As I'm writing this (13:40 UT) a newly-discovered asteroid, 2009 DD45, is flying past Earth at only 74,800 km (46,478.5 miles or 0.000482 AU) away. That's only about twice the height of a typical geostationary communications satellite, and well inside the moon's orbit. According to Spaceweather.com, the 30- to 40-meter wide space rock is similar in size to the Tunguska impactor of 1908, but this time there is no danger of a collision. At closest approach on March 2nd, (which just occurred) 2009 DD45 will speed through the constellation Virgo shining as brightly as an 11th magnitude star. So if you're in the Pacific region like Hawaii or Tahiti, go out and take a look! But this rock is moving fairly fast, and by tonight, it will only be 13th magnitude, and fading fast.
The asteroid was only discovered three days ago by the prolific asteroid hunter Robert McNaught at Siding Spring Observatory in Australia, when the space rock was already within 2,414,016 km (1½ million miles) of Earth and closing fast. If you want to try and track it, here's the ephemeris information from the Minor Planet Center.
Check out the video:46,000 miles!!! Holy !#@%! That’s too close for comfort. I’ve seen plenty of shows about the Tunguska incident and that would be devastating to a populated area.
And they only first spotted it 3 days prior