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Jerod S. V2.0
2004-Jun-05, 06:39 AM
Hello everyone...

First, for the record, I was posting on this BB a year ago at the height of the PX2003 non-event. I was posting under the user name 'Jerod S.' However, it's been a while and my previous account seems to be deactivated. Tried to get a new password a couple weeks back (as I'd long since spaced the old one) but didn't have any luck getting that to cooperate with me. Since I hate to complain to webmasters 'cause they have enough to worry about, I've simply registered anew under a variation on my previous user name. Sorry about the confusion this creates (if any) -and hopefully I won't be kicked off the board outright for it...

Now, the item I really wanted to post about!

I was outside at 11:30 PM on what is now last night and happened to catch what is probably *the* coolest 'shooting star' I've ever seen. Everything I've seen before has resembled a star in terms of the coloration. But this one clearly had a green tint to it. Not only that, but it appeared in the sky for roughly 5-6 seconds as opposed to the usual 1-3 seconds. (All times are rough estimates on my part...)

Two questions:

1) Does the elemental composition of 'shooting star' burning up in the atmosphere effect the color that we see? (Obviously the green color mentioned above threw me off, hence the question.)

2) I've heard (correct me if I'm wrong) that most of the 'shooting stars' we see are somewhere between the size of a grain of sand and the average grape -or thereabouts. Would I be correct in guessing the one I saw last night hung around a bit longer 'cause it was a little larger and therefore took a little longer to burn up in the atmosphere?

I realize this isn't a terribly exciting thread, but...just curious as to why I saw what I saw last night. I'm pretty certain it wasn't Venus, a UFO or an undigested bit of ham, for the record... :lol:

kenneth rodman
2004-Jun-05, 07:05 AM
ok im not an authority but your probably right in assuming the size was a bit larger because of how long it lasted. As to what the size of most shooting stars are vs the one you saw, I thinking that shooting stars are larger than grains of sand or even grapes as to how much larger ? shrug

and concerning the color of light you saw; could be due to the materials that made up that particular shooting star, could be due to atmospheric conditions. Dunno.

Crazieman
2004-Jun-05, 07:46 AM
Green ones are rare, but happen. There was a spectacular green one a few years back.

It is indeed based on composition, density, size, speed, and to some extent, atmospheric condition.

jt-3d
2004-Jun-05, 08:20 AM
I've seen a green one too, a couple years ago. What burns green? Somebody told me copper but I don't know.

PhantomWolf
2004-Jun-05, 09:47 AM
I've seen a green one too, a couple years ago. What burns green? Somebody told me copper but I don't know.

Copper is the classic, though Barium also burns green.

orangeSCT
2004-Jun-05, 01:12 PM
Fireballs are always fantastic to watch. I've stayed up many nights during the annual meteor showers hoping for a few good fireballs (usually to be disappointed). Congrats on seeing this one.

Russ
2004-Jun-05, 06:24 PM
IIRC the light you see is from the ionization of the atmosphere ahead of the meteor, not from the meteor itself. They all look white to me so colorization must be from some other factor. If you were to see any of the material ablating from the object it would be in the form of smoke astern of the object.

Regarding size: It does matter. No, No, No, I'm not going there! :-? The big ones tend to last longer as they enter the atmosphere BUT, that is dependent on the material from which it is made. A bigger carbinasious condrite will burn up quicker than a smaller nickle-iron. There are other factors, angle of entry, differential velocity, etc. :)

Kaptain K
2004-Jun-05, 06:32 PM
1) Does the elemental composition of 'shooting star' burning up in the atmosphere effect the color that we see? (Obviously the green color mentioned above threw me off, hence the question.)
Although most meteors are white, I've seen several yellow ones, a few red ones, a couple of blue ones and yes one very bright and brilliant green one! :o To answer your question, yes composition does play a part in determining the color of the meteor. Copper and barium have been mentioned. Oxygen (from the atmosphere) might also contribute.


