</font>

dapted
2002-Apr-05, 04:04 AM
On 2002-04-04 05:20, GrapesOfWrath wrote:


On 2002-04-03 22:56, dapted wrote:
For purposes of this discussion I used the ones from the two posted sites and March 9th only.

I think that there is more than one at the second site, right?

Several from the 2nd show up also on the 1st and I probably didn't need to include it at all.


In many cases the angles were the same or approximately so. But way too many have big differences.

You run into trouble when you measure the gap. Exposure time changes the size. Just look at a Messier object in an a small telescope with your eye, and compare it to the time exposure photographs from larger telescopes--big difference.


Yes I see it all the time. That is what picked my curiosity. Stuff I looked at with my telescope, which is supposedly superior to ones used to take great pictures, were very similar to other northern latitudes. Pretty crappy. But other times, I got really outstanding views which I considered better than the pros in the desert and in Australia did. But almost never do my good views co-incide with good shots from colorado or Arizona.

I'd like to compare space born shots of the same comet at the same time from different perspectives. That would eliminate atmospheric differences. Almost impossible to find them though.

dapted
2002-Apr-05, 04:48 AM
On 2002-04-04 05:40, Karl wrote:


On 2002-04-03 23:05, dapted wrote:
[quote]

No not at all, that is not what I assume, or even hint at, But I think if comets are as described by currently accepted theory, on a given night at a given time, every camera should see approximately the same thing. For one to see a foggy smudge, and the next to see no fogginess at all, but a crisp clear comet with a long tail seems unreasonable. Assuming they both have equivalent cameras, skill and viewpoint.

Well, that is a rather huge assumption which I don't holds in many cases. And even in the case of identical equipment, a change in the viewing conditions from one site to the next caused by the air being warmer and/or more humid could prevent one observer from being able to photograph fine detail that another would be able to with identical settings.



Width and length differences seem plausible, Angle between the tails does not. I can't help myself, the whole thing seems more like lots of people photographing a salboat race, but they are looking out over an Arizona desert. The race is real enough, but it is in Santa Monica. The race they are viewing is a mirage.

Mirages are caused by sunlight and atmospherics. Comets are a very thin atmosphere to be sure, But they have enough distance and sunlight to cause a number of possible effects. Seems like something worth looking into.


I read with interest your response to GOW, could you post your measurements and indicate which images they were made from?

Edit to fix spelling error.

<font size=-1>[ This Message was edited by: Karl on 2002-04-04 05:42 ]</font>


OK

<a href=http://www.jpl.nasa.gov/comet/images97041.html> Use this page.</a>

Please check images by Jerry Lodriguss, In New Buffalo PA. Two different shots, different cameras, etc. In both images the left edge of Ion tail to Left edge of Dust tail is 35 degrees.

Right edge to right edge is also 35 degrees.

Center to Center is 30 degrees.

Now scan to same date images by Gregory Terrance in Lima NY.
Left to Left is 25 degrees, Right to Right is 35 degrees and center to center is 22 degrees. It is the same in the last two images even though they are totally different cameras. Ignore the reflector shot which doesn't show any tails at all but a supposed picture of outgassing.

These differences are found over and over again in other pictures.

Here is a good sized gallery of pictures. I chose the ones above because they each had images from different cameras and exposures which yielded virtually identical measurements, but change the perspective and two different cameras yielded identical results to each other, but totally different ones from the other guys. The big difference seems to be geography. And not a big change in that!

Here is a good gallery for you to find your own examples if you would like.

<a href=http://www.jpl.nasa.gov/comet/images.html> Gallery of Comet Photos</a>


http://www.jpl.nasa.gov/comet/images.html

Dan


Edited to post a P.S.

Bob Yen Photo from Mohave Ca. same date yielded very similar results to Lima New York photos L-L 25 degrees, C-C 22 degrees, R-R 35 degrees

Any thoughts?


Dan


<font size=-1>[ This Message was edited by: dapted on 2002-04-04 23:59 ]</font>

Karl
2002-Apr-05, 11:06 AM
On 2002-04-04 23:48, dapted wrote:

Bob Yen Photo from Mohave Ca. same date yielded very similar results to Lima New York photos L-L 25 degrees, C-C 22 degrees, R-R 35 degrees

Any thoughts?


Dan



Dan, I think the differences you are measuring are due the combination of aperture, magnification, and viewing conditions. To make your measurements more repeatable, try scaling the photos so that you are sure you are measuring the same apparent length of tail each time. Also try comparing groups of like apertures.

