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

[Steve Dutch]

The meteor was much brighter than the Sun for a couple of seconds. Also it broke up about 20 kilometers above the ground but is low in the sky in most of the videos, so the slant range is maybe 100 km.

Solar flux = 1370 W/m2, and the Russian bolide was much brighter than the sun – say 10,000 W/m2. If most of the energy was released during peak output (2 sec), the energy flux was 20,000J/m2

Assume a slant range of 100 km. The area of a sphere 100 km in radius = 4pi x 100,000^2 m^2 = 13 x 10^10 m^2

Total output in all directions was 20,000J/m2 x 13 x 10^10m2 = 26 x 10^14 J

1 kt = 4.2 x 10^12J (Defined to be one trillion calories. Fun fact: one gram of TNT contains 1000 cal = 1 food calorie. Snap, crackle and POP!!!)

Output in kT = 26 x 10^14/4.2 x 10^12 = 600 kT. This is a bit higher than published estimates but not at all bad considering the rough and ready guesstimates from the videos.

The energy in the sound and shock waves would be small compared to the heat and light output.

[Chris Peterson]

A

car-sized chunk of ice and rock

pretty-much describes a comet. Incoming at 140,000 mph, 7 meters in diameter, approximately 10,000 metric tons (http://spaceweather.com/), sew! howcome nobody saw it coming? I guess the Air Force Space Surveillance Radar http://spaceweatherradio.com/navspasur.php is primarily interested in forecasting windows of opportunity for rocket launches; all of the non-reserved telescope time on the dark side was watching 2012 DA14 or scanning for Potentially Hazardous Asteroids?

We have no technology for using radar to scan for hazardous objects. All such bodies are detected optically, and this object was so small it might have gone undetected under any circumstances. However, in this case, its position placed it near the Sun, meaning that it was undetectable optically because as it got close it was a daytime object.

[Chris Peterson]

The energy in the sound and shock waves would be small compared to the heat and light output.

Infrasound detectors are generally the most accurate way to assess total energy released, but that data is only available for the largest events. In the vast majority of cases, energy is determined by profiling the light curve from videos- a calculation similar to what you've done. There are standard formulas relating luminosity to mass, but these often require a degree of guesswork, since they depend on characteristics of the parent body that are frequently unknown.

[danstarr]

Here's a link to a video of the crater that was found when the meteor touched down!

http://www.military.com/video/explosion ... 924394001/

[bystander]

Here's a link to a video of the crater that was found when the meteor touched down!

http://www.military.com/video/explosion ... 924394001/

That is not a meteor crater, but a natural gas fire in Derweze, sometimes called the Door to Hell, that has been burning since 1971.

[Steve Dutch]

Chis Peterson wrote: "Infrasound detectors are generally the most accurate way to assess total energy released, but that data is only available for the largest events."

There is a fair amount of infrasound for this event. As I pointed out, this was a back of the envelope calculation, designed to show it's not hard to get a decent yield estimate by simple means.

[Chris Peterson]

There is a fair amount of infrasound for this event. As I pointed out, this was a back of the envelope calculation, designed to show it's not hard to get a decent yield estimate by simple means.

I agree (and I thought that's what I said, but maybe not very well).

[BDanielMayfield]

More like bus-sized than car-sized, and probably all rock, no ice.

I too keyed on the mention of ice in today’s description Chris, but didn’t have enough time to fire off a post until now. I haven’t seen anything written about ice in this object until this description. This object must have had a very large, comet like eccentricity. Isn’t it possible that it wasn’t an asteroid at all, and couldn’t that help to explain why no meteorites have been found yet? And what was it's orbit like before it crashed to earth?

[FLPhotoCatcher]

A

car-sized chunk of ice and rock

pretty-much describes a comet. Incoming at 140,000 mph, 7 meters in diameter, approximately 10,000 metric tons (http://spaceweather.com/), sew! howcome nobody saw it coming? I guess the Air Force Space Surveillance Radar http://spaceweatherradio.com/navspasur.php is primarily interested in forecasting windows of opportunity for rocket launches; all of the non-reserved telescope time on the dark side was watching 2012 DA14 or scanning for Potentially Hazardous Asteroids?

http://topaz.streamguys.tv/~spaceweather/

More like house sized - 17 meters in diameter, or almost 56 feet. According to the latest estimate from NASA, "The asteroid was about 17 meters in diameter and weighed approximately 10,000 metric tons."
The odds of a meteorite the size of the Russian one hitting on the same day as one even larger asteroid passing close to earth, was about 36,500 to 1. Add in the other fireballs visible over various cities, and the odds against it all happening like that by chance were astronomically small.

