[meteorite-list] 2012 DA14 and the Russian meteor: no link

From: Rob Matson <mojave_meteorites_at_meteoritecentral.com>
Date: Sat, 16 Feb 2013 16:32:18 -0800
Message-ID: <000f01ce0ca6$3dd75630$b9860290$_at_cox.net>

Hi Marco,

I couldn't have explained it any better myself. But I have a feeling that
it's the Porthcawl "bolide" (err SST) all over again. Even almost a decade
after that non-event, there are people who like to show that image as
an example of a brilliant fireball. --Rob

-----Original Message-----
From: meteorite-list-bounces at meteoritecentral.com
[mailto:meteorite-list-bounces at meteoritecentral.com] On Behalf Of Marco
Langbroek
Sent: Saturday, February 16, 2013 4:08 PM
To: meteorite-list at meteoritecentral.com
Subject: [meteorite-list] 2012 DA14 and the Russian meteor: no link


Hi all,

I still see suggestions popping up on this list about a possible link between
2012 DA14 and the Russian meteor.

I want to point out that even without an accurate trajectory for the Russian
bolide, a link with 2012 DA14 can be 100% rejected. The orbital geometry of 2012

DA14 and the latitude of 55 N for the Russian bolide make this impossible.

2012 DA14 and any fragments in a swarm in similar orbit, would approach the
earth from deep south. The geocentric radiant for the orbit of 2012 DA14 is at
declination -81 degrees. This means 2012 DA14 fragments approach earth almost
parallel to the earth polar axis, coming from the south. I.e. they approach
towards the south pole and the southern hemisphere.

This means fragments can impact on the southern hemisphere, but not on the
northern hemisphere (except very low latitudes north if we take earth
gravitational curvature of the final trajectory in account). Because the
northern hemisphere, and certainly a place as far north as 55 N, is at the "far
side" of the earth globe as seen from the 2012 DA14 entry direction.

Compare it with a car. A bird coming in frontal will always hit the front of the

car - it cannot hit the back of the car. Chelyabinsk at 55 North latitude is
"the back of the car" in this comparison, given the approach direction of 2012
DA 14 and any fragments of it.

- Marco

----
Dr Marco (asteroid 183294) Langbroek
asteroids at langbroek.org
http://www.marcolangbroek.nl
http://asteroids.marcolangbroek.nl
-----
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Received on Sat 16 Feb 2013 07:32:18 PM PST