Asteroid 2013 WD44 passed by the Earth at a distance of 8 901 000 km (slightly over 23 times the distance between the Earth and the Moon) a little after 9.30 pm GMT on Monday 23 December 2013. There was no danger of the asteroid hitting us, and had it done so it would not have presented any danger. 2013 WD44 is estimated to be between 14 and 43 m in diameter, and an object of this size would be expected to break up in the atmosphere between 27 and 10 km above the Earth's surface, with only fragmentary material reaching the ground.
The calculated orbit of 2013 WD44. JPL Small Body Database Browser.
2013 WD44 was discovered on 28 November 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 WD44 implies that the asteroid was the 1104th object discovered in the second half of November 2013 (period 2013 W).
While 2013 WD44 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 770 day orbit that takes it from 1.03 AU from the Sun (1.03 times the distance at which the Earth orbits the Sun), slightly outside our orbit, to 2.26 AU from the Sun, (2.26 times the distance at which the Earth orbits the sun and considerably outside the orbit of the planet 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 2013 XA4 passes the Earth, Asteroid 2013 XY20 passes the Earth, Asteroid 2013 XW8 passes the Earth, Asteroid 2013 UC1 passes the Earth and Asteroid 138095 (2000 DK79) passes the Earth.
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