APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Comments and questions about the APOD on the main view screen.
User avatar
neufer
Vacationer at Tralfamadore
Posts: 18374
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by neufer » Tue Feb 19, 2013 4:57 am

Chris Peterson wrote:
Ron-Astro Pharmacist wrote:
It’s interesting that we call our protective shell (from the sun’s harmful radiation and other ejected material) “the Earth’s Magnetic Field” Gives one the impression that it could repel or attract a metallic object. We all know that it is a gravitational effect that allows the more massive meteor/meteorite to contact the Earth so it’s somewhat confusing we refer to our protective field as such.
The Earth's magnetic field is only about 0.5% as strong as a typical bar magnet, and falls off with distance. Only a few percent of meteoroids are iron, and even those spend so little time in the Earth's magnetic field that there is insignificant impact on their trajectories. Of course, both DA14 and the Russian meteor body were stony, with little iron content, and therefore even less affected.
I just submitted my first query to whatif@xkcd.com :
The solar wind is a tenuous "superconducting" gas that is easily repelled by the Earth’s magnetic field.

Would it be possible to produce a large enough superconducting metalized Mylar ("Echo") balloon
such that the magnetic repulsion from the Earth would balance out the gravitational attraction
in a low earth stationary equatorial orbit?
Art Neuendorffer

User avatar
Chris Peterson
Abominable Snowman
Posts: 16151
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Chris Peterson » Tue Feb 19, 2013 6:01 am

scottjsw wrote:Thanks Chris, you've answered many of my suppositions. But why would all of the objectsorbiting from the formation of the Moon be gone in a few million years? Aren't the annual meteor showers due to passage through debris strewn regions?
All naturally occurring orbital systems with more than two bodies are ultimately unstable, including the entire Solar System. Within the Solar System are regions of greater or less stability. The planets exist in highly (but not perfectly) stable orbital positions. The asteroids in the belt have distributed themselves into relatively stable zones, and unstable zones have been cleared out. All small bodies with orbits that pass anywhere near the orbits of planets are in relatively unstable orbits, since they will be repeatedly perturbed, with the result that they will either be deflected into the Sun, or ejected from the Solar System completely. So we can generally assume that bodies found orbiting in the inner system are recent additions, perturbed (usually by Jupiter) from some other location, generally the asteroid belt. And after a few million years or less, they will be perturbed into radically different orbits.
Chris

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

User avatar
Chris Peterson
Abominable Snowman
Posts: 16151
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Chris Peterson » Tue Feb 19, 2013 6:12 am

FLPhotoCatcher wrote:Chris, you're incorrectly ascribing bogus statistical rules to scottjsw (and I). You say that the odds that "you will be outside, wearing a swimsuit, and eating a sandwich when a huge fireball passes over" is small, and it is. The earth is like a particular person, not all the people on earth. The same for the car crash analogy.
I don't think so. It is the time of the event that is like a particular person. The odds of any coincidence happening at a specific time is very small, yet every coincidence will happen at a specific time.

Extremely unlikely astronomical coincidences happen every day, including ones much, much more unlikely than a couple of relatively large objects passing so close in space and time. There are billions of possible unlikely events, and billions of years for them to occur. We simply notice certain ones and not others. It's a kind of selection bias.
The odds of a 50 meter (or larger) asteroid coming as close (or closer) to the earth as 2012 DA14 did is not known - I've heard it's once in one hundred years on average. Scientists say it is a "record close approach for a known object of this size."
But this is a misleading way of expressing things. What about a similar object that passes a little farther away? It would still be reported as a rare event. It's like the big deal made a few years back when Mars was particularly close. Closer than it will be for 100 years! Sounds impressive, but it's barely closer than a dozen other apparitions.
The Russian meteor was "the largest object known to have entered the Earth's atmosphere since the 1908 Tunguska event."
I think that's arguable. I have good reason to believe that larger infrasound events have been recorded. But regardless, it doesn't matter. Even if a coincident event like this only happens every 10,000 years, it's happened a half million times in the history of the Solar System. Things that happen with that frequency can be observed every day.
Chris

