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 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented significant minor threat. 2013 BZ45 has an estimated equivalent diameter of 82-260 m (i.e. it is estimated that a spherical object with the same volume would be 82-260 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 700 megatonnes of TNT (roughly 41 000 times the energy of the Hiroshima bomb) and creating a crator about 4 km in diameter. Such an event would cause devastation over a wide area, and could cause climatic problems for decades.

 The calculated orbit of 2013 BZ45. JPL Small Body Database.

2013 BZ45 was discovered on 19 January 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 BZ45 implies that it was the 1150th asteroid (asteroid Z45) discovered in the secod half of January 2013 (period 2013 B). 

2013 BZ45 has a 373 day year orbital period and an eccentric orbit tilted at an angle of 5.3° to the plane of the Solar System, which takes it from 0.87 AU from the Sun (i.e. 87% of the average distance at which the Earth orbits the Sun) to 1.16 AU from the Sun (i.e. 1.16% of the average distance at which the Earth 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). This means that close encounters between the asteroid and Earth are extremely  common, with the last having occured in February 2014 this year and the next predicted in January 2016. As an asteroid probably larger than 150 m in diameter that occasionally comes within 0.05 AU of the Earth, 2013 BZ45 is also classified as a Potentially Hazardous Asteroid.

See also...

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Asteroid 2008 CQ passes the Earth.           Asteroid 2008 CQ passed by the Earth at a distance of 1 854 000 km (4.8 times the average distance between the Earth and the Moon, or 1.2 % of the average distance between the Earth and the Sun), at about 1.20 am GMT on Saturday 31 January 2015. There was no...

Asteroid 2015 BE passes the Earth.             Asteroid 2015 BE passed by the Earth at a distance of 11 890 000 km (30.91 times the average distance between the Earth and the Moon, or 7.9 % of the average distance between the Earth and the Sun), at about 8.25 am GMT on Friday 30 January 2015...

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