2) I've heard (correct me if I'm wrong) that most of the 'shooting stars' we see are somewhere between the size of a grain of sand and the average grape -or thereabouts.
The faintest meteors are more on the order of the size of a particle of cigarette smoke! "Grain of sand" would be typical of a run of the mill meteor. A meteoroid the size of a grape would produce a spectacular fireball!

Would I be correct in guessing the one I saw last night hung around a bit longer 'cause it was a little larger and therefore took a little longer to burn up in the atmosphere?

The time that a meteor is visible is more a function of geometry (how steeply it enters the atmosphere) and its speed. The speed of a meteor varies from 11 Km/sec (Earth's escape velocity) to over 100 Km/sec.

Jerod S. V2.0
2004-Jun-06, 05:39 AM
Thank you to all of you who replied to my inquiry.

I can't begin to guess about atmospheric conditions when I saw the shooting star in question. The closest to that I can offer is that it was clear outside. Not overcast, no blatantly visible high clouds in the vicinity where Mr. Green came down. I realize that's almost (and may outright be) a seperate issue from atmospheric conditions, but...

It was just rather cool. In my three decades on planet Earth I've only ever seen the white, very brief variety. Had a few instances where I could actually hear the thing burn up. :o Also cool, but mildly unnerving. Began awaiting the impact on my left temple or something. :roll:

beskeptical
2004-Jun-06, 08:08 AM
I'm pretty sure Russ is right here. The color is the result of ionizing particles in the atmosphere. The altitude of the burn is what changes the colors. If the meteor is coming in at an steep angle or more parallel to the horizon, it affects the rate of accumulating friction and subsequently the altitude you see the flash.

Single meteors can come in at any angle. Meteor showers are affected as the Earth turns and moves along its orbit. Sometimes we are catching up to the dust trail and sometimes it is catching up to us. Sometimes we are turning into a dust trail so meteors are coming over the horizon and sometimes they are coming in directly overhead.

A larger rock will make it further into the atmosphere. There it is hitting way more air molecules thus way more friction. That's when you get a fireball. And if it makes it all the way to a point where the friction causes the meteor to explode, you get daylight for a few seconds like we had in WA the other night. People's 24 hour cameras recorded not just a little light, but you could actually see distant mountain ranges. :o

Too bad I was asleep. Oh well.

Anyway, some meteors leave trails of greenish colored smoke. It has to include some of the meteor. I'm not sure if stony meteors or iron meteors leave different smoke colors. The vast majority of meteorites that reach the ground are stony, despite the fact that most of the ones that are found are iron. So the majority of meteors are stone though there are several varieties. Anyway, back to the topic, its the atmosphere not the meteor that provides the color.

Alcoraiden
2004-Jun-08, 09:28 PM
I saw a big yellow fireball last year that left a yellow trail. So the altitude affects the color? What's the color order, highest to lowest, anyone know?

ToSeek
2004-Jun-08, 11:34 PM
Composition does matter (http://www.corvus.com/faq/aa01faq2.htm)


The composition of the meteoroid plays an important part in the observed colors of a meteor, with certain elements displaying signature colors when vaporized. For example, sodium produces a bright yellow color, nickel shows as green, and magnesium as blue-white. The velocity of the meteor also plays an important role, since a higher level of kinetic energy will excite the atoms to a higher degree. Slow meteors are often reported as red or orange, while fast meteors frequently have a blue color. Due to the nearly identical composition and velocity of meteors belonging to a particular shower, several showers are known for their characteristically colored meteors.

Celestial Mechanic
2004-Jun-09, 04:10 AM
Considering how long it lasted (you said 5-6 seconds), maybe it was a re-entering satellite that you saw? In Oklahoma I once saw what I thought was a fireball very low in the northern sky for several seconds. The paper the next day reported that a Soviet communication satellite had re-entered over Nebraska causing phone calls to police departments all over Kansas and Nebraska.

SiriMurthy
2004-Jun-09, 06:05 PM
I have seen green streaks in the sky. None of them lasted 5 - 6 seconds. They were all like 2 or 3 seconds max.