[Chris Peterson]

The odds of a meteorite the size of the Russian one hitting on the same day as one the size of the larger asteroid that passed close to earth, was about 36,500 to 1. Add in the other fireballs visible over various cities, and the odds against it all happening like that by chance were astronomically small.

The odds weren't all that small. Bodies this size hit the Earth every few years. The once-in-a-century reference is to bodies that deliver so much energy near the ground. Most bodies this size or somewhat larger deposit their energy much higher, and little reaches to the ground. And bodies like DA14 pass quite close to the Earth every few years, as well.

[neufer]

[b][color=#0000FF]In this image, the orbit of the Earth is the green circle. That of asteroid 2012 DA14, which passed by Earth, is the smaller nearly circular blue ellipse that is almost entirely within the orbit of the Earth. The larger elongated blue ellipse, stretching beyond the orbit of Mars, is the orbit of the Russian meteor.[/color][/b]

---

I haven’t seen anything written about ice in this object until this description. This object must have had a very large, comet like eccentricity. Isn’t it possible that it wasn’t an asteroid at all, and couldn’t that help to explain why no meteorites have been found yet? And what was it's orbit like before it crashed to earth?

The aphelion of the Russian meteor was within the asteroid belt
while its perihelion had just approached Venus's orbit
without any indication of a cometary tail
(or of a meteor shower that it might have entailed).

[danstarr]

bystander - Thanx for the correction. I shouldn't have believed the posted video seeing as there was no other information on a crater in the news. Thanx again.

[Chris Peterson]

I haven’t seen anything written about ice in this object until this description. This object must have had a very large, comet like eccentricity. Isn’t it possible that it wasn’t an asteroid at all, and couldn’t that help to explain why no meteorites have been found yet? And what was it's orbit like before it crashed to earth?

The aphelion of the Russian meteor was within the asteroid belt while its perihelion had just approached Venus's orbit without any indication of a cometary tail (or of a meteor shower that it might have entailed).

In addition, meteorites have been found, and appear to be ordinary chondrites, which are associated with asteroids (implying very little water). If the meteorites were carbonaceous chondrites we might be more inclined to suspect a cometary origin (although a comet in this orbit would likely have had most of its volatiles, including water, boiled off long ago).

[FLPhotoCatcher]

The odds of a meteorite the size of the Russian one hitting on the same day as one the size of the larger asteroid that passed close to earth, was about 36,500 to 1. Add in the other fireballs visible over various cities, and the odds against it all happening like that by chance were astronomically small.

The odds weren't all that small. Bodies this size hit the Earth every few years. The once-in-a-century reference is to bodies that deliver so much energy near the ground. Most bodies this size or somewhat larger deposit their energy much higher, and little reaches to the ground. And bodies like DA14 pass quite close to the Earth every few years, as well.

I'm not sure where you get your info, but I think you are wrong.
The numbers are still preliminary, but Paul Chodas of NASA's Near-Earth Object Program Office said, "We would expect an event of this magnitude to occur once every 100 years on average. When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones." So, in fact, the blast would have been even larger if the asteroid had completely burned up. Also according to NASA, "Based on the duration of the event, it was a very shallow entry." and the asteroid "broke apart about 12 to 15 miles (20 to 25 km) above Earth's surface. The energy of the resulting explosion was in the vicinity of 500 kilotons of TNT." I would think if you call its trajectory "very shallow", that would mean that most come in steeper, and if this one did, it would have exploded closer to the ground, and more completely, resulting in a stronger shock wave.
And as for the larger asteroid DA14, it was a record close approach for a known object of this size. I heard that it too was an event expected once every 100 years or so.

[Chris Peterson]

The odds weren't all that small. Bodies this size hit the Earth every few years. The once-in-a-century reference is to bodies that deliver so much energy near the ground. Most bodies this size or somewhat larger deposit their energy much higher, and little reaches to the ground. And bodies like DA14 pass quite close to the Earth every few years, as well.

