Asteroid 2018 FK5 passed by the Earth at a distance of about 150 200
km (0.39 times the average distance between the Earth and the Moon, or
0.10% of the distance between the Earth and the Sun), slightly before 1.30 pm
GMT on Friday 30 March 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 FK5 has an estimated
equivalent
diameter of 4-13 m (i.e. it is estimated that a spherical object
with
the same volume would be 4-13 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 43 and 28 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2018 FK5. Minor Planet Center.
2018 FK5 was discovered on 28 March 2018 (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 2018 FK5
implies that the asteroid was the 235th object (object K5) discovered in the second half of March 2018 (period 2018 F).
2018
FK5 has a 400 day orbital period and an eccentric orbit
tilted at an angle of 12.1° to the plane of the Solar System, which
takes it from 0.74 AU from the Sun (i.e. 74% of he average distance at
which the Earth orbits the Sun, slightly outside the orbit of the planet Venus) to 1.38 AU from the Sun (i.e. 138% of
the
average distance at which the Earth 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 the
asteroid has occasional close encounters with the Earth, with the last thought to have happened in October 2008 and the
next predicted
in October 2019. The asteroid also has occasional close encounters with
the planet Venus, with the last thought to have happened in December 2011.
See also...
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