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DJ
2002-Jan-17, 09:08 PM
As our sun and planets move through space, I have to make an intuitive assumption that the space they are occupying is always new... but would it always be empty?

I've also read that the spiral arms of the Milky Way may tend to "bob" up and down a bit... not necessarily moving completely in line with the galactic plane.

So as I see the picture in my mind, our heliosphere is constantly moving into -- some other space -- which may have been previously occupied by something. So this all comes with a few questions/conclusions:

a) does the "something" get pushed out of the way by the bow shock of the heliosphere? If so, there would still be a dent in the heliosphere in some way, which it seems could have some measurable implications... especially if the shape of it changed dramatically

b) does the something get absorbed into the heliosphere? If so, could we see it? Could it affect orbits?

c) does the something get burned up by the sun? If so, could it change the characteristics of the sun?

Such thoughts haunt me because it occurs to me that while we may be able to predict some things about our space locale, this would bring so many variables into play any observation would only be current for say... a minute. Could we have entered an area in space where something previous causes the sun to burn slightly differently, thus causing some of the climate characteristics we've measured for the last few decades? The answer to that might be determined by looking for similar climate changes on other worlds.

Any provacative ideas on this?

Karl
2002-Jan-17, 09:33 PM
On 2002-01-17 16:08, DJ wrote:

So as I see the picture in my mind, our heliosphere is constantly moving into -- some other space -- which may have been previously occupied by something. So this all comes with a few questions/conclusions:

a) does the "something" get pushed out of the way by the bow shock of the heliosphere? If so, there would still be a dent in the heliosphere in some way, which it seems could have some measurable implications... especially if the shape of it changed dramatically

b) does the something get absorbed into the heliosphere? If so, could we see it? Could it affect orbits?

c) does the something get burned up by the sun? If so, could it change the characteristics of the sun?



There has been an assumed detection of the heliopause, the region where the heliosphere slams into the interstellar medium. The physics of this phenomena has been studied closely because the same effect occurs at the earth, when the solar wind meet the earth's magnetosphere.

The interstellar medium is so diffuse that it has no effect on the sun and planets.

http://vraptor.jpl.nasa.gov/voyager/vgrhelio_pr.html

Azpod
2002-Jan-18, 12:12 AM
On 2002-01-17 16:08, DJ wrote:
As our sun and planets move through space, I have to make an intuitive assumption that the space they are occupying is always new... but would it always be empty?

I've also read that the spiral arms of the Milky Way may tend to "bob" up and down a bit... not necessarily moving completely in line with the galactic plane.

So as I see the picture in my mind, our heliosphere is constantly moving into -- some other space -- which may have been previously occupied by something. So this all comes with a few questions/conclusions:

a) does the "something" get pushed out of the way by the bow shock of the heliosphere? If so, there would still be a dent in the heliosphere in some way, which it seems could have some measurable implications... especially if the shape of it changed dramatically

b) does the something get absorbed into the heliosphere? If so, could we see it? Could it affect orbits?

c) does the something get burned up by the sun? If so, could it change the characteristics of the sun?

Such thoughts haunt me because it occurs to me that while we may be able to predict some things about our space locale, this would bring so many variables into play any observation would only be current for say... a minute. Could we have entered an area in space where something previous causes the sun to burn slightly differently, thus causing some of the climate characteristics we've measured for the last few decades? The answer to that might be determined by looking for similar climate changes on other worlds.

Any provacative ideas on this?


The heliopause will push atoms in the interstellar medium out of the way, much like the megnetosphere pushes ions in the solar wind around the Earth. However, a solid object would have no problem punching through.

The only way that he Sun could absorb something from interstellar space that would change its characteristics would be if it was really, really massive-- gas giant sized, for instance, and it had either enough mass to beef up the mass of the Sun or radically different composition (a metal-rich stellar remnant, for instance).

Either way, such an object would be big enough to spell doom for us, even if it missed the Sun completely. A near-miss would send all of the inner planets into erratic orbits, not to mention the large amount of asteroid debris that would possibly be thrown into a collision course with us.