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

User avatar
MargaritaMc
Look to the Evenstar
Posts: 1836
Joined: Wed Jan 09, 2013 10:14 pm
Location: 28°16'7"N 16°36'20"W

Probability... and astronomical coincidences

Post by MargaritaMc » Tue Feb 19, 2013 12:36 pm

geckzilla wrote:So the two meteors are only related by being in the same solar system with us. Which is about the same as my relationship to President Obama.
What a coincidence! WHAT is the is the probability of Geckzilla and Barack Obama being alive, on the same planet, at the very same time, in the total life span of the Universe? :shock:

I am currently doing some remedial maths, and the study of probability has just been introduced. At a very basic level, I hasten to add, so I am not competent to contribute to this debate. But it has taught me enough to show me that what I sense intuitively about the probability of an occurrence is not necessarily correct.

It occurs to me that an Introduction to Probability would be a useful tool for Forum members (as are Robert Nemiroff's lectures on Introductory Astronomy and on Physics).

I don't know what the formal forum rules would be about putting up something in the Resources section, but if it were permissible, is there anyone able - and willing! - to tackle this? :?:
(Chris...?)

Margarita
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

User avatar
rstevenson
Quis custodiet ipsos custodes?
Posts: 2647
Joined: Fri Mar 28, 2008 1:24 pm
Location: Dartmouth, NS, Canada

Re: Probability... and astronomical coincidences

Post by rstevenson » Tue Feb 19, 2013 1:28 pm

MargaritaMc wrote:It occurs to me that an Introduction to Probability would be a useful tool for Forum members (as are Robert Nemiroff's lectures on Introductory Astronomy and on Physics).
I've often thought that people should be introduced to probability and statistics way back in grade school. But there would be one unintended consequence of a society which understands statistics: lottery sales would take a nose dive. :lol2:

Rob

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18374
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: Probability... and astronomical coincidences

Post by neufer » Tue Feb 19, 2013 1:33 pm

MargaritaMc wrote:
geckzilla wrote:
So the two meteors are only related by being in the same solar system with us.

Which is about the same as my relationship to President Obama.
What a coincidence! WHAT is the is the probability of Geckzilla and Barack Obama being alive,
on the same planet, at the very same time, in the total life span of the Universe? :shock:
Geckzilla & Barack Obama are in a relationship? :shock: (Who knew?)

'How often have I said to you that when you have eliminated the impossible,
whatever remains, however improbable, must be the truth?'
- Sherlock Holmes, The Sign of Four
Art Neuendorffer

Sam
Science Officer
Posts: 156
Joined: Thu Aug 19, 2010 8:39 pm

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Sam » Tue Feb 19, 2013 5:45 pm

I remember this podcast as addressing many of these probability issues: http://www.radiolab.org/2009/jun/15/.
Sam
"No avian society ever develops space travel because it's impossible to focus on calculus when you could be outside flying." -Randall Munroe

User avatar
bystander
Apathetic Retiree
Posts: 20763
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by bystander » Tue Feb 19, 2013 6:47 pm

Russian Fireball Largest Ever Detected by CTBTO’s Infrasound Sensors
CTBTO | 2013 Feb 18

Image
17 infrasound stations in the CTBTO's network detected the infrasonic waves
from the meteor that broke up over Russia's Ural mountains on 15 Feb. 2013.
The furthest station to record the sub-audible sound was 15,000 km away in
Antarctica. (Credit: CTBTO)
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
MargaritaMc
Look to the Evenstar
Posts: 1836
Joined: Wed Jan 09, 2013 10:14 pm
Location: 28°16'7"N 16°36'20"W

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by MargaritaMc » Tue Feb 19, 2013 7:03 pm

Sam wrote:I remember this podcast as addressing many of these probability issues: http://www.radiolab.org/2009/jun/15/.
Sam
That is very interesting podcast and very relevant to this current discussion. Thank you, Sam, for posting it. :clap:

M.
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
— Dr Debra M. Elmegreen, Fellow of the AAAS

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18374
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by neufer » Tue Feb 19, 2013 8:13 pm