I think that when you start normalizing your input data set, you will get more consistant outputs.

Firefox
2002-Apr-05, 12:22 PM
Would it also be prudent to keep background stars in mind when scaling the images, and for better comparison?

Karl
2002-Apr-05, 12:52 PM
On 2002-04-05 07:22, Firefox wrote:
Would it also be prudent to keep background stars in mind when scaling the images, and for better comparison?


That would probably be the easiest way to do that. Trying to measure the 'edge to edge' angle of comet tails is a problem of threshold detection. When the boundary is diffuse and fades into the background, you need to set some criteria for declaring that the signal is detectable over the noise. The noise level will change from location to location, and from detector to detector, causing the detectable edge to apparently move.

Edit to clarify last sentence.

<font size=-1>[ This Message was edited by: Karl on 2002-04-05 07:54 ]</font>

dapted
2002-Apr-05, 03:48 PM
On 2002-04-05 07:52, Karl wrote:


On 2002-04-05 07:22, Firefox wrote:
Would it also be prudent to keep background stars in mind when scaling the images, and for better comparison?


That would probably be the easiest way to do that. Trying to measure the 'edge to edge' angle of comet tails is a problem of threshold detection. When the boundary is diffuse and fades into the background, you need to set some criteria for declaring that the signal is detectable over the noise. The noise level will change from location to location, and from detector to detector, causing the detectable edge to apparently move.

Edit to clarify last sentence.

<font size=-1>[ This Message was edited by: Karl on 2002-04-05 07:54 ]</font>


OK, I'll look for examples with similar aperature etc. I wish I could find space mounted cameras shooting from different perspectives.

In my last post I added on some Bob Yen shots. The tail length and width is approximately the same as the Pennsylvania shots, but the angles are more consistent with the New York pictures.

I'll go looking for more "evidence" after work tonight. I am probably wrong in my postulations, but I learn more when I am wrong than when I am right. <grin>

Dan

Karl
2002-Apr-05, 04:15 PM
On 2002-04-05 10:48, dapted wrote:

I'll go looking for more "evidence" after work tonight. I am probably wrong in my postulations, but I learn more when I am wrong than when I am right. <grin>

Dan



Don't we all, I commend you for your efforts.

Karl
2002-Apr-07, 01:28 AM
On 2002-04-05 10:48, dapted wrote:

OK, I'll look for examples with similar aperature etc. I wish I could find space mounted cameras shooting from different perspectives.



http://oposite.stsci.edu/pubinfo/pr/97/08.html

http://www-istp.gsfc.nasa.gov/istp/halebopp/incoming/press/news.html

http://www-istp.gsfc.nasa.gov/istp/halebopp/incoming/press/visna0001.gif

Modified links

<font size=-1>[ This Message was edited by: Karl on 2002-04-06 20:45 ]</font>

dapted
2002-Apr-08, 03:35 AM
Thanks for those links, I had seen the colorfull one before. Again they don't look very similar, but obviously different filters cameras etc.

The second one with the firey looking tail again brings up the orbital dynamics of why this tail doesn't curve more. The sodium is electrically neutral. Solar wind is blowing the wrong direction. I would expect a definate arc. What am I missing?

Dan

Karl
2002-Apr-08, 04:01 AM
On 2002-04-07 23:35, dapted wrote:

The second one with the firey looking tail again brings up the orbital dynamics of why this tail doesn't curve more. The sodium is electrically neutral. Solar wind is blowing the wrong direction. I would expect a definate arc. What am I missing?

Dan



What do you mean when you say the solar wind is blowing in the "wrong" direction?

How much of an arc do you expect, versus what you see?

dapted
2002-Apr-08, 04:27 AM
On 2002-04-08 00:01, Karl wrote:


On 2002-04-07 23:35, dapted wrote:

The second one with the firey looking tail again brings up the orbital dynamics of why this tail doesn't curve more. The sodium is electrically neutral. Solar wind is blowing the wrong direction. I would expect a definate arc. What am I missing?

Dan



What do you mean when you say the solar wind is blowing in the "wrong" direction?


How much of an arc do you expect, versus what you see?