Kaptain K
2004-Jun-09, 06:19 PM
August 10, 1972 - Daylight fireball caught on film. 26 seconds of film after first being noticed!

http://www.maa.agleia.de/Comet/Other/1972.html

Thompson
2004-Jun-09, 08:32 PM
Ooo, wow, green meteor!? Cool. I still have yet to see one... even during a shower. :( , Tho i did see a nice orange-yellow fireball a few years back that lasted quite a while. \:D/ went almost the entire length of the sky, tho i cant confirm that as by the time i looked up she was already burning up.

milli360
2004-Jun-09, 08:37 PM
August 10, 1972
The fireball over the Grand Tetons (http://comets.amsmeteors.org/meteors/1972.html)!

ToSeek
2004-Jun-09, 09:00 PM
I have seen green streaks in the sky. None of them lasted 5 - 6 seconds. They were all like 2 or 3 seconds max.

I saw a bright green fireball once.

Avatar28
2004-Jun-09, 10:21 PM
I have seen green streaks in the sky. None of them lasted 5 - 6 seconds. They were all like 2 or 3 seconds max.

I saw a bright green fireball once.

Yeah, me too. Didn't last but 2-3 seconds probably though. I didn't realize that green was unusual, I thought it was the norm. It's about the only one I ever remember seeing. Well, no. Once I saw one come down, seemed to level out a bit (maybe even head back up slightly), then head back down again. Dunno if it skipped on the atmosphere or what. It wasn't an airplane, though. Way too fast for that. I do know that it didn't look nearly as big or spectacular as the other fireball I saw.

S Raynor
2006-Jan-11, 11:05 PM
Hi!
I'm in the South of England, UK and have just seen a green shooting star! It was awesome! lasted about 5 seconds, was really bright and was heading towards London, lol.

I thought it was weird so searched on google to find out why it was green and found this thread..

Very informative, thanks!

It was real bright though, at first I thought it was a firework or a flare, but it was too high, went too far and too fast to be either.

Before it disappeared it got much slower and probably 4 times as bright than when it was going faster.


Amazing!

Stu :D

Weird Dave
2006-Jan-11, 11:35 PM
Hi!
I'm in the South of England, UK and have just seen a green shooting star! It was awesome! lasted about 5 seconds, was really bright and was heading towards London, lol.

I thought it was weird so searched on google to find out why it was green and found this thread..

Very informative, thanks!

It was real bright though, at first I thought it was a firework or a flare, but it was too high, went too far and too fast to be either.

Before it disappeared it got much slower and probably 4 times as bright than when it was going faster.


Amazing!

Stu :D
Yippee, I wasn't seeing things! I saw this and thought it might be a firework too. But I decided to tell the British Astronomical Association about it, because they collect information about these things: http://www.britastro.org/meteor/obs_fireballs.html

If anyone else saw this, you might want to contact the BAA's meteor section (email address is here: http://www.britastro.org/info/meteor.html) so that they can collate the reports. Maybe, if lots of accurate reports come in, they can work out where it would have landed and find a meteorite!

For your info, here's the report I sent in:

Dear Mr Bone,

I think I might have seen a bright green meteor near Oxford.

I was walking North-West over Magdalen Bridge [Lat: 51:45:04N (51.751)
: Lon: 1:14:45W (-1.2459)] at about 10:40pm when I saw it on my right
(to the North-East). It was bright green, and split into about three
pieces as it fell. I only saw it briefly (for about half a second)
before it faded. I saw it falling at a steep angle, and from my
viewpoint it was heading North West. It was lowish in the sky (but I
can't guess the angle I'm afraid), and I have no idea of the distance.

I'm not sure what it was - it is possible that I only saw a firework.
However, all three pieces were falling on the same path (i.e. not like
a firework shower) and I heard no noise. It was moving relatively
slowly (relative to normal meteors, but much faster than a plane).

