Asteroid 2019 CM5 passed by the Earth at a distance of about 531 500
km (1.38 times the average distance between the Earth and the Moon, or
0.36% of the distance between the Earth and the Sun), slightly before 3.05 pm
GMT on Friday 8 February 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 CM5 has an estimated
equivalent
diameter of 5-16 m (i.e. it is estimated that a spherical object
with
the same volume would be 5-16 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 40 and 25 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2019 CM5. JPL Small Body Database.
2019 CM5 was discovered on 11 February 2019 (three days 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 CM5
implies that the asteroid was the 130th object (object M5 - in numbering asteroids the letters A-Y, excluding I, are assigned
numbers from 1 to 24, so that M5 = (24 x 5) + 10 = 130) discovered in the first half of February 2019 (period 2019 C).
2019 CM5 has an 766 day orbital period and an eccentric orbit
tilted at an angle of 0.40° to the plane of the Solar System, which
takes it from 0.98 AU from the Sun (i.e. 98% of the the average distance
at
which the Earth orbits the Sun) to 2.29 AU from the Sun (i.e. 229% of
the
average distance at which the Earth orbits the Sun, and somewhat more than 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 extremely common, with the
last having occurred in April 2017 and the next predicted
in April 2126.
See also...
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