I'm not sure where you get your info, but I think you are wrong.
The numbers are still preliminary, but Paul Chodas of NASA's Near-Earth Object Program Office said, "We would expect an event of this magnitude to occur once every 100 years on average. When you have a fireball of this size we would expect a large number of meteorites to reach the surface and in this case there were probably some large ones." So, in fact, the blast would have been even larger if the asteroid had completely burned up. Also according to NASA, "Based on the duration of the event, it was a very shallow entry." and the asteroid "broke apart about 12 to 15 miles (20 to 25 km) above Earth's surface. The energy of the resulting explosion was in the vicinity of 500 kilotons of TNT." I would think if you call its trajectory "very shallow", that would mean that most come in steeper, and if this one did, it would have exploded closer to the ground, and more completely, resulting in a stronger shock wave.

"An event like this" refers to one that delivers so much energy close to the ground, not to a collision with a body of this size. 500 kt scale events have been detected in the past by infrasound arrays. In terms of damage, the strength of the blast is determined not by how much of the body burns up, but by how rapidly it does so. Had there been no disruption, the entire mass would have burned over 30 seconds. The same total energy would have been delivered, but it would have caused no damage.

Meteorites are typically only seen with parent bodies that are slow and shallow in their entry. Bodies that are fast, or enter at a steep angle, burn up completely while still quite high. A shallow angle allows more time for the body to slow down, and it therefore experiences less stress. (This object fragmented at a height of 27 km.)

[Ron-Astro Pharmacist]

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.

I guess I’m struggling with the idea that a bar magnet can deflect an object fairly equal to its size but our Earth can’t for an object much, much smaller. It has to be much to the nth smaller. Obviously the Earth isn’t a giant, strong magnet but I’ve always felt it had a pretty strong magnetic field.

And I guess it would be too wordy to call it “the Earth’s diffuse magnetic field”; even if that would be a better term. Anyone have a feel for how much matter is actually deflected as long as it isn't one big chunk? A DA14 or a Great Russian amount - so to say. It obviously protects us from some amount of “spread out” matter.

[Chris Peterson]

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.

I guess I’m struggling with the idea that a bar magnet can deflect an object fairly equal to its size but our Earth can’t for an object much, much smaller. It has to be much to the nth smaller. Obviously the Earth isn’t a giant, strong magnet but I’ve always felt it had a pretty strong magnetic field.

And I guess it would be too wordy to call it “the Earth’s diffuse magnetic field”; even if that would be a better term. Anyone have a feel for how much matter is actually deflected as long as it isn't one big chunk? A DA14 or a Great Russian amount - so to say. It obviously protects us from some amount of “spread out” matter. :?: :D

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.

[scottjsw]

I still believe the odds against this too great to ascribe it to coincidence alone. Objects the siaze of the asteroid come close once every hunder years or so, and objects the size of the Russian meteor once in 10 years. To have these two events on the same day? I think there must be some explanation.

What about a common origin, something that created a huge amount of debris blasting out from a point on Earth's orbit in all directions, some of which may well have entered stable orbits, all of them intersecting Earth's orbit at that point of origin. Well, the origin of the Moon when Theia crashed into Earth could be such a common point of origin. Perhaps there are many objects around the size of the two we encountered on Feb 15th, and they all intersect our orbit at about that place relative to the Sun. There was a large meteoite on Feb 12th, 1947, and then these two. There are predictions based on this hypothesis that are testable: if there are rocky bits of the meteor, they ought to have isotopic concordance, as do Moon and Earth rocks.

There would have been rocky and iron debris pieces (see the video simulations of the Moon's origin). The 1947 meteroid is iron. Particles of the Russian Meteor are also supposed to be iron. Perhaps there are properties of the iron that will show similarities?

The different trajectories of the two objects still intersected with Earth's orbit. I think my hypothesis may fit these observations.

Of course, this means Valentine's Day has new meaning. I think we ought to look closely as we approach this spot next year.

[owlice]

A friend from Lebanon and I were visiting NYC; we were walking down Fifth Avenue in NYC and bumped into his college roommate, who he hadn't seen in some years and who was visiting NYC for a week and leaving the next day. What are the odds that we'd all be walking in opposite directions on the same sidewalk in such a populated city that none of us lived in at the same time?! Not very high! Yet it still happened!

It was a coincidence. They happen.

And Valentine's Day still means exactly what it did before: half-priced chocolate on February 15.

ETA: composition of this meteor is not iron, so far as I have read; see here, for example.

[Chris Peterson]

I still believe the odds against this too great to ascribe it to coincidence alone. Objects the siaze of the asteroid come close once every hunder years or so, and objects the size of the Russian meteor once in 10 years. To have these two events on the same day? I think there must be some explanation.

Actually, objects the size of DA14 come around every few years, and so do objects the size of the Russian meteor.