The direction to the sun is not in-line with the direction of the tail, Therefore this tail must be "blown" with a much slower pace than the solar wind. Meaning it would take many days, weeks or months for the sodium to travel that distance from the comet. Just due to the comets travel there should be an arc, but when you factor in how much longer the orbit is for those ions at the end of the tail, the tail should be very exagerated. Then there is the odd specks which are actually well ahead of the aparant path of the comet, and in a higher (longer) orbit. Thus for them to be there, they had to get there via the speed imparted to them by the outgassing process. This means at least hundreds of years of travel time from the comet. If some are sent in this fashion, why not all of them?

If solar wind is responsible, wouldn't the tail be more reminiscent of the Ion tail? At least in this picture, the sodium tail appears to be somewhat between the ion tail and the dust tail. Be interesting to see what this tail is supposed to do as the Ion tail begins to pull way ahead of the dust tail. <grin>

Karl
2002-Apr-08, 04:57 AM
On 2002-04-08 00:27, dapted wrote:


The direction to the sun is not in-line with the direction of the tail, Therefore this tail must be "blown" with a much slower pace than the solar wind. Meaning it would take many days, weeks or months for the sodium to travel that distance from the comet.

Do the math, the scale of the image is 20 million km, the solar wind speed is ~400km/s. So, the age of the Sodium atoms at the end of the tail image is ~16 hours, assuming they have been picked up and accelerated by the solar wind. The acceleration will occur primarily while the atoms are ionized, which increases their likelihood of a collision with a solar wind ion.


Just due to the comets travel there should be an arc, but when you factor in how much longer the orbit is for those ions at the end of the tail, the tail should be very exagerated.

By how much?


Then there is the odd specks which are actually well ahead of the aparant path of the comet, and in a higher (longer) orbit. Thus for them to be there, they had to get there via the speed imparted to them by the outgassing process. This means at least hundreds of years of travel time from the comet. If some are sent in this fashion, why not all of them?

I'm guessing a lot of the odd specks are a combination of stars and detector noise.


If solar wind is responsible, wouldn't the tail be more reminiscent of the Ion tail? At least in this picture, the sodium tail appears to be somewhat between the ion tail and the dust tail. Be interesting to see what this tail is supposed to do as the Ion tail begins to pull way ahead of the dust tail. <grin>


I haven't read the papers, even the ones I've linked to. /phpBB/images/smiles/icon_frown.gif

I'd suppose, that the sodium ions have a faster recombination rate becasue of their higher charge, and since they have a higher mass, end up with a lower average velocity than the hydrogen ions, so the neutral sodium tail lags the 'ion' tail.

Fix tags.

<font size=-1>[ This Message was edited by: Karl on 2002-04-08 00:59 ]</font>

<font size=-1>[ This Message was edited by: Karl on 2002-04-08 01:01 ]</font>

dapted
2002-Apr-08, 06:35 AM
On 2002-04-08 00:57, Karl wrote:


On 2002-04-08 00:27, dapted wrote:


The direction to the sun is not in-line with the direction of the tail, Therefore this tail must be "blown" with a much slower pace than the solar wind. Meaning it would take many days, weeks or months for the sodium to travel that distance from the comet.

Do the math, the scale of the image is 20 million km, the solar wind speed is ~400km/s. So, the age of the Sodium atoms at the end of the tail image is ~16 hours, assuming they have been picked up and accelerated by the solar wind. The acceleration will occur primarily while the atoms are ionized, which increases their likelihood of a collision with a solar wind ion.

If they had been picked up with the solar wind, they would be superimposed with the Ion tail. (at least in the admittedly dimly lit cavity just behind my eyes). Since they are well to the side, the right side in most photos and diagrams, as usually the path of the comet seems to be away from the dust tail.


Just due to the comets travel there should be an arc, but when you factor in how much longer the orbit is for those ions at the end of the tail, the tail should be very exagerated.

By how much?

OK, here is my real shortcomming because I don't remember much from high school trig which was ~35 years ago. But using the circumference of a circle as D X 3.14 the Ions at the end of the tail must travel at least 40 million km times 3.14 so call it 125 million kilometers more than the comet which fosterd them. And since their path is for the most part a vector of the solar wind, they must be traveling much slower.


Then there is the odd specks which are actually well ahead of the aparant path of the comet, and in a higher (longer) orbit. Thus for them to be there, they had to get there via the speed imparted to them by the outgassing process. This means at least hundreds of years of travel time from the comet. If some are sent in this fashion, why not all of them?

I'm guessing a lot of the odd specks are a combination of stars and detector noise. Possible, but certainly not a known quantity. And if they are stars, how much of the rest of the sodium tail is actually something else, other than sodium Ions? I know you can't answer that any better than I can.


