Asteroid
2015 XE1 passed by the Earth at a distance of 5 080 000 km (13.2
times the average distance between the Earth and the Moon, or 3.40% of
the average distance between the Earth and the Sun),
slightly before 3.00 am GMT on Saturday 19 December 2015. There was no
danger
of the asteroid
hitting us, though had it done so it would have presented only a minor
threat. 2015 XE1 has an estimated equivalent diameter of 13-41 m (i.e.
it is estimated that a spherical object with the same volume would be 13-41 m in diameter), and an object of this size would be expected to
explode in an airburst (an explosion caused by superheating from
friction with the Earth's atmosphere, which is greater than that caused
by simply falling, due to the orbital momentum of the asteroid) in the
atmosphere between 30 and 12 km above the ground, with only fragmentary
material reaching the Earth's surface.
2015 XE1 was discovered on 2 December 2015 (seven days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 XE1 implies that it was the 30th asteroid (asteroid E1) discovered in the first half of December 2015 (period 2015 X).
2015 XE1 has a 694 day orbital period and an eccentric orbit tilted at an angle of 3.91° to the plane of the Solar System that takes it from 0.997 AU from the Sun (i.e. 99.7% of the average distance at which the Earth orbits the Sun) to 2.07 AU from the Sun (i.e. 207% of the average distance at which the Earth orbits the Sun, considerably more than the distance at which 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). 2015 XE has occasional close encounters with the planet Earth, with the next predicted in February 2052.
See also...
Asteroid 2015 XX169 passes the Earth. Asteroid
2015 XX169 passed by the Earth at a distance of 3 231 000 km (8.41
times the average distance between the Earth and the Moon, or 2.16% of
the average distance between the Earth and the Sun),
slightly after 3.00 pm GMT on Monday 14...
2015 XE1 was discovered on 2 December 2015 (seven days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2015 XE1 implies that it was the 30th asteroid (asteroid E1) discovered in the first half of December 2015 (period 2015 X).
2015 XE1 has a 694 day orbital period and an eccentric orbit tilted at an angle of 3.91° to the plane of the Solar System that takes it from 0.997 AU from the Sun (i.e. 99.7% of the average distance at which the Earth orbits the Sun) to 2.07 AU from the Sun (i.e. 207% of the average distance at which the Earth orbits the Sun, considerably more than the distance at which 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). 2015 XE has occasional close encounters with the planet Earth, with the next predicted in February 2052.
See also...
Asteroid 2015 XX169 passes the Earth. Asteroid
2015 XX169 passed by the Earth at a distance of 3 231 000 km (8.41
times the average distance between the Earth and the Moon, or 2.16% of
the average distance between the Earth and the Sun),
slightly after 3.00 pm GMT on Monday 14...
Asteroid 2015 XA169 passes the Earth. Asteroid
2015 XA169 passed by the Earth at a distance of 2 848 000 km (7.41
times the average distance between the Earth and the Moon, or 1.90% of
the average distance between the Earth and the Sun),
slightly before 3.00 pm GMT on Saturday 12...
Asteroid 2015 XV261 passes the Earth. Asteroid
2015 XV261 passed by the Earth at a distance of 2 609 000 km (6.78
times the average distance between the Earth and the Moon, or 1.75% of
the average distance between the Earth and the Sun),
slightly after 3.05 am GMT on Tuesday 8 December...
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