Asteroid 2013 BS45 passed by the Earth at a distance of 13 380 000 km (34.8 times the average distance between the Earth and the Moon, or 8.9 % of the average distance between the Earth and the Sun), slightly after 11.15 am GMT on Monday 9 February 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2013 BS45 has an estimated equivalent diameter of 12-39 m (i.e. it is estimated that a spherical object with the same volume would be 12-39 m in diameter), and an object of this size would be expected to break up in the atmosphere between 30 and 12 km above the ground, with only fragmentary material reaching the Earth's surface.
The calculated orbit of 2013 BS45. JPL Small Body Database.
2013 BS45 was discovered on 20 January 2013 by the University of Arizona's Kitt Peak-Spacewatch Project at the Steward Observatory in the Catalina Mountains north of Tucson. The designation 2013 BS45 implies that it was the 1143rd asteroid (asteroid S45) discovered in the second half of January 2013 (period 2013 B).
2013 BS45 has a 362 day orbital period, with an elliptical orbit tilted at an angle of 0.8° to the plain of the Solar System which takes in to 0.91 AU from the Sun (91% of the distance at which the Earth orbits the Sun) and out to 1.08 AU (8% further away from the Sun than the Earth). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in February 2013 and the next predicted in February 2016. Although it does cross the Earth's orbit and is briefly further from the Sun on each cycle, 2013 BS45 spends most of its time closer to the Sun than we are, and is therefore classified as an Aten Group Asteroid.
See also...
Asteroid 2015 CM passed by the Earth at a distance of 3 236 000 km (8.42 times the average distance between the Earth and the Moon, or 2.2 % of the average distance between the Earth and the Sun), slightly before 8.40 am GMT on Monday 9 February...
Asteroid 2015 CL passes the Earth. Asteroid 2015 CL passed by the Earth at a distance of 1 659 000 km (4.32 times the average distance between the Earth and the Moon, or 1.1 % of the average distance between the Earth and the Sun), at about 1.20 slightly before 10.40 pm GMT on Sunday 8 February...
Asteroid 2015 BF92 passes the Earth. Asteroid 2015 BF92 passed by the Earth at a distance of 3 267 000 km (8.5 times the average distance between the Earth and the Moon, or 2.2 % of the average distance between the Earth and the Sun), slightly before 10.10 pm GMT on Saturday 7 February...
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