Asteroid 2019 FC1 passed by the Earth at a distance of about 103 200
km (0.27 times the average distance between the Earth and the Moon, or
0.07% of the distance between the Earth and the Sun), slightly after 5.45 am
GMT on Thursday 28 March 2019. There was no danger of
the asteroid hitting us, though were it to do so it would not have
presented a significant threat. 2019 FC1 has an estimated
equivalent
diameter of 14-45 m (i.e. it is estimated that a spherical object
with
the same volume would be 14-45 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 28 and 10 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2019 FC1. JPL Small Body Database.
2019 FC1 was discovered on 29 March 2019 (the day after 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 2019 FC1
implies that the asteroid was the 27th object (object C1 - in numbering asteroids the letters A-Y, excluding I, are assigned
numbers from 1 to 24, so that M5 = (24 x 1) + 3 = 27) discovered in the second half of March 2019 (period 2019 F).
2019 FC1 has an 1202 day orbital period and an eccentric orbit
tilted at an angle of 1.98° to the plane of the Solar System, which
takes it from 0.43 AU from the Sun (i.e. 43% of the the average distance
at
which the Earth orbits the Sun, and slightly outside the orbit of Mercury) to 3.99 AU from the Sun (i.e. 399% of
the
average distance at which the Earth orbits the Sun, and somewhat more than twice the distance at
which Mars orbits). 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 close
encounters between the asteroid and Earth are common, with the
last having occurred in October 1981 and the next predicted
in October 2071.
2019 FC1 also
has frequent close encounters with the planets Venus, which it last came close to in November 1984 and is next predicted to
pass in December 2071, Mars, which it last passed in October 1984 and Jupiter, which it last came close to in October 1983
and
is next predicted to pass in January 2067. Asteroids
which make close passes to multiple planets are considered to be in
unstable orbits, and are often eventually knocked out of these orbits by
these encounters, either being knocked onto a new, more stable orbit,
dropped into the Sun, knocked out of the Solar System or occasionally
colliding with a planet.
See also...
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