If solar wind is responsible, wouldn't the tail be more reminiscent of the Ion tail? At least in this picture, the sodium tail appears to be somewhat between the ion tail and the dust tail. Be interesting to see what this tail is supposed to do as the Ion tail begins to pull way ahead of the dust tail. <grin>


I haven't read the papers, even the ones I've linked to. /phpBB/images/smiles/icon_frown.gif

I'd suppose, that the sodium ions have a faster recombination rate becasue of their higher charge, and since they have a higher mass, end up with a lower average velocity than the hydrogen ions, so the neutral sodium tail lags the 'ion' tail.

I guess I need more education, since the sodium Ions are neutral in charge, why do you say they have a higher charge?

Fix tags.

<font size=-1>[ This Message was edited by: Karl on 2002-04-08 00:59 ]</font>

<font size=-1>[ This Message was edited by: Karl on 2002-04-08 01:01 ]</font>

Karl
2002-Apr-08, 12:48 PM
On 2002-04-08 02:35, dapted wrote:


The direction to the sun is not in-line with the direction of the tail, Therefore this tail must be "blown" with a much slower pace than the solar wind. Meaning it would take many days, weeks or months for the sodium to travel that distance from the comet.

OK, you made me do it, I skimmed through the Sodium tail paper.

They say it is caused by light pressure on the Sodium atoms from "resonance flourescence". They can measure the velocity from the redshift, it increases to about 200km/s at a distance of 60 million km from the nucleus.

http://xxx.lanl.gov/PS_cache/astro-ph/pdf/9710/9710022.pdf

dapted
2002-Apr-09, 06:11 AM
On 2002-04-08 08:48, Karl wrote:


On 2002-04-08 02:35, dapted wrote:


The direction to the sun is not in-line with the direction of the tail, Therefore this tail must be "blown" with a much slower pace than the solar wind. Meaning it would take many days, weeks or months for the sodium to travel that distance from the comet.

OK, you made me do it, I skimmed through the Sodium tail paper.

They say it is caused by light pressure on the Sodium atoms from "resonance flourescence". They can measure the velocity from the redshift, it increases to about 200km/s at a distance of 60 million km from the nucleus.

http://xxx.lanl.gov/PS_cache/astro-ph/pdf/9710/9710022.pdf




Ok, I did a lot more than skim it. The most intelligent thing I can say is ... huh?

My stupidity shines with a brilliance nearly nuclear.

But I did come up with another inane arguement. Put all the tails on a drawing of a comet and you have the Ion tail, the sodium tail, the hydrogen tail, and the dust tail. They are essentially, if I am getting this right, sifted components from the comet. The solar wind had sifted them like a screen sifts different sizes of gravel. Larger their area in relation to their mass, the closer they come to being "blown" straight behind the comet by the solar wind.

At some point in the comets orbit, it unfolds these tails like a japaneese fan. In order for all these things to happen you have to understand vastly complex explanations.

For me and my bumbling, a simpler explanation would have to do with different shapes being likely on different types of dust particles. I can understand solar wind having enough force to cause these similar shapes to align themselves similarly. And I can understand them being so difuse that they are nearly invisible most of the time. And I can understand that depending upon our viewpoint and the angle of a flat surface on one side of a crystal or dust particle the particles can suddenly become visible.

I can't understand why I can't introduce smoke particles to a vaccuume chamber and get them to accelerate to one side of the chamber when struck by man made equivalent of the solar wind. Hell, we should be able to see some effect of solar wind on debris outside any of our sattelites or even the shuttle. Since we can't, I am going to remain skeptical that this is what we are seeing happening on a comet.

Dan

Karl
2002-Apr-09, 09:40 AM
On 2002-04-09 02:11, dapted wrote:


But I did come up with another inane arguement. Put all the tails on a drawing of a comet and you have the Ion tail, the sodium tail, the hydrogen tail, and the dust tail. They are essentially, if I am getting this right, sifted components from the comet. The solar wind had sifted them like a screen sifts different sizes of gravel. Larger their area in relation to their mass, the closer they come to being "blown" straight behind the comet by the solar wind. {/quote]

The Ion tail is blown by the solar wind and neutral sodium is pushed by radiation pressure. The velocities can be measured by looking at the doppler shifts of light either emitted or reflected from them. If the light were reflected from a stationary ice or smoke particle, it wouldn't show the doppler shift.

http://www.aas.org/publications/baas/v25n2/aas182/abshtml/S1505.html

[quote]At some point in the comets orbit, it unfolds these tails like a japaneese fan. In order for all these things to happen you have to understand vastly complex explanations.

