Asteroid 2013 UC1 passed the Earth at a distance of 9 179 000 km (a little under 24 times the distance between the Earth and the Moon) slightly after 7.55 am GMT on Tuesday 12 November 2013. There was no danger of the asteroid hitting us, and had it done so it would have presented little threat. 2013 UC1 is estimated to be between 22 and 68 m in diameter, and an object of this size would be expected to break up in the atmosphere between 20 and 4 km above the Earth's surface, with only fragmentary material reaching the ground, although being directly beneath an object towards the upper end of this range would probably be fairly unpleasant.
The calculated orbit of 2013 UC1. JPL Small Body Database Browser.
2013 UC1 was discovered on 22 October 2013 by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2013 UC1 implies that the asteroid was the 28th object discovered in the second half of October 2013 (period 2013 U).
While 2013 UC1 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 722 day orbit that takes it from 1.04 AU from the Sun (1.04 times the distance at which the Earth orbits the Sun), slightly outside our orbit, to 2.11 AU from the Sun, considerably outside the orbit of Mars, so unless an encounter with another body causes it's orbital path to alter in a very specific way (highly unlikely) there is no chance of it hitting the Earth. As a Near Earth Object that remains strictly outside the orbit of the Earth it is classed as an Amor Family Asteroid.
See also Asteroid 138095 (2000 DK79) passes the Earth, Asteroid 2013 VQ13 discovered after it passes the Earth, Asteroid 2013 UL9 passes the Earth, Asteroid 2013 UR4 passes the Earth and Asteroid 2013 TY5 passed the Earth.
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