Asteroid
2016 WH passed by the Earth at a distance of 900 100 km (2.34 times the
average distance between the Earth and the Moon, 0.60% of the average
distance
between the Earth and the Sun), at about 0.05 am GMT on Monday 21
November 2016. There was no danger of the asteroid hitting us, though
had it
done so it would have presented no threat. 2016 WH has an estimated
equivalent diameter of 7-24 m (i.e. it is estimated that a spherical
object
with the same volume would be 7-24 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 37 and 20 km above the ground, with only
fragmentary
material reaching the Earth's surface.
The calculated orbit of 2016 WH. Minor Planet Center.
2016 WH was discovered on 19 November 2016 (two 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 WH
implies that the asteroid was the eigtht object (object H) discovered in the second half of November 2016 (period 2016 W).
2016 WH is calculated to have a 741 day orbital
period and an elliptical orbit tilted at an angle of 2.74° to the plain of the
Solar System that takes it from 0.84 AU from the Sun (i.e. 84% of the average
distance at which the Earth orbits the Sun) to 2.36 AU from the Sun (i.e. 236%
of the average distance at which the Earth orbits the Sun, more than 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). This means that it has occassional close encounters with the Earth, with the last having occured in November 2014.
See also...
Follow Sciency Thoughts on Facebook.