Well, it's a complex universe out there. . .

dapted
2002-Apr-10, 05:18 AM
Ok you did it again didn't you? You posted a link without reading it! Ha, I'm not the only one. <grin> Don't bother now, it was horrible. Didn't go anywhere. Doppler shift is very good at times and confusing at others. Take a look at doppler shift from a rainbow for instance. If you look at it from a doppler shift perspective, anytime you go from one band to the other it will give the appearance of a red shift or a blue shift depending on which way you move. Big light movement on a perfectly stable apparition.

If we are looking at refracted, or even reflected light which has had most of it's spectrum either bounced a different direction, or simply passed thru to outer space, we only get to see a tiny chunk of the spectrum. If we use sunlight as the baseline for a non moving particle and we see a full spectrum reflection we assume that particle is essentially standing still. But if it is missing part of the spectrum we say it has a doppler shift either to the red or the blue. But this doesn't take into account the possibility of a standing still, relatively speaking, particle which is only reflecting part of the spectrum.

Take an iceberg for example. If you doppler shift the light comming from it you would say it is moving because of the blue shift. Wrong!, it is just that blue is the only part of the spectrum not absorbed by the ice. If they want to doppler shift these particles fine, but take it with a big grain of salt.

PS. I agree it is a complex universe. But there is an old addage, when there are two possibilities, always choose the simpler one.

PS. I am pretty knowledgeable about doppler shift and electronics. Metrology specialist c/o USAF (study of fine measurements and calibration, nothing at all to do with the weather) and operating my own electronics and computer business for 30+ years. I used to calibrate radar guns etc. which use doppler extensively. I also have had extensive access to ionizing radiation sources which were used to calibrate many different types of dosimeters and other less known measurement equipmet. That is how I came to try to re-create movement of anything in a vacuume with ionizing radiations sources, which is what solar wind really is. But take that with a grain of salt too! I am proven wrong with excrutiating regularity. <BIG GRIN>

ToSeek
2002-Apr-10, 11:44 AM
On 2002-04-10 01:18, dapted wrote:
Doppler shift is very good at times and confusing at others. Take a look at doppler shift from a rainbow for instance. If you look at it from a doppler shift perspective, anytime you go from one band to the other it will give the appearance of a red shift or a blue shift depending on which way you move.

I think you misunderstand Doppler shift. A rainbow would not show a Doppler shift just from being red or blue. A Doppler shift is measured by finding a known set of emission or absorption lines that have been shifted toward a lower (red) or higher (blue) frequency and measuring the difference between the observed frequency and the expected one. (I've talked with astronomers who even state distances in terms of frequency shifts.) Otherwise, we would think that red stars are far away and blue stars are close when that's not necessarily the case.

GrapesOfWrath
2002-Apr-10, 11:51 AM
Doppler on icebergs? Are you talking about the speed of ice melting, or ocean drift speed? /phpBB/images/smiles/icon_smile.gif



On 2002-04-10 01:18, dapted wrote:
PS. I agree it is a complex universe. But there is an old addage, when there are two possibilities, always choose the simpler one.

There is a more modern adage, attributed to Einstein (http://www.ivf-et.com/capsule.html) (I didn't read that link either), "Make things as simple as possible but no simpler..."

Karl
2002-Apr-10, 12:22 PM
On 2002-04-10 01:18, dapted wrote:
Ok you did it again didn't you? You posted a link without reading it!

I read it, wished I could find a clearer example, but couldn't. Wish I could see the whole paper.


Ha, I'm not the only one. <grin> Don't bother now, it was horrible. Didn't go anywhere. Doppler shift is very good at times and confusing at others. Take a look at doppler shift from a rainbow for instance.

What doppler shift?


If you look at it from a doppler shift perspective, anytime you go from one band to the other it will give the appearance of a red shift or a blue shift depending on which way you move. Big light movement on a perfectly stable apparition.

Huh?


If we are looking at refracted, or even reflected light which has had most of it's spectrum either bounced a different direction, or simply passed thru to outer space, we only get to see a tiny chunk of the spectrum. If we use sunlight as the baseline for a non moving particle and we see a full spectrum reflection we assume that particle is essentially standing still. But if it is missing part of the spectrum we say it has a doppler shift either to the red or the blue.

