'Asteroid 2004 MN4' is about 320meters wide. Big enough to devastate an area as big as Texas if it hit land.
Its scarily close trajectory prompted some exact calculations by the Arecibo Radar telescope.
Astronomers now say it will fly past Earth, only 18,600 miles above the ground.
For comparison geosynchronous satellites orbit at 22,300 miles above ground.
At its closest approach it will be visible to the unaided eye, on Friday 13th 2029.
Story here.
http://science.nasa.gov/headlines/y2005/13may_2004mn4.htm?list111547
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"You will never find a real Human being - Even in a mirror." ....Mike Kremer.