Asteroid 2013 RM73, a 20 m diameter object, passed the Earth at a distance of 875 000 km, or 2.6 times as distant as the Moon, on Tuesday 17 September 2013. The object was only discovered a few days before it passed us - the name 2013 RM73 means the 1837th object discovered in the first two weeks of September 2013 (period 2013 R) - but presented no significant threat to the Earth; an obtect this size is predicted to break up explosively at an altitude of 22.4 km if it did hit us, with only small fragments of material reaching the ground.
2013 RM73 is calculated to have a 2.4 year orbital period, which takes it slightly inside the orbit of the Earth, and some way outside the orbit of Mars. It is predicted to make another close pass of the Earth in September 2025, and then again in December 2106.
See also Asteroid 2013 RT73 flies past the Earth, Asteroid 2013 RS43 misses the Earth, The dust tail of 3200 Phaethon, The Perseid Meteors and The perihelion of Comet 103P/Hartley 2.
Follow Sciency Thoughts on Facebook.