Maybe you say that, but we don't say that, that is an absorbtion spectrum, not a doppler shift


But this doesn't take into account the possibility of a standing still, relatively speaking, particle which is only reflecting part of the spectrum.

Take an iceberg for example. If you doppler shift the light comming from it you would say it is moving because of the blue shift. Wrong!, it is just that blue is the only part of the spectrum not absorbed by the ice. If they want to doppler shift these particles fine, but take it with a big grain of salt.


I think you need to review what a Doppler Shift (http://www.astro.ucla.edu/~wright/doppler.htm) is.



PS. I agree it is a complex universe. But there is an old addage, when there are two possibilities, always choose the simpler one.

Known as Occam's (Ockham's) Razor. When faced with two possibilities which fit the facts, the simplest is generally the right answer.


PS. I am pretty knowledgeable about doppler shift and electronics. Metrology specialist c/o USAF (study of fine measurements and calibration, nothing at all to do with the weather) and operating my own electronics and computer business for 30+ years. I used to calibrate radar guns etc. which use doppler extensively. I also have had extensive access to ionizing radiation sources which were used to calibrate many different types of dosimeters and other less known measurement equipmet. That is how I came to try to re-create movement of anything in a vacuume with ionizing radiations sources, which is what solar wind really is. But take that with a grain of salt too! I am proven wrong with excrutiating regularity. <BIG GRIN>


And how do the radar guns work, using your definition of Doppler?

Duplicating solar wind conditions on earth is difficult to impossible with the best grade laboratory vacuum equipment, what were you using?

Fixed tag.

<font size=-1>[ This Message was edited by: Karl on 2002-04-10 08:25 ]</font>

dapted
2002-Apr-11, 01:58 AM
On 2002-04-10 08:22, Karl wrote:


On 2002-04-10 01:18, dapted wrote:
Ok you did it again didn't you? You posted a link without reading it!

I read it, wished I could find a clearer example, but couldn't. Wish I could see the whole paper.


Ha, I'm not the only one. <grin> Don't bother now, it was horrible. Didn't go anywhere. Doppler shift is very good at times and confusing at others. Take a look at doppler shift from a rainbow for instance.

What doppler shift?


If you look at it from a doppler shift perspective, anytime you go from one band to the other it will give the appearance of a red shift or a blue shift depending on which way you move. Big light movement on a perfectly stable apparition.

Huh?

Right. If you look at a rainbow and expect to see the reflected light of the sun it will appear to be shifted. Nobody in his right mind will do that, they know this is refracted light and missing most of the spectrum. But if they didn't know it, it would look very similar to light which is showing a doppler shift.


If we are looking at refracted, or even reflected light which has had most of it's spectrum either bounced a different direction, or simply passed thru to outer space, we only get to see a tiny chunk of the spectrum. If we use sunlight as the baseline for a non moving particle and we see a full spectrum reflection we assume that particle is essentially standing still. But if it is missing part of the spectrum we say it has a doppler shift either to the red or the blue.

Maybe you say that, but we don't say that, that is an absorbtion spectrum, not a doppler shift


But this doesn't take into account the possibility of a standing still, relatively speaking, particle which is only reflecting part of the spectrum.

Take an iceberg for example. If you doppler shift the light comming from it you would say it is moving because of the blue shift. Wrong!, it is just that blue is the only part of the spectrum not absorbed by the ice. If they want to doppler shift these particles fine, but take it with a big grain of salt.


I think you need to review what a Doppler Shift (http://www.astro.ucla.edu/~wright/doppler.htm) is.



PS. I agree it is a complex universe. But there is an old addage, when there are two possibilities, always choose the simpler one.

Known as Occam's (Ockham's) Razor. When faced with two possibilities which fit the facts, the simplest is generally the right answer.


PS. I am pretty knowledgeable about doppler shift and electronics. Metrology specialist c/o USAF (study of fine measurements and calibration, nothing at all to do with the weather) and operating my own electronics and computer business for 30+ years. I used to calibrate radar guns etc. which use doppler extensively. I also have had extensive access to ionizing radiation sources which were used to calibrate many different types of dosimeters and other less known measurement equipmet. That is how I came to try to re-create movement of anything in a vacuume with ionizing radiations sources, which is what solar wind really is. But take that with a grain of salt too! I am proven wrong with excrutiating regularity. <BIG GRIN>


And how do the radar guns work, using your definition of Doppler?

