Asteroid 2018 FD2 passed by the Earth at a distance of about 907 000
km (2.36 times the average distance between the Earth and the Moon, or
0.61% of the distance between the Earth and the Sun), slightly after 6.35 am
GMT on Saturday 17 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 FD2 has an estimated
equivalent
diameter of 8-26 m (i.e. it is estimated that a spherical object
with
the same volume would be 8-26 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 35 and 25 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2018 FD2. Minor Planet Center.
2018 FD2 was discovered on 19 March 2018 (two days after 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 FD2 implies that it was the 54th asteroid (asteroid D2)
discovered in the second half of March 2018 (period 2018 F).
2018 FD2 has a 434 day orbital period and an eccentric orbit
tilted at an angle of 14.8° to the plane of the Solar System, which
takes it from 0.68 AU from the Sun (i.e. 68% of he average distance at
which the Earth orbits the Sun, and inside the orbit of the planet Venus) to 1.59 AU from the Sun (i.e. 159% of
the
average distance at which the Earth orbits the Sun, and slightly outside the orbit of the 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 2018 EB4 has
occasional close encounters with the planet Earth, with
the last thought to have occurred in September 2016.
See also...
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