APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Comments and questions about the APOD on the main view screen.
User avatar
APOD Robot
Otto Posterman
Posts: 2966
Joined: Fri Dec 04, 2009 3:27 am

APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby APOD Robot » Sun Aug 06, 2017 4:06 am

[img]https://apod.nasa.gov/apod/calendar/S_170806.jpg[/img] Milky Way and Exploding Meteor

Explanation: Next weekend the Perseid Meteor Shower reaches its maximum. Grains of icy rock will streak across the sky as they evaporate during entry into Earth's atmosphere. These grains were shed from Comet Swift-Tuttle. The Perseids result from the annual crossing of the Earth through Comet Swift-Tuttle's orbit, and are typically the most active meteor shower of the year. Although it is hard to predict the level of activity in any meteor shower, in a clear dark sky an observer might see a meteor a minute. This year's Perseids peak nearly a week after full Moon, and so some faint meteors will be lost to the lunar skyglow. Meteor showers in general are best be seen from a relaxing position, away from lights. Featured here is a meteor caught exploding during the 2015 Perseids above Austria next to the central band of our Milky Way Galaxy.

<< Previous APOD This Day in APOD Next APOD >>

User avatar
Chris Peterson
Abominable Snowman
Posts: 13189
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby Chris Peterson » Sun Aug 06, 2017 4:27 am

This is actually less dramatic than it appears. The meteor isn't so much "exploding" as it is disintegrating. The parent body (probably less than a centimeter in diameter) reached deep enough into the atmosphere (50-100 km high) that the aerodynamic pressure on it exceeded the material strength of the stone. It broke apart, exposing a lot more surface area, which resulted in the bright flare and rapid loss of most mass as dust. The heat also ionized both meteoritic gas and atmospheric gas. This left a small cloud which was subsequently spread by high altitude winds and remained visible for several minutes as it dissipated. The motion of the cloud is unrelated to any "explosion" of the meteoroid itself.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

keesscherer
Asternaut
Posts: 3
Joined: Sat Aug 05, 2017 9:50 am

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby keesscherer » Sun Aug 06, 2017 6:41 am

It is the same picture as the 12 aug 2015 APOD: https://apod.nasa.gov/apod/ap150812.html
I was not aware that APOD used the same image more than once. It is an awesome image though!

heehaw

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby heehaw » Sun Aug 06, 2017 10:11 am

Wow! Best meteor picture(s) I have EVER seen!

User avatar
neufer
Vacationer at Tralfamadore
Posts: 14284
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby neufer » Sun Aug 06, 2017 11:22 am

Chris Peterson wrote:
This is actually less dramatic than it appears. The meteor isn't so much "exploding" as it is disintegrating. The parent body (probably less than a centimeter in diameter) reached deep enough into the atmosphere (50-100 km high) that the aerodynamic pressure on it exceeded the material strength of the stone. It broke apart, exposing a lot more surface area, which resulted in the bright flare and rapid loss of most mass as dust. The heat also ionized both meteoritic gas and atmospheric gas. This left a small cloud which was subsequently spread by high altitude winds and remained visible for several minutes as it dissipated. The motion of the cloud is unrelated to any "explosion" of the meteoroid itself.

So it was either a "meteor" or "meteoroid" when it "exploded" and the small cloud is a "meteorite" :?:
Art Neuendorffer

User avatar
rstevenson
Quis custodiet ipsos custodes?
Posts: 2427
Joined: Fri Mar 28, 2008 1:24 pm
Location: Dartmouth, NS, Canada

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby rstevenson » Sun Aug 06, 2017 12:57 pm

keesscherer wrote:It is the same picture as the 12 aug 2015 APOD: https://apod.nasa.gov/apod/ap150812.html
I was not aware that APOD used the same image more than once. It is an awesome image though!

The Sunday APOD image is almost always a repeat; it has been so for many years.

