Visitors — December 2012

Two asteroids will pass through the neighborhood of Earth in the next several days. The smallest, 2009 BS5, at 15 meters, will close in at 8.4 Lunar Distance (8.4 x the average distance from Earth to Moon) on December 11. The next day, the larger 4179 Toutatis (a 2.7 kilometer rock), will pass at 18 Lunar Distance. Neither asteroid will be visible to the naked eye, but Toutatis should have a magnitude of 10.7 and be visible through high-end binoculars.

Toutatis is a peanut-shaped asteroid with a cockeyed spin. It’s orbit is well known. The rock passed within 4 Lunar Distance in 2004, and will pass within 7.7 Lunar Distance in 2069.

On December 13, Toutatis will become the 15th asteroid visited by an Earth spacecraft. The Chang’e 2 unmanned Chinese spacecraft, which first visited the Moon, then the La Grange point L2, will get to within a few hundred kilometers of Toutatis and pass it at a relative velocity of about 10.7 kilometers per second.

Interestingly, at about the same time, the Geminid Meteor Shower ought to be approaching its peak.

There will be two other more distant visitors this month. On December 23 SD220 and WT24 will make distant passes at 59.8 Lunar Distance and 69.2 Lunar Distance, respectively. After that we do not expect another visitor until February 2013.

For more detailed information about Toutatis, see the Asteroid 4179 Toutatis page at the JPL site Asteroid Radar Research, the Toutatis page at Calvin J. Hamilton’s Views of the Solar System site, or any of the other solid treatments of the asteroid available online, including Wikipedia.

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