A house-sized asteroid is set to miss Earth by a whisker later today, passing just 7,600 miles above the surface.
Near-Earth asteroid 2011 MD will reach its closest point to Earth at about 1:00 PM EDT, passing over the southern Atlantic Ocean. On its way back out again, after its orbit's been bent by gravity, it will actually pass well inside the ring of geostationary man-made satellites orbiting the Earth.
The asteroid is in a very Earth-like orbit about the Sun, says NASA - indeed, some astronomers reckon it may actually be a piece of space junk.
However, an analysis of its orbit indicates there's no chance it will actually hit us. In any case, at just 5-20 meters in diameter, it would most likely fragment and burn up before impact if it did. There is a tiny chance, though, that it could hit a man-made satellite.
The asteroid was discovered by the LINEAR near-Earth object discovery team in Socorro, New Mexico, just last week.
An object of this size comes this close to Earth about every six years on average. For a short time, it will be bright enough to be seen even with a modest-sized telescope. California, Hawaii and Australia should get a good view.
A lager asteroid is due to buzz the Earth on November 8 this year. Near-Earth asteroid 2005 YU55, which is around 400 meters across, will pass within 0.85 lunar distances from the Earth.
NASA says it poses no threat of an Earth collision for at least 100 years. However, it will be the closest yet approach by an object this large that we know about in advance. Nothing comparable will happen again until 2028 when asteroid (153814) 2001 WN5 will pass within 0.6 lunar distances of the Earth.