Asteroid 2013 UR1 passed the Earth at a distance of 251 600 km (roughly 70% of the distance between the Earth and the moon) slightly after 10.05 pm on Monday 21 October 2013. There was no danger of the asteroid hitting us, and if it had done it would have presented little danger; 2013 UR1 is estimated to be between five and eighteen meters in diameter, and an asteroid this size would be expected to break up in the Earth's atmosphere between 40 and 20 km above the ground, with only fragmentary material reaching the planet's surface.
2013 UR1 was discovered on 23 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 UR1 implies that the asteroid was the 42nd object discovered in the second half of October 2013 (period 2013U).
2013 UR1 has a 3.35 year orbital period and an eliptical orbit that takes it from 0.60 AU from the Sun (i.e. 60% of the average distance at which the Earth orbits the Sun, slightly inside the orbit of Venus) to 3.88 AU from the Sun (i.e. 388% of the average distance at which the Earth orbits the Sun, more than twice as far from the Sun as the planet Mars). It is therefore classed as an Apollo Group Asteroid (an asteroid that is on average further from the Sun than the Earth, but which does get closer).