March17th.
ASTEROID FLYBY HAPPENED TONIGHT: Newly-discovered asteroid 2009 FH is flying past Earth tonight only 85,000 km away. That's about twice the altitude of a geosynchronous communications satellite. Advanced amateur astronomers in North America can photograph the 20-meter-wide space rock racing through the constellation Gemini after sunset on March 17th. It should be about as bright as a 14th magnitude star. [ephemeris] [3D orbit]
http://www.spaceweather.com/