I don't want to send you off on some wild goose chase, but I thought
it worth contacting you just in case other people reported it too - so
that you might be able to triangulate the position of any surviving
fragments.

Thank you,

pasha582
2006-Jan-16, 10:10 PM
Copper is the classic, though Barium also burns green.

Both copper and barium should be quite rare in interplanetary space. Copper was chosen to smack comet Temple 1 simply because the copper atomic absorbtion lines could be subtracted out to reveal the composition of the asteroid--and copper is cheaper than even rarer metals such as gold or platinum.

Aluminum burns bright white. What colors do silicon and sulfur burn?

Fr. Wayne
2006-Jan-16, 11:59 PM
Atomic Oxygen burns green and may be a reaction with the atmosphere of either the temperature of the fireball or its actual chemical composition

zorbo
2006-Jan-18, 08:31 PM
Ive had a similar experience last year in summer. We were setting up our little telescope on a hill outside town near the Alps mountains.

I had never seen sizeable shooting stars of any color before. Even though I had always had a latent interest into astronomy as a science, I had just recently gotten into "practical astronomy" / star gazing because my wife had given me that telescope as a birthday gift.

Just when we were shooting north with the telescope to get it aligned, we saw a very bright green shooting star (in the West/NW). It seemed to last forever, I would immediately have guessed 5 or more seconds, but in retrospect it was really probably only one or two seconds, it was just that it was so spectacular that it seemed to last very long at that time.

Now here comes the tricky part.

It was distinctly green...a rich, beautiful green... but towards the end, when it was near the horizon, this was replaced by red. In the end it was red. Not just faint or greenish red but red in the same way that SOS sea signal candles burn off a bright red.
I was very happy that my wife saw it too because I would have thought I was seeing things.

It was so bright and intense that instinctly I waited for a loud impact noise. It was just that it appeared so big and powerful and near. Nonsense, of course, but in that moment I was instinctly preparing for a loud bang.
Of course there was no impact or other noise at all.

I would like to hear what your take on this is.

sincerely,
z.


p.s.: btw, I havent seen any more sizeable shooting stars of any kind ever since, I am also especially unlucky at catching those meteor showers.

Eyes open
2011-Feb-01, 11:47 PM
Never really had an interest in stars or astronomy untill last night.

12:21am looked up as I was discarding some water onto the lawn, less than a kilometer from the house a bright green light desended at a 45 degree angle. Saw it for all of 3 to 4 seconds. Can't have been a plane as it would have impacted due to its speed, angle and distance from the ground (wasn't the typical movement of an aircraft). First thoughts were it's some sort of falling star? but a bright green one!!!

Glad I found this blog, now believe it was a falling meteroite after reading your posts.

Spent two hours the next day driving around the countryside looking for a possible crater/reminants/anything as it was large and very low when I lost eye contact with it as I have trees surrounding the house.

After no success come to believe must have finished burning up or desended into the estuary.

Certainly some sight, shame I live in a rural area as hard to say others would have seen it. But no halo effect, no tail, just like a fast moving bright circular light.

Warkworth, New Zealand

Swift
2011-Feb-02, 03:32 AM
Hi Eyes Open, welcome to BAUT. I've only seen a green one once, nice "catch". And though it was bright, it might not actually have made it to the ground, or might be very tiny. Meteors are a lot smaller than people think. The typical ones during a meteor shower are the size of grains of sand.

Jens
2011-Feb-02, 05:24 AM
I've also only seen a green meteor once, and it was a big fireball. I think maybe that the small ones appear white because I don't see them long or well enough to be able to make out the color correctly.

astromark
2011-Feb-02, 05:51 AM
Welcome... Yes, last night right across most of New Zealand it was a perfect night for astronomy. I did spend just five hours observing and had my back to your object.. ( saw nothing at 12.21am...) I was recording images of 47 tuc.
From your description I can only say that a green bright fast moving object is not so rare.. By that I comment to have seen three over a number of years... small, metallic, entry and burn. If you did not hear it or a sonic BOOM... chances are it did not get below 35,000 ft., and yes. Most objects re entering and been seen are no bigger than a marble...or grains of sand.

