Explanation: Meteors can be colorful. While the human eye usually cannot discern many colors, cameras often can. Pictured is a Geminid captured by camera during last week's meteor shower that was not only impressively bright, but colorful. The radiant grit cast off by asteroid 3200 Phaethon blazed a path across Earth's atmosphere longer than 60 times the angular diameter of the Moon. Colors in meteors usually originate from ionized elements released as the meteor disintegrates, with blue-green typically originating from magnesium, calcium radiating violet, and nickel glowing green. Red, however, typically originates from energized nitrogen and oxygen in the Earth's atmosphere. This bright meteoric fireball was gone in a flash -- less than a second -- but it left a wind-blown ionization trail that remained visible for several minutes, the start of which can be seen here.
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Wed Dec 19, 2018 4:27 pm
by Odysseus
Antony Rawlinson wrote: ↑Wed Dec 19, 2018 12:36 pm
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
I was a little disappointed as well, but it also made me smile.
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Wed Dec 19, 2018 4:37 pm
by Odysseus
It's beautiful to see how the "radiant grit" makes it look like a space-feather.
Antony Rawlinson wrote: ↑Wed Dec 19, 2018 12:36 pm
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
Antony Rawlinson wrote: ↑Wed Dec 19, 2018 12:36 pm
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
I was a little disappointed as well, but it also made me smile.
Just to be clear (if I'm right) I believe the caption was simply referring to the APOD itself when noting
"... a wind-blown ionization trail ... the start of which can be seen here."
whereas, if they had meant for you to follow a link to find a better image of the start of the trail, it would have been best marked up as:
"... the start of which can be seen here."
Besides, there were two good links to ionization tails/trails/trains already in that sentence.
Antony Rawlinson wrote: ↑Wed Dec 19, 2018 12:36 pm
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
I was a little disappointed as well, but it also made me smile.
Just to be clear (if I'm right) I believe the caption was simply referring to the APOD itself when noting
"... a wind-blown ionization trail ... the start of which can be seen here."
whereas, if they had meant for you to follow a link to find a better image of the start of the trail,
it would have been best marked up as: "... the start of which can be seen here."
‘All right,’ said the Cat; and this time it vanished quite slowly, beginning with the end of the tail,
and ending with the grin, which remained some time after the rest of it had gone.
‘Well! I’ve often seen a cat without a grin,’ thought Alice; ‘but a grin without a cat!
It’s the most curious thing I ever saw in my life!’
https://www.etymonline.com/word/see#etymonline_v_23104 wrote:
<<SEE (v.) Old English seon "to see, look, behold; observe, perceive, understand; experience, visit, inspect" (past tense seah, past participle sewen), from Proto-Germanic *sehwanan (source also of Old Saxon, Old High German sehan, Middle High German, German sehen, Old Frisian sia, Middle Dutch sien, Old Norse sja, Gothic saihwan). Thus see might originally mean "follow with the eyes."
Used in Middle English to mean "behold in the imagination or in a dream" (c. 1200), "to recognize the force of (a demonstration)," also c. 1200. Sense of "escort" (as in to see (someone) home) first recorded 1607 in Shakespeare. Meaning "to receive as a visitor" is attested from c. 1500. Gambling sense of "equal a bet" is from 1590s. See you as a casual farewell first attested 1891. Let me see as a pausing statement is recorded from 1510s.>>
Antony Rawlinson wrote: ↑Wed Dec 19, 2018 12:36 pm
The link purporting to show the start of the ionisation trail, under the text "can be seen" is a bit of a disappointment. Is it April 1?
I was a little disappointed as well, but it also made me smile.
Just to be clear (if I'm right) I believe the caption was simply referring to the APOD itself when noting
"... a wind-blown ionization trail ... the start of which can be seen here."
whereas, if they had meant for you to follow a link to find a better image of the start of the trail, it would have been best marked up as:
"... the start of which can be seen here."
Besides, there were two good links to ionization tails/trails/trains already in that sentence.
Thanks, Mark, I really appreciate it!
Although the kitten was sweet, too.
Ann
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Thu Dec 20, 2018 5:33 am
by MarkBour
Ann wrote: ↑Thu Dec 20, 2018 4:52 am
Thanks, Mark, I really appreciate it!
