Asteroid 2015 BH514 passed by the Earth at a distance of 8 509 000 km (22.53 times the average distance between the Earth and the Moon, or 5.6 % of the average distance between the Earth and the Sun), slightly before 8.40 pm GMT on Wednesday 4 February 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented significant minor threat. 2015 BH514 has an estimated equivalent diameter of 43-140 m (i.e. it is estimated that a spherical object with the same volume would be 43-140 m in diameter), and an object towards the upper end of this range would be expected to be capable of passing through the atmosphere reasonably intact, impacting the ground in an explosion equivalent to about 200 megatonnes of TNT (roughly 12 000 times the energy of the Hiroshima bomb) and creating a crater over 2 km in diameter. Such an event would cause devastation over a wide area, and could cause climatic problems for decades.
The calculated orbit of 2015 BH514. JPL Small Body Database.
2015 BH514 was discovered on 16 January 2015 (eighteen days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 BH514 implies that it was the 12 858th asteroid (asteroid H514) discovered in the second half of January 2015 (period 2015 B).
2015 BH514 has a 435 day year orbital period and an eccentric orbit tilted at an angle of 33° to the plane of the Solar System, which takes it from 0.69 AU from the Sun (i.e. 69% of the average distance at which the Earth orbits the Sun, slightly inside the orbit of Venus) to 1.56 AU from the Sun (i.e. 1.56% of the average distance at which the Earth orbits the Sun, slightly outside the orbit of 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).
See also...
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Asteroid 2013 BZ45 passes the Earth. Asteroid 2013 BZ45 passed by the Earth at a distance of 9 670 000 km (25.16 times the average distance between the Earth and the Moon, or 6.5 % of the average distance between the Earth and the Sun), slightly before 8.30 pm GMT on Tuesday 3 February...
Asteroid 2015 BL passed by the Earth at a distance of 17 350 000 km (45.38 times the average distance between the Earth and the Moon, or 11.6 % of the average distance between the Earth and the Sun), slightly before 0.10 am GMT on Tuesday 3 February...
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