Asteroid 2013 UJ9 passed the Earth at a distance of 1 883 000 km (roughly 4.9 times the distance to the Moon), slightly after 8.00 am on Friday 1 November 2013. There was no danger of the asteroid hitting us and if it had done so it would have presented little danger. 2013 UJ9 is estimated to be between 9 and 30 m in diameter, and an object of this size would be expected to break up in the atmosphere between 32 and 16.5 km above the ground, with only fragmentary material reaching the Earth's surface.
2013 UJ9 was discovered on 30 October 2013 by the University of Arizona's Catalina Sky Survey in the Catalina Mountains north of Tucson. The designation 2013 UJ9 implies that it was the 234th asteroid discovered in the second half of October 2013 (period 2013 U).
2013 UJ9 has a 3.39 year orbital period and an eccentric orbit inclined to the plane of the Solar System that takes it from 0.97 AU from the Sun (i.e. 97% of the average distance at which the Earth orbits the Sun) to 3.54 AU from the Sun (i.e. 354% of the average distance at which the Earth orbits the Sun, more than twice the distance at which the planet Mars orbits the Sun). 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).
See also Asteroid 2013 UV3 passes between the Earth and the Moon, Asteroid 2013 VL detected after it passes the Earth, Asteroid 2013 UK9 passes the Earth, Asteroid 2013 UR1 flies between the Earth and the Moon and Asteroid 2013 UT3 passes by the Earth.
Follow Sciency Thoughts on Facebook.