Asteroid 2013 RF74 passed by the Earth earlier today (18 September 2013) at its closest reaching a distance of 2.1 million km (5.5 times as far away as the Moon). The 25 m asteroid was only discovered a few days before it passed by us; the name 2013 RF74 indicates that it was the 1856th object discovered in the first half of September 2013 (period 2013 R). An object of this size presents little danger to us, it would probably break up in the atmosphere at an altitude of 18-20 km if it did hit us, with only small fragments of debris reaching the surface.
2013 RF74 is calculated to have an elliptical 3.77 year orbit which brings it slightly within that of the Earth and which at its furthest rakes it more than twice as far from the Sun as Mars.
See also Asteroid 2013 RM73 passes the Earth, Asteroid 2013 RT73 flies past the Earth, Asteroid 2013 RS43 misses the Earth, The dust tail of 3200 Phaethon and The Perseid Meteors.
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