Duplicating solar wind conditions on earth is difficult to impossible with the best grade laboratory vacuum equipment, what were you using?

Doppler shift can be seen, heard and/or measured at any frequency. Put simply you send a signal at a known frequency toward an object. Then you measure the difference between what was sent and what was returned. Something moving toward you increases in frequency, something moving away from you decreases in frequency. You can use sound waves in water, or air or most any medium through which objects move and if you are close enough to hear the returned signal you can tell how fast it is moving and in which direction. Same with microwave frequencies and a radar gun.

Likewise you can do it with light. But whether is is sound, microwave or light, if you don't know what the baseline frequency is, or if the shape of the object you are trying to measure bounces the signal the wrong direction, or distorts it, you get faulty data in return.

Thus to measure the speed of particles moving thru space you have to assume that they are returning a full spectrum reflection. If only one portion of the spectrum is returned, you get a false return. It is a big assumption to believe you are getting a full return from such small objects. Especially so when you don't know for certain whether they are in a solid, liquid, gaseous, or plasmatic state.

As for the make and model of vacuume chambers and radiation source materials and targets we used thirty years ago forget it, I forgot that data long ago. But I remeber the experiments well enough to know that we were unsuccessfull. The tests we did with atomic clocks sent around the world west to east, versus east to west on the other hand were very successfull and well published. I tend to remember a lot about my/our successes but details escape me about the failures.

Dan



Fixed tag.

<font size=-1>[ This Message was edited by: Karl on 2002-04-10 08:25 ]</font>

ToSeek
2002-Apr-11, 01:11 PM
Doppler shift can be seen, heard and/or measured at any frequency. Put simply you send a signal at a known frequency toward an object. Then you measure the difference between what was sent and what was returned. Something moving toward you increases in frequency, something moving away from you decreases in frequency. You can use sound waves in water, or air or most any medium through which objects move and if you are close enough to hear the returned signal you can tell how fast it is moving and in which direction. Same with microwave frequencies and a radar gun.

Likewise you can do it with light. But whether is is sound, microwave or light, if you don't know what the baseline frequency is, or if the shape of the object you are trying to measure bounces the signal the wrong direction, or distorts it, you get faulty data in return.

Thus to measure the speed of particles moving thru space you have to assume that they are returning a full spectrum reflection. If only one portion of the spectrum is returned, you get a false return. It is a big assumption to believe you are getting a full return from such small objects. Especially so when you don't know for certain whether they are in a solid, liquid, gaseous, or plasmatic state.


Your first paragraph is good, your second paragraph is not so. As you point out, Doppler works for speed traps because you're using one specific frequency that only gets changed a little bit. If you get back blue light (say), you ignore it because you know it isn't what you were looking for.

However, it's not true that you need a full spectrum to detect a Doppler effect. All you need is enough of a spectrum to find identifiable absorption or emission lines. If you can identify them, you know where they're supposed to be (without the Doppler effect) and can measure the difference and therefore gauge the velocity.

dapted
2002-Apr-12, 04:14 AM
I see your point, and it is kind of the same. As you point out, those looking for a particular return throw out what they don't expect to see. It seems to work OK when we are talking about a few thousand miles per hour. But when we are talking about measuring speeds of 10% the speed of light, the phase shift becomes huge, so huge that absorption could account for the difference.

Here is another of my inane arguments. If any matter is accelerated to a significant fraction of the speed of light, it would have to experience a time shift of some sort. For the matter which is accelerated time would be going slower wouldn't it? Aren't we seeing matter accelerated to high percentages of the speed of light in the Ion tail? Shouldn't light emitted from plasing elements be phase shifted accordingly due to the perceived time difference? Or is it too small of a difference to be visibly recognizable?

Dan

Karl
2002-Apr-12, 10:44 AM
On 2002-04-12 00:14, dapted wrote:
I see your point, and it is kind of the same. As you point out, those looking for a particular return throw out what they don't expect to see. It seems to work OK when we are talking about a few thousand miles per hour. But when we are talking about measuring speeds of 10% the speed of light, the phase shift becomes huge, so huge that absorption could account for the difference.

Here is another of my inane arguments. If any matter is accelerated to a significant fraction of the speed of light, it would have to experience a time shift of some sort. For the matter which is accelerated time would be going slower wouldn't it? Aren't we seeing matter accelerated to high percentages of the speed of light in the Ion tail? Shouldn't light emitted from plasing elements be phase shifted accordingly due to the perceived time difference? Or is it too small of a difference to be visibly recognizable?

