Asteroid
2016 WG7 passed by the Earth at a distance of 1 002 000 km (2.61 times the
average distance between the Earth and the Moon, 0.67% of the average
distance
between the Earth and the Sun), at about 3.55 pm GMT on Thursday 1 December 2016. There was no danger of the asteroid hitting us, though
had it
done so it would have presented no threat. 2016 WG7 has an estimated
equivalent diameter of 12-38 m (i.e. it is estimated that a spherical
object
with the same volume would be 12-38 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 10 km above the ground, with only
fragmentary
material reaching the Earth's surface.
The calculated orbit of 2016 WG7. Minor Planet Center.
2016 WG7 was discovered on 25 November 2016 (six 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 2016 WG7
implies that the asteroid was the 182nd object (object G7) discovered in the second half of November 2016 (period 2016 W).
2016 WG7 has a 340 day orbital period, with an elliptical orbit tilted at
an angle of 4.53° to the plain of the Solar System which takes in to
0.75 AU from the Sun (75% of the distance at which the Earth orbits the
Sun; slightly outside the orbit of the planet Venus) and out to
1.16 AU (16%
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 March this year and the next predicted
in November 2017. 2016 WG7 also has frequent close encounters with the
planet Venus, with the next predicted forJuly 2024. Although it does cross the Earth's
orbit and is briefly
further from the Sun on each cycle, 2016 WG7 spends most of its time
closer to the Sun than we are, and is therefore classified as an Aten
Group Asteroid.
See also...
