Asteroid 2013 UU4 passes the Earth.

Asteroid 2013 UU4 passed the Earth at a a distance of 13 820 000 km (a little under 36 times the distance between the Earth and the Moon), slightly before 11.45 pm GMT on Friday 25 October 2013. There was no danger of the asteroid hitting us, though if it had of done it would have presented some danger. Asteroid 2013 UU4 is estimated to be between 30 and 94 m in diameter, and an object towards the upper end of this range would be capable of passing through our atmosphere reasonably intact, hitting the ground and creating a crater around a kilometer in diameter, as well as causing devastation over a wide area and global climatic effects lasting several years; although it would not be capable of effecting permanent change on a global scale.

The calculated orbit of 2013 UU4. JPL Small Body Database Browser.

2013 UU4 was discovered on 25 October 2013 (the day of its closest approach to the Earth) 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 UU4 implies that the asteroid was the 120th object discovered in the second half  of October 2013 (period 2013 U).

While 2013 UU4 occasionally comes near to the Earth, it does not actually cross our orbital path. It has an elliptical 560 day orbit that takes it from 1.07 AU from the Sun (1.07 times the distance at which the Earth orbits the Sun), slightly outside our orbit, to 1.59 AU from the Sun, just outside the orbit of Mars (though its orbit is tilted at a high angle to the Solar System, so the the only planet it ever nears is the Earth), 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 UQ1 passes the Earth, Asteroid 2013 TO69 passed the Earth, Asteroid 2012 ER14 flies by the Earth, Asteroid 2013 UU1 passes the Earth and Asteroid 2013 TK passes the Earth.

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