Friday, 15 February 2013

Are 2012 DA14 and the Chelyabinsk meteor related?

This morning, there was a spectacular meteor event over the city of Chelyabinsk, unfortunately resulting in damage and injuries. Of course, with the increasing attention around the asteroid 2012 DA14, this event has immediately sparked the question if the two are related.

They are not.

The reason that we can discount the possibility of the two being associated in any way can be reduced to the following reasons.

Firstly, we need to look at the trajectories. The asteroid 2012 DA14 is approaching from the south. It will slingshot past the Earth and continue rising to the North.

However, the Chelyabinsk event is coming from a different direction. The city is at 55°09′N 61°23′E and the event radiant (the position of origin of the meteor) is above and to the left of the rising sun.


Early appearance of the meteor.

General trajectory.


This puts the meteor origin/radiant at approx. RA 22h and Dec +10.

UPDATE at 10:25 GMT: Revised estimate is now approx, RA 22h Dec +20°

UPDATE: Improved radiant estimate.


Piecing this together is difficult, as video footage does not always come with an associated position. Angle and direction needs to be calibrated from nearby objects (buildings, people, etc.) and using these are ways of estimating scale. Also, we do not always know the location of the observer, which introduces additional uncertainty. Fortunately, as more footage is being posted, we are getting a better estimate of the origin of this meteor.

However, even with the uncertainty, this is still in a COMPLETELY different direction.

Also, we can consider the timing of the events. The closest approach of 2012 DA14 will occur at approximately 19:24 UTC. The Chelyabinsk event occurred at about 9:20 am local time... which is 03:20 UTC. (UTC is Coordinated Universal Time, and provides a common time-zone to allow the comparison.)

If we consider the difference, it is approximately 18 hours. The asteroid is travelling at approximately 8 km/s and, if the Chelyabinsk object was related, it would have required a deep space velocity of about the same. Even if the two were related, this would put the two objects some half a million km apart.


In any case, the two events are not related.

This is just a VERY unusual coincidence.

7 comments:

  1. Not sure I agree... It is true that from the frame of reference of the Earth, the two objects came from different directions. However, remember that the Earth is moving through space.

    It looks like the Chelyabinsk meteor came from the East with a slight Southerly component. So seen from above, it would have been heading to left and down as it passed over the city. The sun was coming up at the time, so Chelyabinsk was swinging into the morning terminator at the time. If the object was in a usual solar orbit (going round in the same direction as the Earth and other planets), then the Earth has run into it (basically, we "rear-ended" it).

    Now, DA14 is coming in from "behind" us - it will pass from the South and rising. That puts it roughly on the same orbital plane as the meteor, but going faster.

    Putting it all together, we had the meteor ambling along slowly, Earth coming up fast behind it and DA14 whizzing along behind Earth.

    The meteor and DA14 may have been spinning around, lapping each other for centuries until Earth rolled in between them yesterday. There may even be a whole ring of small objects associated with DA14, strung out along its orbit. We might hit one of them as well!

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  2. Oh Oscar, that does sound exciting! What an interesting Friday this will be.

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  3. Hi Oscar,
    this is the crossing, where the footage was taken:
    http://maps.yandex.ru/?text=челябинск%2C%20улица%20Бейвеля&sll=61.38710299999997%2C55.1521609999945&sspn=1.290894%2C0.408941&ll=61.299080%2C55.219896&spn=0.080681%2C0.025515&z=14&l=sat

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  4. This is a zoomed view: http://maps.yandex.ru/?text=челябинск%2C%20улица%20Бейвеля&sll=61.38710299999997%2C55.1521609999945&sspn=1.290894%2C0.408941&ll=61.297534%2C55.220508&spn=0.020170%2C0.006379&z=16&l=sat%2Cskl
    and this is a footage http://www.youtube.com/watch?v=4ZxXYscmgRg&feature=player_embedded

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  5. If it helps, others are now starting to put out some pretty graphics to explain our results. And these are now being circulated in the press. For example: http://s.telegraph.co.uk/graphics/html/Years/2013/February/images/Meteor5.png

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  6. Stefan Geens used the moving shadows in a video of the city square to estimate the path of the meteor. It lines up with Lake Chebarkul:

    http://ogleearth.com/2013/02/reconstructing-the-chelyabinsk-meteors-path-with-google-earth-youtube-and-high-school-math/

    This Wikipedia article is now the top Wikipedia news item:

    http://en.wikipedia.org/wiki/2013_Russian_meteor_event

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  7. Thanks for the informative post. What I was wondering about is whether the calculated trajectory for the Russian meteor was including the effects of Earth's gravity. I'm inclined to think it should not be included. To give the best view of what the true orbit of the meteor was, you should give it as if the Earth was not there to interrupt it and change its trajectory with its gravity.
    On the other hand I was able to show using a Hohmann orbit calculator that using the delta-V you get from a close in Earth encounter, up to 11.2 km/s, can change a 2012 DA14 type orbit into the one claimed for the Russian meteor, with one big caveat. The Hohmann calculator assumes you get the delta-V boost all at once. So it's not precisely correct to apply it to a case when you get it from a gravitating body where it's applied over time.
    Here's the calculator:

    Simple Hohmann Transfer Orbit Calculator.
    http://web.archive.org/web/20100128043604/http://home.att.net/~ntdoug/smplhmn.html

    Select the orbit around the Sun and input a little less than 1 AU, say, 135,000,000 km, for the beginning orbit radius, which is that of 2012 DA14, and 2.5 AU, about 375,000,000 for the ending orbit radius, the aphelion for the Russian meteor. You'll see the delta-v needed to change the smaller orbit into an elliptical one with the larger, ending radius as its aphelion is well within that which can be delivered by the Earth's gravity. (Hohmann orbit changes use two delta-v burns. The first changes the original smaller, circular orbit into a larger elliptical one. The second circularizes this into one with that larger radius. For this application we only need it to have the elliptical shape of the Russian meteor's orbit so that first delta-v of the calculator is the only one I'm using.)

    Bob Clark

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