Although the kitten was sweet, too.
Ann
Any time, Ann. I thought you might remark on the colors in this image, which I think were quite beautiful.
Perhaps no commentary was needed, but I'm not sure if any processing was needed to end up with those rich colors.
Of course there's a band called "Meteor Cat" which can be seen here.
Ann wrote: ↑Thu Dec 20, 2018 4:52 am
Thanks, Mark, I really appreciate it!
Although the kitten was sweet, too.
Ann
Any time, Ann. I thought you might remark on the colors in this image, which I think were quite beautiful.
Perhaps no commentary was needed, but I'm not sure if any processing was needed to end up with those rich colors.
Of course there's a band called "Meteor Cat" which can be seen here.
Indeed, I agree that the colors of the meteor trail in this APOD were quite beautiful!
The reason why I didn't comment was that I thought I had made a good point about the colors of meteors in a recent APOD discussion thread. But when I checked my post, the picture I posted had disappeared.
So here is another version of the picture I posted earlier. Unfortunately I haven't found a reliable source for the picture. But let's hope that the picture doesn't disappear!
My impression is that many meteors are aqua-colored apparently from iron. And this picture suggests that the green color of parts of the meteor trail might result from magnesium.
Ann wrote: ↑Thu Dec 20, 2018 6:11 am
The reason why I didn't comment was that I thought I had made a good point about the colors of meteors in a recent APOD discussion thread. But when I checked my post, the picture I posted had disappeared.
1) Go to their profile (by tapping on their 'user name' at the right of their posts)
2) Tap on "Search user’s posts"
3) Check through recent posts manually... or search for significant word (i.e., 'meteors').
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Thu Dec 20, 2018 6:03 pm
by MarkBour
Ann wrote: ↑Thu Dec 20, 2018 6:11 am
The reason why I didn't comment was that I thought I had made a good point about the colors of meteors in a recent APOD discussion thread. But when I checked my post, the picture I posted had disappeared.
...
Ann
Ulp! Well, thanks for re-posting it, Ann. Some very interesting info about the colors of vaporizing elements, indeed!
Using Art's reference to it, I also went and read that discussion. (Your picture there came up for me some times, and other times the link would not pull up. Perhaps a communication problem with the server hosting it.)
I had missed that discussion completely, because with my habits, I only read about half of the APOD discussions.
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Thu Dec 20, 2018 7:04 pm
by Ann
I just checked the picture I had posted in the other thread. And lo and behold, that other picture (which was not the same one that I posted here) gives conflicting color information compared with the picture I posted here!
The other picture claimed that iron in a meteor leads to yellow trails. The picture I posted here claims that iron causes aqua-colored trails! Instead it is magnesium that supposedly makes aqua-colored trails according to the picture in the other thread, while the picture I posted here claims that magnesium makes yellow-green trails!
Okay. Here is another voice - or the same one as the one we heard in the picture that I posted in the other thread? - that claims that iron makes yellow trails and magnesium makes blue-green ones. I don't know which claim is correct!
Ann
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Thu Dec 20, 2018 7:44 pm
by Chris Peterson
Ann wrote: ↑Thu Dec 20, 2018 7:04 pm
Okay. Here is another voice - or the same one as the one we heard in the picture that I posted in the other thread? - that claims that iron makes yellow trails and magnesium makes blue-green ones. I don't know which claim is correct!
None of them. And all of them. All of these elements produce multiple emission lines which show up nicely in spectra. And even more dominant are the emission lines from gases in the atmosphere. Combine them all and what we see is typically a very desaturated color- white with a yellow cast or white with a green cast being most common. For the most part, the color that you perceive a meteor to be cannot be used to tell you much of anything about its composition. It tells you more about its altitude and speed than anything else. To determine its composition (and that composition will change with time as the volatile elements burn away and the refractory ones remain) you really need to see the spectrum, not the perceived color.
Ann wrote: ↑Thu Dec 20, 2018 7:04 pm
Okay. Here is another voice - or the same one as the one we heard in the picture that I posted in the other thread? - that claims that iron makes yellow trails and magnesium makes blue-green ones. I don't know which claim is correct!