Dan


400kps = 4 x 10<sup>2</sup> x 10<sup>3</sup>=4x10<sup>5</sup>m/s

So 4x10<sup>5</sup>m/s/3x10<sup>8</sup>m/s = 1.3x10<sup>-3</sup> or about .1%

So we are well below where most people worry about relativistic corrections.

(I'm short on time the next few days and will be on travel for a week after that)

John Kierein
2002-Apr-12, 12:05 PM
Interesting discussion, but I want to know where the comet viruses are. Are they just in the nucleus, or are they in the dust tail,too? Or are they small enough to be in the sodium tail? When we pass through a comet tail, do we get the viruses or do have to be hit by one directly?

Firefox
2002-Apr-12, 12:07 PM
On 2002-04-12 08:05, John Kierein wrote:
Interesting discussion, but I want to know where the comet viruses are. Are they just in the nucleus, or are they in the dust tail,too? Or are they small enough to be in the sodium tail? When we pass through a comet tail, do we get the viruses or do have to be hit by one directly?


Eh? /:|

John Kierein
2002-Apr-12, 07:45 PM
Oh. In case you weren't aware of it, several people have suggested that new viruses or even other life forms are brought to earth via comets. Comets are black like carbonaceous chondrites that are known to contain amino acids and other organic and may even contain life. The late Sir Fred Hoyle suggested that comets could be a source of new viruses, he or someone suggested perhaps even AIDS. Some U. of Iowa space scientists have suggested all the water in the oceans comes from comets (See the book: The Big Splash).

Firefox
2002-Apr-13, 04:20 AM
To hazard an assumption, based on limited understanding (and straying a bit off-topic, might I add,) but wouldn't virii or bacterium find it difficult harming terrestrial life if it was from comets? I have heard of organic compounds arriving on comets, but nothing about whole unicellular organisms.


-Adam

dapted
2002-Apr-13, 05:00 AM
On 2002-04-13 00:20, Firefox wrote:
To hazard an assumption, based on limited understanding (and straying a bit off-topic, might I add,) but wouldn't virii or bacterium find it difficult harming terrestrial life if it was from comets? I have heard of organic compounds arriving on comets, but nothing about whole unicellular organisms.


-Adam


Conceivable but unlikely. If comets were formed by the colision of a magnificent scale, say something like a moon sized object striking a very liquid planet like earth, with all its varied life, the comets could be that small percentage of Ice and rock that wasn't vaporized, but were launched into solar orbit, and any organic material, including spores and viruses could concievably survive for millions or billions of years in near zero K temps, but even in that unlikly event you would think re-entry would snuf that out. Unless the comet piece was big enough for it's core to survive, and it was slowed down sufficiently to survive splashdown, and if the virus were from a lifeform it understood how to host itself in, and, and, and, at some point even I give up. Doubting Thomas has nothing on me. <grin>

Dan

<font size=-1>[ This Message was edited by: dapted on 2002-04-13 01:02 ]</font>

dapted
2002-Apr-13, 05:15 AM
On 2002-04-12 06:44, Karl wrote:


On 2002-04-12 00:14, dapted wrote:
I see your point, and it is kind of the same. As you point out, those looking for a particular return throw out what they don't expect to see. It seems to work OK when we are talking about a few thousand miles per hour. But when we are talking about measuring speeds of 10% the speed of light, the phase shift becomes huge, so huge that absorption could account for the difference.

Here is another of my inane arguments. If any matter is accelerated to a significant fraction of the speed of light, it would have to experience a time shift of some sort. For the matter which is accelerated time would be going slower wouldn't it? Aren't we seeing matter accelerated to high percentages of the speed of light in the Ion tail? Shouldn't light emitted from plasing elements be phase shifted accordingly due to the perceived time difference? Or is it too small of a difference to be visibly recognizable?

Dan


400kps = 4 x 10<sup>2</sup> x 10<sup>3</sup>=4x10<sup>5</sup>m/s

So 4x10<sup>5</sup>m/s/3x10<sup>8</sup>m/s = 1.3x10<sup>-3</sup> or about .1%

So we are well below where most people worry about relativistic corrections.

(I'm short on time the next few days and will be on travel for a week after that)


Right you are, I misplaced 2 decimal places, I think it was the spagetti sauce on the napkin that did it, thats my story and I, like the spot, am sticking to it. Usually napkins I doodle on are cleaner!