MargaritaMc wrote:
Sam wrote:
I remember this podcast as addressing many of these probability issues:
http://www.radiolab.org/2009/jun/15/.
That is very interesting podcast and very relevant to this current discussion. Thank you, Sam, for posting it. :clap:
Click to play embedded YouTube video.
I would be a little more suspicious of any PODcasts on this subject if I were you, Margarita. And you best stay awake :!:
http://en.wikipedia.org/wiki/The_Body_Snatchers wrote:
<<In deep space, a race of gelatinous creatures abandon their dying world. Pushed through the universe by solar wind, they make their way to Earth and land in San Francisco. Some fall on plant leaves, assimilating them and forming small pods with pink flowers. Elizabeth Driscoll, an employee at the San Francisco health department, is one of several people who bring flowers home. The next morning, Elizabeth's partner, Geoffrey Howel, suddenly becomes distant, and she senses that something is wrong. Her colleague, health inspector Matthew Bennell (Donald Sutherland), suggests that she see his friend, psychiatrist Dr. David Kibner (Leonard Nimoy).>>
Your friendly APOD blogger,
Art Neuendorffer

User avatar
MargaritaMc
Look to the Evenstar
Posts: 1836
Joined: Wed Jan 09, 2013 10:14 pm
Location: 28°16'7"N 16°36'20"W

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by MargaritaMc » Tue Feb 19, 2013 9:34 pm

Neufer wroteI would be a little more suspicious of any PODcasts on this subject if I were you, Margarita. And you best stay awake
Toooooo late...

I've been pod-snatched... :derp:
"In those rare moments of total quiet with a dark sky, I again feel the awe that struck me as a child. The feeling is utterly overwhelming as my mind races out across the stars. I feel peaceful and serene."
&mdash; Dr Debra M. Elmegreen, Fellow of the AAAS

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Beyond » Wed Feb 20, 2013 3:19 am

Hold on... aren't we all APODers already :?: :?:
To find the Truth, you must go Beyond.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18374
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by neufer » Wed Feb 20, 2013 4:07 am

Beyond wrote:
Hold on... aren't we all APODers already :?: :?:
There's nothing to be afraid of, Beyond. They were right. It's painless. It's good. Come. Sleep.
Art Neuendorffer

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Beyond » Wed Feb 20, 2013 4:35 am

neufer wrote:
Beyond wrote:
Hold on... aren't we all APODers already :?: :?:
There's nothing to be afraid of, Beyond. They were right. It's painless. It's good. Come. Sleep.
ha-ha, are you kidding :?: When i fall asleep, they're :ohno: of me :!: :yes: :lol2:
To find the Truth, you must go Beyond.

User avatar
neufer
Vacationer at Tralfamadore
Posts: 18374
Joined: Mon Jan 21, 2008 1:57 pm
Location: Alexandria, Virginia

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by neufer » Wed Feb 20, 2013 5:21 pm

Memorable quotes for Invasion of the Body Snatchers (1956)
Wilma Lentz: There's no emotion. None. Just the pretense of it. The words, the gesture, the tone of voice, everything else is the same, but not the feeling.

Dr. Miles J. Bennell: In my practice, I've seen how people have allowed their humanity to drain away. Only it happened slowly instead of all at once. They didn't seem to mind... All of us - a little bit - we harden our hearts, grow callous. Only when we have to fight to stay human do we realize how precious it is to us, how dear.
Last edited by neufer on Wed Feb 20, 2013 11:41 pm, edited 1 time in total.
Art Neuendorffer

retrogalax

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by retrogalax » Wed Feb 20, 2013 7:05 pm

Hello,

Can we say that the meteor "exploded" (because of temperature or pressure) ? Is this that created the sound wave ? The white smoke is water ? From where comes the (stunning) flash of light ? Did you see at 1.10 there is a plume.
Is it rock vaporisation ? Hopefully it went top of our heads.

