Asteroid 2015 CG passed by the Earth at a distance of 2 729 200 km (7.1 times the average distance between the Earth and the Moon, or 1.8 % of the average distance between the Earth and the Sun), slightly before 1.15 pm GMT on Wednesday 11 February 2015. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2015 CG has an estimated equivalent diameter of 14-45 m (i.e. it is estimated that a spherical object with the same volume would be 14-45 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 ground, with only fragmentary material reaching the Earth's surface.
The calculated orbit of 2015 CG. JPL Small Body Database.
2015 CG was discovered on 7 February 2015 (four days before 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 2015 CG implies that it was the 7th asteroid (asteroid G) discovered in the first half of February 2015 (period 2015 C).
2015 CG has a 1170 day year orbital period and an eccentric orbit tilted at an angle of 4.6° to the plane of the Solar System, which takes it from 0.90 AU from the Sun (i.e. 90% of the average distance at which the Earth orbits the Sun) to 3.44 AU from the Sun (i.e. 344% of the average distance at which the Earth orbits the Sun, considerably more than twice the distance at which the planet Mars 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).
See also...
Asteroid 2015 CT13 passed by the Earth at a distance of 708 200 km (1.84 times the average distance between the Earth and the Moon, or 0.47 % of the average distance between the Earth and the Sun), slightly after 9.25 am GMT on Wednesday 11 February...
Asteroid 2015 CH13 passes the Earth. Asteroid 2015 CH13 passed by the Earth at a distance of 282 400 km (0.73 times the average distance between the Earth and the Moon, which is to say inside the orbit of the Moon, though the Moon was on the opposite side of the Earth at the time, or 0.19% of...
Asteroid 2015 BP4 passed by the Earth at a distance of 15 770 000 km (40.96 times the average distance between the Earth and the Moon, or 10.5 % of the average distance between the Earth and the Sun), at about 3.15 am GMT on Wednesday 11 February...
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