A meteor's lingering tale

By Phil Plait | October 2, 2011 11:44 am

Randy Halverson is a photographer who makes stunning time lapse videos of the night sky (like Tempest Milky Way and Plains Milky Way; seriously, if you haven’t seen those, go watch them now). He’s currently in the process of making a new video, and in one of the frames he happened to catch a bright meteor, a bit of cosmic fluff burning up as it rammed through our atmosphere. What’s neat about this particular incident is that the meteor left behind a glowing streak that lasted for over half an hour!

You can see it there, the red twisty worm at the upper left, across the glow of the Milky Way [click to enbolidenate.]

Technically, that’s called a persistent train, and it’s not actually smoke. As a meteoroid (the actual solid chunk of material) blasts through the air, it ionizes the gases, stripping electrons from their parent atoms. As the electrons slowly recombine with the atoms, they emit light — this is how neon signs glow, as well as giant star-forming nebulae in space. The upper-level winds blowing that high (upwards of 100 km/60 miles) create the twisting, fantastic shapes in the train. The actual details of how this works in meteor trains are not well understood, mainly because they are so difficult to spot and study. It’s hard to point a telescope at a position in the sky when you don’t know where or when a meteor will pass through!

Here’s the frame of the time lapse Randy took that shows the meteor as it burned up (again, click to embiggen). Note that in the hi-res shot you can already see the train; that formed after the meteor was gone, but in this time exposure you can see both simultaneously.

I’ll note it’s not really friction that causes a meteor to burn up. Most of the heating is due to the meteoroid’s hypersonic passage through air, which compresses the gas, heating it up violently. The heat melts the rock (or metal) in the meteoroid, which then blows off, leaving behind a train that fades rapidly. But the glow from the ionized gas takes much longer to decay, leaving the persistent train.

Very cool, and very pretty. I can’t wait to see the video when Randy’s done with it!

Image credit: Randy Halverson, from his site DakotaLapse, used with permission. You can follow Randy on Google+ as well.


Related posts:

Another jaw-dropping time lapse video: Tempest
Gorgeous Milky Way time lapse
The fiery descent of Atlantis… seen from space!
Meteor propter hoc

Comments (32)

  1. This is an awesome catch. I love Randy’s work!

  2. Chris

    For some reason this reminded me of superman’s arrival on Earth
    http://www.youtube.com/watch?v=D7SvTmRllmk
    at least robot chicken’s interpretation of it.

  3. 1/2 hour? OMFFSM, I once, and only once watched a meteor that lasted for around a minute, it was wonderful, a thin line of light drawn in the 1/4 of the sky. Other than that, only average ones, cool but so fast and short-living…

  4. cardoso, the meteor didn’t last a half hour, the persistent train did. The meteor was only in 1 frame of the 30 second exposures of the timelapse.

  5. Maybe someone can explain the difference between the compression of gas heating up the meteorite and friction. Phil very clearly states that it’s not friction but compression – I’m just not seeing a huge amount of difference about the two in this case. Maybe it requires splitting hairs (which is fine) – just hoping for a little definition. Thanks.

  6. Chris

    @5 Bill
    http://www.youtube.com/watch?v=4qe1Ueifekg
    This is an adiabatic process (heat exchange is zero)
    http://en.wikipedia.org/wiki/Adiabatic_process
    And when something is compressed like that it can get very very hot.

  7. Wzrd1

    I’m curious though, if it’s ionized air, why is it a red hue, when air ionizes blue? That train would be more along the lines of ionized hydrogen, if the color rendition is true.

    But, thanks, Phil. Never saw a persistent train before, out of quite a few meteor trains over the years.
    I DID see a nice green fireball once, heading west to east and breaking up over New Jersey. From the rapid motion, it had to have made it into fairly dense air to cross the sky so quickly.

  8. Cometkazie

    Where were the photos taken? I can’t id the vegetation.

    Heating upon compression is what make diesel engines run.

    Friction results from physical. Think of the photos of jets breaking the sound barrier. That’s compression.

  9. Question – is a persistent train indicative of the size of the meteor, or is it more indicative of its composition? Or some other factor?

  10. Vision Engineer

    I wonder how visually persistent the trail really was. A 30 second exposure is bound to show things that are too dim to the unaided eye.

  11. Arthur Maruyama

    @9 Cometkazie:

    From the maker’s website dakotalapse.com it appears that most of his pictures are from the states surrounding and in South Dakota. Among the tags he put onto these particular pictures it appears that he was in South Dakota and that the trees are cottonwood trees.

    @12 Vision Engineer:

    I saw a persistent trail from a Leonid several years ago while in the Lake Mead Recreational Area to which I drove during a visit to Las Vegas. The trail was visible for over two minutes before the winds at altitude dispersed it although I suspect that much of its visibility was due to the city glow from Vegas. Perhaps the trail in these pictures was visible for so long because of the Moon which is washing out the sky at the bottom of the frame in combination with winds which coincidentally did not disperse the trail as quickly as mine.

  12. reidh

    Every day how many tons of Toxic waste drops from space and is burnt in our atmosphere? Don’t tell me, let me guess. You don’t know! And what is that crop? again.

  13. I saw one of these meteor trails once in New Mexico. The meteor also exploded, making an odd ‘POP’ sound.

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