Fortunately, the chances of such an encounter are so remote that we could bet on the Sun reaching a ripe old age and burn out into a black dwarf before anything like that would happen.

Donnie B.
2002-Jan-18, 01:17 AM
The OP is rather reminiscent of the great science fiction novella "Brain Wave", by Poul Anderson.

The premise of that story was that the solar system passed into a region of space where the fundamental constants of nature were very slightly different. The most notable effect was an increase in the efficiency of the human brain. Suddenly toddlers were figuring out calculus on their own...

But the other responders are correct: there's no danger from the interstellar medium except the very unlikely prospect of encountering a very massive object. We're in far more danger from earth-crossing asteroids, and comets from the outer parts of our own solar system. But even that danger is fairly small.

ToSeek
2002-Jan-18, 01:39 PM
On 2002-01-17 20:17, Donnie B. wrote:
The OP is rather reminiscent of the great science fiction novella "Brain Wave", by Poul Anderson.

The premise of that story was that the solar system passed into a region of space where the fundamental constants of nature were very slightly different. The most notable effect was an increase in the efficiency of the human brain. Suddenly toddlers were figuring out calculus on their own...



Isn't there something similar in some of Vernor Vinge's novels? I seem to recall that the Earth was buried in some region where many things were more difficult than "normal," including thinking and space travel.

Russ
2002-Jan-18, 02:47 PM
On 2002-01-17 16:08, DJ wrote:
As our sun and planets move through space, I have to make an intuitive assumption that the space they are occupying is always new... but would it always be empty?

Despite what the SiFi writers would lead you to believe, space is spectacularly empty. Even the densest parts of our galaxy are 99.9% empty space. This is why astronomers predict that when the Andromeda and Milky Way galasies collide, there will be only a dozen or so stellar collisions despite 900 billion odd opportunities.


I've also read that the spiral arms of the Milky Way may tend to "bob" up and down a bit... not necessarily moving completely in line with the galactic plane.

I have also heard this to be true.


So as I see the picture in my mind, our heliosphere is constantly moving into -- some other space -- which may have been previously occupied by something. So this all comes with a few questions/conclusions:

a) does the "something" get pushed out of the way by the bow shock of the heliosphere? If so, there would still be a dent in the heliosphere in some way, which it seems could have some measurable implications... especially if the shape of it changed dramatically.

It is true that something gets pushed out of the way but it is A) mostly hydrogen & B) there is damn little of it (1000 trillion tons) spread over a cubic parsec or so.


b) does the something get absorbed into the heliosphere? If so, could we see it? Could it affect orbits?

A) yes, but VEEEEEEEERY little of it. B) Not so far. C) Not enought to notice.


c) does the something get burned up by the sun? If so, could it change the characteristics of the sun?

A) Just the astroids & comets that are massive enough to make it through the solar system. B) Not in the time span the human race will be around.


Such thoughts haunt me because it occurs to me that while we may be able to predict some things about our space locale, this would bring so many variables into play any observation would only be current for say... a minute.

The human life span (i'll say 100yrs) is so fleetingly short on a cosmic scale that talking about obeservations in terms of minutes is pointless. To Wit: Comet Hale-Bopp was discovered out by Jupiter's orbit. Even traveling an average 66 miles per second (237600 mph)it took two years to even get close to Earths orbit. That was something that was already inside our solarsystem.


Could we have entered an area in space where something previous causes the sun to burn slightly differently, thus causing some of the climate characteristics we've measured for the last few decades?

A) As some one above said it would take something a major fraction of the Suns mass to do this and we'd have noticed that kind of thing arrive. B) The sun goes throught normal cycles and occelations. This is in all likelyhood what is causing whatever climate changes we have noticed. It is human conciet to believe it is us.


The answer to that might be determined by looking for similar climate changes on other worlds.

This is possible but the conditions on other planets are soooooo different that it would be very risky to try to draw parrallels.


Any provacative ideas on this?

I have read that our system is headed for a nebula about two LY away. There is some concern that if the nebula density is high enough, it may block a significant amount of Sun light causing climate problems on Earth. This possibility is not on the top of my worry list as it will be several thousands of years before we get there. /phpBB/images/smiles/icon_wink.gif

I love this stuff, don't you?