nota
2011-Feb-02, 07:57 AM
I wonder if speed and temperature has a role in color
I know iron/steel will start dull orange go to red yellow and finally white hot as it is heated
maybe blue or green are ever higher temperature

I have seen a very very bright green fireball over the lights of the orange bowl at a game
and a blue one against the ocean sky

eburacum45
2011-Feb-02, 08:52 AM
As Fr Wayne noted above, the most likely cause of the green colour is atmospheric oxygen. In an aurora oxygen glows a nice mid-green: the green colour in many meteors seems to have a similar origin.

Combustion of copper or other metals is unlikely to be the cause of the commonest green coloured meteors, but might sometimes be significant.

slang
2011-Feb-02, 10:55 PM
12:21am looked up as I was discarding some water onto the lawn, less than a kilometer from the house [...]

Congrats on catching such a great event! But I wonder how you concluded that it was less than 1 km away? Or were you less than 1 km away from the house?

Eyes open
2011-Feb-03, 10:33 AM
I was standing on the balcony at the time. It's true, I agree, it's hard to judge the distance of an object in the sky especially when I had nothing to compare it with. Having said that-you can easy judge the difference between 50 meters, 500 meters, and 1000 meters when someone is flying a kite, even though you may not have seen the kite up close. But agreed the further away the object is the harder it is to discern the exact distance from you.

The comment about a sonic boom:
Not that I've ever heard one or know how loud it is. The door was shut before I went outside and witnessed the object. The point is that my house is on top of a hill (Should get a map with contours on it so can get exact elevation) overlooking the coastline. If I picture a horizontal line running out at eye level and judge a measurement to the top of the tree line where I lost sight of the object, it's give or say a 20 degree angle. If the object was one kilometer from where i was standing, remembering my house is elevated pehaps 50 to 100 meters, i think the object was very low to the ground before I lost sight of it. Hope this makes sence. But your right it all comes down to how far away it was.

Another thing is that:

The distance it travelled across the sky also lead me to believe it was under one kilometer away. If it was say 10 kilometers away, I don't think it could have covered so much distance in such a small amount of time unless it's speed was SUPER FAST and the object was larger?

Like standing at the edge of a highway and watching the cars go past-than if you stand 2 kilometers back from the highway, the cars don't cover the same amount of your vision even though there travelling at the same speed...Bad analogy but I think you know what I'm trying to get at.The further back you are, the less it looks as though the cars/object is moving across your vision.

IsaacKuo
2011-Feb-03, 03:36 PM
Shooting stars enter the atmosphere at over 10 kilometers per second. They do indeed travel SUPER FAST. If you saw it for more than a tenth of a second, it was more than a kilometer away.

eburacum45
2011-Feb-03, 10:55 PM
Most meteors are very high, and very far away. That meteor may easily have been fifty, 100 miles way or more, depending on its angle.

Eyes open
2011-Feb-04, 04:44 AM
When you say most, can you give a rough estimate.


Cheers
Eyes open.

slang
2011-Feb-05, 01:54 PM
I was standing on the balcony at the time. It's true, I agree, it's hard to judge the distance of an object in the sky especially when I had nothing to compare it with. Having said that-you can easy judge the difference between 50 meters, 500 meters, and 1000 meters when someone is flying a kite, even though you may not have seen the kite up close. But agreed the further away the object is the harder it is to discern the exact distance from you.

In the dark it is very difficult to guess a distance for something that is basically just a lightsource, even at much, much closer ranges than 1 km.


The distance it travelled across the sky also lead me to believe it was under one kilometer away. If it was say 10 kilometers away it could not have covered so much distance in such a small amount of time unless it's speed was SUPER FAST and the object was larger.

