APOD: Perseid Fireball and Persistent Train (2018 Aug 17)

[APOD Robot]

Perseid Fireball and Persistent Train

Explanation: Before local midnight on August 12, this brilliant Perseid meteor flashed above the Poloniny Dark Sky Park, Slovakia, planet Earth. Streaking beside the summer Milky Way, its initial color is likely due to the shower meteor's characteristically high speed. Moving at about 60 kilometers per second, Perseid meteors can excite green emission from oxygen atoms while passing through the thin atmosphere at high altitudes. Also characteristic of bright meteors, this Perseid left a lingering visible trail known as a persistent train, wafting in the upper atmosphere. Its development is followed in the inset frames, exposures separated by one minute and shown at the scale of the original image. Compared to the brief flash of the meteor, the wraith-like trail really is persistent. After an hour faint remnants of this one could still be traced, expanding to over 80 degrees on the sky.

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[BDanielMayfield]

A meteor that blew a smoke ring!

As for the "green emission from oxygen atoms while passing through the thin atmosphere at high altitudes" is this mainly in the ozone layer?


Bruce

[Ann]

A meteor that blew a smoke ring!

As for the "green emission from oxygen atoms while passing through the thin atmosphere at high altitudes" is this mainly in the ozone layer?


Bruce

My amateur totally non-scientific and ignorant gut feeling tells me that a part of the little pebble (or grain of sand) is "exploding" and creating chemical reactions that are green when the meteor is at its brightest and most intense.

Those of you who know what you are talking about, what do you say about my little hypothesis?

Ann

[heehaw]

Nice!

[DomeLord]

How do you know it's not our space junk coming home?

[orin stepanek]

Oops; spelling; Andromeda

Click to view full size image 1 or image 2

[Guest]

Hello.
There is an other wonderful video of the phenomenon taken from Poland by Damian Demendecki.
It is here : https://www.facebook.com/damian.demende ... =3&theater
I will be very interesting to use this opportunity for a triangulation work... Best regards

Olivier Las Vergnas

[BDanielMayfield]

Oops; spelling; Andromeda

Click to view full size image 1 or image 2

Yes Orin, that is unmistakably Andromeda, and I can't spell either.

[Chris Peterson]

How do you know it's not our space junk coming home?

Well, from a single time exposure like this you can't ever know for sure. But the odds are very much against it. The shot was made during the Perseids. This meteor points back to the Perseid radiant. The meteor does not break up in the way we usually observe with space junk. Space junk doesn't typically leave persistent trains. And observationally, less than one in a thousand bright meteors is space junk- the two can be distinguished by speed of entry when the event is caught on video, as thousands per day are.

[Chris Peterson]

A meteor that blew a smoke ring!

So it appears. But in reality, what we're seeing is more of a corkscrew, viewed along its central axis.

[Chris Peterson]

My amateur totally non-scientific and ignorant gut feeling tells me that a part of the little pebble (or grain of sand) is "exploding" and creating chemical reactions that are green when the meteor is at its brightest and most intense.

Those of you who know what you are talking about, what do you say about my little hypothesis?

No chemical reactions, as such. Just the emissions of hot elements, some in the atmosphere, some from the meteoroid body. If you observed this with a spectroscope (as has been done) you'd be able to disentangle the atmospheric emissions from those of the meteoroid. You'd also observe that those of the latter change over time, with the more volatile elements burning off early and the refractory ones going last.

[wallyware]

orin stepanek: yes. M31 to be specific.

[clr]

What did the fireball crash into? Did it do any damage?

[NGC3314]

I recalled scanning this paper Experimental Simulation of Meteorite Ablation during Earth Entry using a Plasma Wind Tunnel, from which I learned:

(1) The spectra of meteors combine glowing (sometimes ionized) atmospheric gases, which happen to dominate in the red part the spectrum, and vaporized meteoroid material, which we mostly see in the blue; and

(2) there is such a thing as a plasma wind tunnel that people use. I bet nothing memorable ever happened during commissioning of such devices.

[Chris Peterson]

What did the fireball crash into? Did it do any damage?

It was reduced to dust and a cloud of atoms while still 100 km above the ground.

[SeedsofEarth]

One minute separating each frame of the persistent trail? I watched the video of this, and it seems there is barely one to two seconds of duration. Am I missing something?

[Chris Peterson]

One minute separating each frame of the persistent trail? I watched the video of this, and it seems there is barely one to two seconds of duration. Am I missing something?

The video is a time lapse.

[Boomer12k]

Wow...cool.... smoke ring....gee....smoke rings to planetary nebula...and ring galaxies...merely coincidence???

:---[===] *

[neufer]

What did the fireball crash into? Did it do any damage?

It was reduced to dust and a cloud of atoms while still 100 km above the ground.

• 100 km above the ground would be reasonable for most shooting stars;
  but fireballs should make it a little further down:

1. What is a fireball? What is the difference between a fireball and a bolide?

• A fireball is another term for a very bright meteor, generally brighter than magnitude -4, which is about the same magnitude of the planet Venus in the morning or evening sky. A bolide is a special type of fireball which explodes in a bright terminal flash at its end, often with visible fragmentation.

6. Can a fireball create a sound? Will the sound occur right away, as you watch the fireball, or is their some delay?

• If a very bright fireball, usually greater than magnitude -8, penetrates to the stratosphere, below an altitude of about 50 km, and explodes as a bolide, there is a chance that sonic booms may be heard on the ground below. This is more likely if the bolide occurs at an altitude angle of about 45 degrees or so for the observer, and is less likely if the bolide occurs overhead (although still possible) or near the horizon. Because sound travels quite slowly, at only about 20 km per minute, it will generally be 1.5 to 4 minutes after the visual explosion before any sonic boom can be heard.

7. How bright does a meteor have to be before there is a chance of it reaching the ground as a meteorite?

• Generally speaking, a fireball must be greater than about magnitude -8 to -10 in order to potentially produce a meteorite fall. Two important additional requirements are that (1) the parent meteoroid must be of asteroidal origin, composed of sufficiently sturdy material for the trip through the atmosphere, and (2) the meteoroid must enter the atmosphere as a relatively slow meteor.
  
  Meteoroids of asteroid origin make up only a small percentage (about 5%) of the overall meteoroid population, which is primarily cometary in nature.
  
  Photographic fireball studies have indicated that a fireball must usually still be generating visible light below the 20 km altitude level in order to have a good probability of producing a meteorite fall. Very bright meteors of magnitude -15 or better have been studied which produced no potential meteorites, especially those having a cometary origin.

8. Can a meteorite dropping fireball be observed all the way to impact with the ground?

• No. At some point, usually between 15 to 20 km altitude, the meteoroid remnants will decelerate to the point that the ablation process stops, and visible light is no longer generated. This occurs at a speed of about 2-4 km/sec.
  
  From that point onward, the stones will rapidly decelerate further until they are falling at their terminal velocity, which will generally be somewhere between 0.1 and 0.2 km/sec (200 mph to 400 mph). Moving at these rapid speeds, the meteorite will be essentially invisible during this final “dark flight” portion of their fall.>>

[Chris Peterson]

What did the fireball crash into? Did it do any damage?

It was reduced to dust and a cloud of atoms while still 100 km above the ground.

• 100 km above the ground would be reasonable for most shooting stars;
  but fireballs should make it a little further down:

Most fireballs are asteroidal material. This was not a very bright fireball (mag -8) and was composed of cometary material. It could easily have burned up very high.

This event did occur in an area that is well populated with meteor cameras, so the details of its path are probably known.