User avatar
Chris Peterson
Abominable Snowman
Posts: 16151
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Chris Peterson » Wed Feb 20, 2013 7:42 pm

retrogalax wrote:Can we say that the meteor "exploded" (because of temperature or pressure) ? Is this that created the sound wave ? The white smoke is water ? From where comes the (stunning) flash of light ? Did you see at 1.10 there is a plume.
Is it rock vaporisation ? Hopefully it went top of our heads.
"Explosion" is a reasonable term, frequently applied when meteors violently break apart.

A body larger than a few millimeters moving through the atmosphere at a hypersonic speed experiences very large forces on the leading surface created by compressing air in front of it (this is called ram pressure). If those forces create stresses that exceed the material strength of the body, it will break into two or more pieces. The rapid compression of air in front of the body creates heat, which burns or melts away the outer surface, a process called ablation. This is a very efficient way of removing heat, and the body itself undergoes very little change in temperature from whatever it had in space. When that body breaks up, a lot of new surface area is exposed, which immediately begins ablating. This is the primary source of heat and light we experience when a meteor explodes. It also creates the primary shock wave, recorded by instruments and detected audibly if the event is large enough or occurs close enough to the ground. The primary body may generate a conventional supersonic shock wave (sonic boom) on the ground if it survives low enough in the atmosphere (below about 50 km). The individual, typically short-lived bodies produced by an explosion can also generate sonic booms (again, only below about 50 km), resulting in a sound often compared to artillery fire, and quite recognizable in some of the Russian videos immediately after the primary explosion.

The trail itself is primarily dust particles (smoke) from the ablating meteoroid. These trails are usually not pure white. The very white appearance of the smoke trail in the case of the Russian meteor may be indicative of its material properties, but has also been suggested to result from some sort of water condensation, similar to a contrail. The details of the trail structure and color remain under investigation.
Chris

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

User avatar
bystander
Apathetic Retiree
Posts: 20763
Joined: Mon Aug 28, 2006 2:06 pm
Location: Oklahoma

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by bystander » Wed Feb 20, 2013 10:13 pm

What’s the Difference Between a Comet, Asteroid and Meteor?
Universe Today | Nancy Atkinson | 2013 Feb 20

‘Name That Space Rock’ — Credit and copyright: Tim Lillis.
— describes the difference between all those flying rocks from space.
Know the quiet place within your heart and touch the rainbow of possibility; be
alive to the gentle breeze of communication, and please stop being such a jerk.
— Garrison Keillor

User avatar
Beyond
500 Gigaderps
Posts: 6889
Joined: Tue Aug 04, 2009 11:09 am
Location: BEYONDER LAND

Re: APOD: The Great Russian Meteor of 2013 (2013 Feb 18)

Post by Beyond » Fri Feb 22, 2013 4:43 am

Pictures from a professional photographer who just happened to have set up his camera pointing where the Russian meteor exploded in the sky.
http://www.dailymail.co.uk/news/article ... rough.html
To find the Truth, you must go Beyond.

epitalon
Ensign
Posts: 22
Joined: Mon Jan 25, 2010 10:05 am

Re: Coincidence with 2012 DA14

Post by epitalon » Fri Feb 22, 2013 10:50 am

Hello all,

I would like to know something, please:
what are the conditions on velocity, relative to earth, if any, for an asteroid to enter earth atmosphere after half a U-turn around earth.
I mean: could an asteroid have a parabole or an elongated elipse trajectory, relative to earth, and enter earth atmosphere at its perigee ?

I have in mind that the russian meteor could be on a trajectory similar to 2012 DA 14, approach earth from the south of ecliptic plane and still enter earth atmosphere on a line parallel to the ecliptic plane.

Where I could be wrong ?
Why scientists are so certain about that the russian meteor came from another direction than 2012 DA 14....

