On Fri, Feb 15, 2013 at 2:22 PM, James Bowery <[email protected]> wrote:
> Obvious question:
> Was the vector correlated with that of the earth approaching asteroid?
No, they were almost perpendicular. Pure and delightful coincidence.
That was my first thought.
< http://www.washingtonpost.com/world/europe/meteorite-injures-more-than-900-in- russian-city/2013/02/15/ff67c624-7770-11e2-aa12-e6cf1d31106b_story.html?wprss=r ss_europe>
Sergei Zakharov, regional branch chairman of the Russian Geographic Society, told the Interfax news agency that three explosions occurred as the meteor blew apart. Judging by my observations, the fireball was flying from southeast to northwest, he said. A bright flare of more than 2,500 degrees [Celsius] happened before the three explosions. The first explosion was the strongest. - - - - - My quick take (partly copied from elsewhere) Consider a small object (in this case the meteor) orbiting a large object (asteroid), as seen from above the orbit. If the orbital velocity of the meteor round the asteroid is small, then the trajectory of the meteor will look like a sine wave around the trajectory of the asteroid. (Similarly, the trajectory of the moon looks like a sine wave superimposed on the orbit of the earth). In this case the trajectory of the meteor will be substantially the same as the asteroid, so it cannot possibly hit the northern hemisphere of Earth. If the orbital velocity of the meteor were very large compared to the asteroid's trajectory then it would trace a cycloid, and COULD hit the earth north-to-south. But orbital velocities of the meteor round the asteroid are most likely to be in the first category. - - - - Then the "southeast to northwest" trajectory made me think it was feasible again. But unless it had a "cycloidal" path it couldn't have grazed the atmosphere in the Northern hemisphere. A lead-time of 16 hours, and an offset of 17,000 miles would make it very unlikely. I'm sure somebody will come up with an orbital calculation/simulation -- I don't have time to try it today.