What would you consider "SUPER FAST"? Compared to cars? Airplanes? Rockets? All of them pathetic slowpokes compared to meteors :)


Major Meteor Showers (2010-2011)

Delta Aquarids
Meteor Velocity: 42 kilometers per second (26 miles per second)

Perseids
Meteor Velocity: 61 kilometers (38 miles) per second

Orionids
Meteor Velocity: 68 kilometers (42 miles) per second

Leonids
Meteor Velocity: 71 kilometers (44 miles) per second

Geminids
Meteor Velocity: 35 kilometers (22 miles) per second

Quadrantids
Meteor Velocity: 41 kilometers (25.5 miles) per second

Lyrids
Meteor Velocity: Lyrid meteors hit the atmosphere at a moderate speed of 48 kilometers (30 miles) per second. They often produce luminous dust trains observable for several seconds.

Eta Aquarids
Meteor Velocity: 66 kilometers (44 miles) per second

source (http://www.jpl.nasa.gov/news/news.cfm?release=2010-119)

Jeff Root
2011-Feb-05, 05:02 PM
Most meteors are very high, and very far away. That meteor may
easily have been fifty, 100 miles way or more, depending on its angle.


When you say most, can you give a rough estimate.
Practically all.

I have seen hundreds of meteors, probably over a thousand, and
I've never seen one that lasted more than about 1.5 seconds.
Chances are that every single one of them burned up higher than
70 kilometers above the ground. If I saw a meteor 70 km above
the ground, and it was 45 degrees up from the horizon, it would
be 100 km away from me.

The minimum speed for a natural meteor is about 10 km / s.
Small meteors -- the meteors we see all the time -- are slowed
very rapidly by the atmosphere. They generally burn up within
a second or two. The meteors in meteor showers come from
comets, and usually have very high speeds, as shown in slang's
list. I've seen Leonid meteors zoom rapidly across the sky, in
a very long path, but lasting only about a second. "Smoke" trails
from many of those meteors were visible for several minutes.

If your meteor did last as long as 3 to 4 seconds, it may have
been very high in the atmosphere, where the air drag is not as
great, so meteors do not burn up as quickly. The more nearly
vertically a meteor falls, the more rapidly it enters the denser
atmosphere, so the more rapidly it slows down and/or burns up.

A meteor seen 20 degrees above the horizon could easily be
250 km away, and smaller than a kiwifruit.

-- Jeff, in Minneapolis

swampyankee
2011-Feb-05, 05:04 PM
Has anybody pointed a spectroscope at a meteor trail and reported the results?

slang
2011-Feb-05, 11:06 PM
Has anybody pointed a spectroscope at a meteor trail and reported the results?

A quick search (http://adsabs.harvard.edu/cgi-bin/nph-basic_connect?version=1&qsearch=meteor+spectrograph) for "meteor spectrum" and "meteor spectograph" gives several promising papers.

Eyes open
2011-Feb-06, 12:47 PM
Appreciate the info

Don't wish to carry on more than I should about this, but how's the idea that the object was falling at a 45, yet was travelling towards me ? as apposed to one shooting across the sky.

Jeff Root
2011-Feb-06, 10:25 PM
That's a strong possibility. About a 50-50 chance that it was
headed towards you.

-- Jeff, in Minneapolis

astromark
2011-Feb-07, 01:42 AM
Recorded back in 2002 ( not trusting dodgy memory ) Just a 100 km or so away from here a Day light Bollard.. with air burst explosion and trail.. It made the news and was filmed from much further away.. I was inside a shopping mall nearly 200 km south and it felt like a moderate earthquake followed by a very deep and loud 'BOOM !' which rattled windows.
The object it was revealed was not much larger than the ball being used today in the Super Bowl...
only this one went off with such force... Study of the images from that film showed it to be reduced to smoke...at just under 30,000 ft.. Nothing but sound and smoke...reached Earth. The local farming community of Waverley near to Hawera NZ were worried it was a aircraft explosion. It was not. The film was taken from Nelson and no sound reached that location.
As astronomers world wide... I would like the term shooting star. Removed from descriptions... These things are never that.