We are going to get buzzed Tuesday. A reasonably large asteroid will pass quite close to the Earth, well inside lunar orbit. Asteroid 2005 YU55 will pass 325,000 km (202,000 mi) from the Earth. This is a good sized object, about 400m (1300ft) in diameter, large enough to create significant damage if it were to collide. We do know that the object will safely miss, this time. It is an object to track carefully. Data from this encounter and a future encounter with Venus in 2029 will set YU55 up for another encounter with Earth in 2041. Again we believe it will miss, but it will be close.
Keck 2 will be observing YU55 using adaptive optics and NIRC2 in an attempt to get high resolution imagery of the asteroid. It is quite convenient that this interesting asteroid is passing close to Earth, it will be in easy reach of our best astronomical instrumentation. I suspect I will be spending a little time in Keck 2 remote operations Tuesday night to get a look for myself.