_________________
Lighten up! I'm here for the fun of it.


<font size=-1>edit to correct code.</font>
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<font size=-1>[ This Message was edited by: Russ on 2002-01-18 09:52 ]</font>

<font size=-1>[ This Message was edited by: Russ on 2002-01-18 09:58 ]</font>

Silas
2002-Jan-18, 04:36 PM
On 2002-01-18 08:39, ToSeek wrote:
Isn't there something similar in some of Vernor Vinge's novels? I seem to recall that the Earth was buried in some region where many things were more difficult than "normal," including thinking and space travel.



Yes: "A Fire Upon the Deep." Fun novel!

(Vinge has recently retired from teaching math at San Diego State University, where I majored in math -- and drinking -- )

There's also Delaney's "The Einstein Intersection," although it's more "social science fiction" (or fantasy) than hard sf.

Larry Niven's "Raft" also comes to mind, and Asimov's, too, wrote a book about alternate laws of physics intruding into our space. ("Caves of Steel?")

Silas

ToSeek
2002-Jan-18, 05:10 PM
Asimov, too, wrote a book about alternate laws of physics intruding into our space. ("Caves of Steel?")


The Gods Themselves?

(Caves of Steel was the first of his mystery novels with the human-robot detective team. A classic, too, but not the same.)

_________________
"... to strive, to seek, to find, and not to yield." - Tennyson, Ulysses

<font size=-1>[ This Message was edited by: ToSeek on 2002-01-18 12:10 ]</font>

Azpod
2002-Jan-18, 06:44 PM
On 2002-01-18 09:47, Russ wrote:
I have read that our system is headed for a nebula about two LY away. There is some concern that if the nebula density is high enough, it may block a significant amount of Sun light causing climate problems on Earth. This possibility is not on the top of my worry list as it will be several thousands of years before we get there. /phpBB/images/smiles/icon_wink.gif

I love this stuff, don't you?


???!!! Where did you hear this??? So this nebula is closer to us than the nearest stars? How big it is? How much mass does it contain? Is it visible from Earth at all...?

Last I heard that there is a whole lot of nothing between us and the nearest star. If someone's heard something else, please let me know; I'd be interested in learning more.

Spaceman Spiff
2002-Jan-19, 01:46 AM
The heliopause will push atoms in the interstellar medium out of the way, much like the megnetosphere pushes ions in the solar wind around the Earth. However, a solid object would have no problem punching through.

The only way that he Sun could absorb something from interstellar space that would change its characteristics would be if it was really, really massive-- gas giant sized, for instance, and it had either enough mass to beef up the mass of the Sun or radically different composition (a metal-rich stellar remnant, for instance).

Either way, such an object would be big enough to spell doom for us, even if it missed the Sun completely. A near-miss would send all of the inner planets into erratic orbits, not to mention the large amount of asteroid debris that would possibly be thrown into a collision course with us.

Fortunately, the chances of such an encounter are so remote that we could bet on the Sun reaching a ripe old age and burn out into a black dwarf before anything like that would happen.



The heliosphere does not exert an infinite pressure. If the solar system were to plow into a dense interstellar cloud, the latter's pressure would collapse the heliosphere into a much smaller volume - perhaps small enough that interstellar matter (e.g. hydrogen, helium gas, etc) could be accreted onto the sun and even the planets.


<font size=-1>[ This Message was edited by: Spaceman Spiff on 2002-01-18 20:48 ]</font>

Russ
2002-Jan-22, 11:46 PM
On 2002-01-18 13:44, Azpod wrote:

???!!! Where did you hear this???

Can't remember, looooong time ago, probably not accurate, probably from Discover Mag. or other =ly reliable source. I should have put a /phpBB/images/smiles/icon_wink.gif after that claim as it was not intended to be serious. I thought the ludicrusnss would be self evident. I BLEWIT.

As I recall the article, we were still 50-60K years away and that was a good 8 or 9 years ago. The clock is ticking. /phpBB/images/smiles/icon_lol.gif