None of them. And all of them. All of these elements produce multiple emission lines which show up nicely in spectra. And even more dominant are the emission lines from gases in the atmosphere. Combine them all and what we see is typically a very desaturated color- white with a yellow cast or white with a green cast being most common. For the most part, the color that you perceive a meteor to be cannot be used to tell you much of anything about its composition. It tells you more about its altitude and speed than anything else. To determine its composition (and that composition will change with time as the volatile elements burn away and the refractory ones remain) you really need to see the spectrum, not the perceived color.
The transition from oxygen atom green emission
to nitrogen molecule red & blue emission at
100 km (the true edge of space) seems rather obvious.
(Unless, of course, a many layered meteor is simply
doing a Salome seven veils strip routine for us.)
https://en.wikipedia.org/wiki/Aurora#Visual_forms_and_colors wrote:
Red: At the highest altitudes, excited atomic oxygen emits at 630 nm (red); low concentration of atoms and lower sensitivity of eyes at this wavelength make this color visible only under more intense solar activity. The low number of oxygen atoms and their gradually diminishing concentration is responsible for the faint appearance of the top parts of the "curtains". Scarlet, crimson, and carmine are the most often-seen hues of red for the auroras.
Green: At lower altitudes, the more frequent collisions suppress the 630-nm (red) mode: rather the 557.7 nm emission (green) dominates. Fairly high concentration of atomic oxygen and higher eye sensitivity in green make green auroras the most common. The excited molecular nitrogen (atomic nitrogen being rare due to high stability of the N2 molecule) plays a role here, as it can transfer energy by collision to an oxygen atom, which then radiates it away at the green wavelength. (Red and green can also mix together to produce pink or yellow hues.) The rapid decrease of concentration of atomic oxygen below about 100 km is responsible for the abrupt-looking end of the lower edges of the curtains. Both the 557.7 and 630.0 nm wavelengths correspond to forbidden transitions of atomic oxygen, slow mechanism that is responsible for the graduality (0.7 s and 107 s respectively) of flaring and fading.
Blue: At yet lower altitudes, atomic oxygen is uncommon, and molecular nitrogen and ionized molecular nitrogen take over in producing visible light emission, radiating at a large number of wavelengths in both red and blue parts of the spectrum, with 428 nm (blue) being dominant. Blue and purple emissions, typically at the lower edges of the "curtains", show up at the highest levels of solar activity. The molecular nitrogen transitions are much faster than the atomic oxygen ones.
Re: APOD: A Rainbow Geminid Meteor (2018 Dec 19)
Posted: Fri Dec 21, 2018 7:39 am
by Ann
neufer wrote: ↑Fri Dec 21, 2018 4:26 am
(Unless, of course, a many layered meteor is simply
doing a Salome seven veils strip routine for us.)[/list]
A many layered meteor is doing a Salome seven veils strip routine for us! I like it! Many meteors are indeed seen changing colors! So they are burning off one layer after another in glorious technicolor, aren't they?
neufer wrote: ↑Fri Dec 21, 2018 4:26 am
(Unless, of course, a many layered meteor is simply
doing a Salome seven veils strip routine for us.)
A many layered meteor is doing a Salome seven veils strip routine for us! I like it! Many meteors are indeed seen changing colors! So they are burning off one layer after another in glorious technicolor, aren't they?
Meteors that change colors in the specific Auroracolorsequence (described above) are more Baloney than Salome.
neufer wrote: ↑Fri Dec 21, 2018 4:26 am
(Unless, of course, a many layered meteor is simply
doing a Salome seven veils strip routine for us.)[/list]
A many layered meteor is doing a Salome seven veils strip routine for us! I like it! Many meteors are indeed seen changing colors! So they are burning off one layer after another in glorious technicolor, aren't they?
Not layers, but indeed, as a meteor descends into the atmosphere, it burns off different materials at different depths. That's because low melting point elements like sodium and magnesium are the first to go, with refractory elements not burning until the meteor is hotter. This effect is very evident in meteor spectroscopy, but is generally subtle or undetectable in most visual observations, where we see a combination of lines as well as light from atmospheric oxygen and nitrogen. (Consider the dominant lines of sodium and magnesium early in a meteor path- a spectroscope will show them as yellow and green, but our eye will see the pair as warm white- often coming out of a green color produced by the forbidden oxygen line stimulated at very high altitudes.)
A Rainbow Geminid Meteor
