Asteroid 2018 GN passed by the Earth at a distance of about 430 200
km (1.12 times the average distance between the Earth and the Moon, or
0.23% of the distance between the Earth and the Sun), slightly before 3.00 pm
GMT on Monday 9 April 2018. There was no danger of
the asteroid hitting us, though were it to do so it would not have
presented a significant threat. 2018 GN has an estimated
equivalent
diameter of 11-34 m (i.e. it is estimated that a spherical object
with
the same volume would be 11-34 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 15 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2018 GN. Minor Planet Center.
2018 GN was discovered on 8 April 2018 (the day before its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey,
which is located in the Catalina Mountains north of Tucson. The
designation 2018 GN implies that it was the 13th asteroid (asteroid N)
discovered in the first half of April 2018 (period 2018 G).
2018 GN has a 1370 day orbital period and an eccentric orbit
tilted at an angle of 1.44° to the plane of the Solar System, which
takes it from 0.64 AU from the Sun (i.e. 64% of he average distance at
which the Earth orbits the Sun, inside the orbit of the planet Venus) to 4.19 AU from the Sun (i.e. 419% of
the
average distance at which the Earth orbits the Sun, and more than twice as distant from the Sun than the planet Mars). 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 the asteroid has occasional close
encounters with the Earth, with the next predicted
in April 2071. The asteroid also has occasional encounters with the planet Jupiter, with the last having occurred in January 1990.
See also...
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