Rob

User avatar
Chris Peterson
Abominable Snowman
Posts: 13189
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby Chris Peterson » Sun Aug 06, 2017 1:43 pm

neufer wrote:
Chris Peterson wrote:
This is actually less dramatic than it appears. The meteor isn't so much "exploding" as it is disintegrating. The parent body (probably less than a centimeter in diameter) reached deep enough into the atmosphere (50-100 km high) that the aerodynamic pressure on it exceeded the material strength of the stone. It broke apart, exposing a lot more surface area, which resulted in the bright flare and rapid loss of most mass as dust. The heat also ionized both meteoritic gas and atmospheric gas. This left a small cloud which was subsequently spread by high altitude winds and remained visible for several minutes as it dissipated. The motion of the cloud is unrelated to any "explosion" of the meteoroid itself.

So it was either a "meteor" or "meteoroid" when it "exploded" and the small cloud is a "meteorite" :?:

During the luminous phase "meteor" usually includes both the parent meteoroid and the secondary phenomena of energy release. Technically, the body itself remains a "meteoroid". The dust particles in the cloud are, indeed, "meteorites" ("any solid object which survived the meteor phase in planetary atmosphere without being completely vaporized"), and are more specifically "meteoritic smoke particles" ("solid object which recondensed in planetary atmosphere from material vaporized during the meteor phase"). Other acceptable terms called out in the definition are "meteoritic dust" and "micrometeorite".
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

FLPhotoCatcher
Science Officer
Posts: 130
Joined: Wed Jul 18, 2012 6:51 am

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby FLPhotoCatcher » Sun Aug 06, 2017 10:16 pm

If you look closely, you will see that the two meteor streaks in the first two frames do not line up. Are one of them added for effect, or is it a piece of the meteor that changed direction when the meteor broke up?
Also, the orangeish stuff (plasma?) around the streak in the first frame had to have propagated from the meteor faster than the speed of sound (based on the idea that the camera's shutter closed before the 2nd frame starts, and the location of the streak in the 2nd frame). Does anyone know what the orange glow is, if not just the normal ionized gas that meteors make?

User avatar
Chris Peterson
Abominable Snowman
Posts: 13189
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby Chris Peterson » Sun Aug 06, 2017 10:29 pm

FLPhotoCatcher wrote:If you look closely, you will see that the two meteor streaks in the first two frames do not line up. Are one of them added for effect?

Almost certainly, the meteor in the second frame is a completely different one.

Also, the orangeish stuff (plasma?) around the streak in the first frame had to have propagated from the meteor faster than the speed of sound (based on the idea that the camera's shutter closed before the 2nd frame starts, and the location of the streak in the 2nd frame).

No, the cloud dissipated slowly. These are long exposures- I'd guess perhaps 30 seconds each.

Does anyone know what the orange glow is, if not just the normal ionized gas that meteors make?

It's a photochemical process that primarily involves sodium, and also iron if it's present in the meteoroid. Both elements react with upper atmpospheric ozone to produce a sustained release of light- 589 nm for sodium, and a range of lines between red and green for iron.
Chris

*****************************************
Chris L Peterson
Cloudbait Observatory
http://www.cloudbait.com

avdhoeven
Science Officer
Posts: 183
Joined: Mon Jul 04, 2011 8:08 pm

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby avdhoeven » Tue Aug 08, 2017 2:11 am

Before people start to dissect the images and saying it's faked I want to make clear these are all original as I shot them. The answers are quite simple.

1) the exposure times were three minutes, so the total time was about 9 minutes, so it was not that fast in motion

2) the stripe in the second image has nothing to do with the meteor. It was a satellite passage if I remember correctly. I think in that time I even looked it up, but don't remember exactly.

Knight of Clear Skies
Ensign
Posts: 18
Joined: Mon Jul 25, 2016 9:02 am

Re: APOD: Milky Way and Exploding Meteor (2017 Aug 06)

Postby Knight of Clear Skies » Wed Aug 09, 2017 12:16 pm

Chris Peterson wrote:No, the cloud dissipated slowly. These are long exposures- I'd guess perhaps 30 seconds each.


The exposures were 180 seconds each and there are four frames, 12 minutes in total. There are some more details in this thread. I suggested submitting it to APOD but if I hadn't I'm sure someone else would have, it's a great capture.

There is another version here which includes the meteor in a wider mosaic.


Return to “The Bridge: Discuss an Astronomy Picture of the Day”

Who is online

Users browsing this forum: Ahrefs [Bot], Case, CommonCrawl [Bot], DotNetDotCom.org [Bot], Majestic-12 [Bot], Yahoo [Bot] and 3 guests