By the statistical rules you are using, just about everything is unlikely beyond belief. What are the odds that you will be outside, wearing a swimsuit, and eating a sandwich when a huge fireball passes over? Pretty small, no? Yet it is very likely that at least one person will be doing just this every time a widely witnessed fireball occurs (several times a year). What are the odds that any two random cars will collide with each other? Millions to one? Yet unrelated pairs of cars collide all the time. Every coincidence becomes seemingly impossible when analyzed that way.

What about a common origin, something that created a huge amount of debris blasting out from a point on Earth's orbit in all directions, some of which may well have entered stable orbits, all of them intersecting Earth's orbit at that point of origin.

DA14 is not in a very stable orbit. Inner system asteroids tend to get perturbed rather quickly. I doubt it's been anywhere near its present orbit since the last time a large enough impact occurred on Earth to send debris into space. The Russian meteoroid is in an absolutely typical orbit for a body originating in the asteroid belt. Similar orbits have been calculated for many bright fireballs. There's absolutely no reason to think the two are related. And even if they were, it would take a long time, and many additional perturbations, for their orbits to become so different. Consider that the two bodies have different orbital periods: it is as unlikely that any related components would come together again at the same place and time as for any unrelated bodies.

Well, the origin of the Moon when Theia crashed into Earth could be such a common point of origin.

No debris from that event remains in the inner system, as that environment does not allow for small bodies to have stable orbits longer than a few million years.

There was a large meteoite on Feb 12th, 1947, and then these two. There are predictions based on this hypothesis that are testable: if there are rocky bits of the meteor, they ought to have isotopic concordance, as do Moon and Earth rocks.

The meteor of 1947 produced iron meteorites of a known type. The Russian event produced chondrites, which proves they are not of Earth origin (and that they are unrelated to the 1924 Sikhote-Alin meteorites). We don't have a sample of DA14, of course, but its spectral type (L) matches that of main belt asteroids, so there is every reason to believe it originated there, and was perturbed into its Apollo orbit (which is now an Aten orbit).

[geckzilla]

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.

[scottjsw]

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? And are the orbits of these recent objects so near the orbital plane of the planets? I see the diagram showing them so within the comments on this post. But I also thought they were said to be traveling north to south and south to north. What prevents there being many objects having orbits of very different, even perpendicular planes?
Again, thanks. I'm just a guy reading a bit and thinking about it, and recognize you're applying real knowledge and scholarship to this. I look forward to your further explanations.

[FLPhotoCatcher]

I still believe the odds against this too great to ascribe it to coincidence alone. Objects the siaze of the asteroid come close once every hunder years or so, and objects the size of the Russian meteor once in 10 years. To have these two events on the same day? I think there must be some explanation.

Actually, objects the size of DA14 come around every few years, and so do objects the size of the Russian meteor.

By the statistical rules you are using, just about everything is unlikely beyond belief. What are the odds that you will be outside, wearing a swimsuit, and eating a sandwich when a huge fireball passes over? Pretty small, no? Yet it is very likely that at least one person will be doing just this every time a widely witnessed fireball occurs (several times a year). What are the odds that any two random cars will collide with each other? Millions to one? Yet unrelated pairs of cars collide all the time. Every coincidence becomes seemingly impossible when analyzed that way.

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. A good analogy would be to call the earth a particular truck, and the asteroid that crashed into it, a motorcycle that crashes into the truck, and the near miss asteroid, a car that takes off the truck's mirror. How likely is that to happen in any 24 hour period for that truck?

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." The Russian meteor was "the largest object known to have entered the Earth's atmosphere since the 1908 Tunguska event." And "Infrasonic waves from the meteor that broke up over Russia’s Ural mountains last week were the largest ever recorded by the CTBTO’s International Monitoring System." Both events were rare in a human lifetime. Even if they happen once every 15 years on average, that's still something that should happen only once in every 82,170 years on average.

[geckzilla]

But you're trying to say that simply because they happened within hours of one another that they must be related. That's not logical because their orbits are so different and all it takes is one contradictory fact to call it a coincidence and that fact is right there. Don't your odds work against you if you suppose that at some point the two pieces broke apart in the past and then converged at Earth? That's the only way the orbits could be so different.

[BDanielMayfield]

Art and Chris, thanks for your persuasive answers. This object very likely was asteriodal in nature. FLPhotoCatcher, I’m not questioning your math, but even if the 1 per 82,170 year rate is correct, there would still have been about 12,170 days like last Friday in the last billion years. Stuff happens. I consider myself fortunate to have witnessed it safely.