Thanks in advance

User avatar
Chris Peterson
Abominable Snowman
Posts: 16151
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Coincidence with 2012 DA14

Post by Chris Peterson » Fri Feb 22, 2013 3:15 pm

epitalon wrote:I would like to know something, please:
what are the conditions on velocity, relative to earth, if any, for an asteroid to enter earth atmosphere after half a U-turn around earth.
I mean: could an asteroid have a parabole or an elongated elipse trajectory, relative to earth, and enter earth atmosphere at its perigee ?
This is only possible if the body is in orbit around the Earth in the first place. Otherwise it doesn't have a perigee at all. A body in a solar orbit can't be captured by the Earth except by aerobraking- losing energy after dipping into the atmosphere. Such a meteor can, potentially, touch the atmosphere on one side of the Earth and again on the other, or even go all the way around. It will, however, still have the same inclination it had while in solar orbit.
I have in mind that the russian meteor could be on a trajectory similar to 2012 DA 14, approach earth from the south of ecliptic plane and still enter earth atmosphere on a line parallel to the ecliptic plane.
Not possible. The Russian meteoroid was in solar orbit (a well established orbit, based on the many video observations of the event). That orbit was very different from DA14's orbit. DA14 is in an orbit similar to Earth's. The meteoroid that created the Russian meteor was in an orbit that extended to the asteroid belt, and was on a completely different inclination. There are no plausible mechanisms that could have shifted a piece of DA14 into that different orbit in the hours before the meteor.
Why scientists are so certain about that the russian meteor came from another direction than 2012 DA 14....
Because orbital dynamics is a completely understood science, and both of these bodies were very well observed.
Chris

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

epitalon
Ensign
Posts: 22
Joined: Mon Jan 25, 2010 10:05 am

Re: Coincidence with 2012 DA14

Post by epitalon » Fri Feb 22, 2013 4:17 pm

Chris Peterson wrote:This is only possible if the body is in orbit around the Earth in the first place. Otherwise it doesn't have a perigee at all. A body in a solar orbit can't be captured by the Earth except by aerobraking- losing energy after dipping into the atmosphere. Such a meteor can, potentially, touch the atmosphere on one side of the Earth and again on the other, or even go all the way around. It will, however, still have the same inclination it had while in solar orbit.
Thanks Chris for your kind response.
I understand know that I must not consider only the speed of the small body relative to earth but its total kinetic energy (relative to the sun). Am I right ?

So, if a small body with the same orbit as 2012DA 14 (11 degree of inciination relative to the ecliptic), if slowed down then caught by earth gravitational field, would end up turning around earth in the same plane (with same 11 degree of inciination relative to the ecliptic) ?
I understand that it would not turn around for long, because of the air drag...

User avatar
Chris Peterson
Abominable Snowman
Posts: 16151
Joined: Wed Jan 31, 2007 11:13 pm
Location: Guffey, Colorado, USA

Re: Coincidence with 2012 DA14

Post by Chris Peterson » Fri Feb 22, 2013 4:38 pm

epitalon wrote:Thanks Chris for your kind response.
I understand know that I must not consider only the speed of the small body relative to earth but its total kinetic energy (relative to the sun). Am I right ?
Like many interesting physics problems, it is possible to construct orbital dynamics questions from the perspective of total energy (not just kinetic energy). I think that your intuition here, seeing how energy must be involved in a change of orbital parameters, is solid.
So, if a small body with the same orbit as 2012DA 14 (11 degree of inciination relative to the ecliptic), if slowed down then caught by earth gravitational field, would end up turning around earth in the same plane (with same 11 degree of inciination relative to the ecliptic) ?
Correct. Actually, there's more involved than just the inclination- all of the orbital parameters for the Russian meteoroid were very different from that of DA14. But inclination is probably the easiest to visualize. It requires a lot of energy to change orbital inclination. In fact, the energy that would be necessary to make a sudden change from DA14's inclination to that of the Russian meteoroid would have probably fragmented a body the size and composition of the latter. The change could have occurred over a long period, of course, but in that scenario the two pieces would have drifted very far apart, and their original relationship could no longer explain the coincidence of their near simultaneous arrival at Earth.
I understand that it would not turn around for long, because of the air drag...
It could just be an Earth-grazer, and either remain is solar orbit, or come back to the Earth at some time in the future. But if it touched the atmosphere twice, I think we can safely conclude that the second time will be its end.
Chris

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