Asteroid 2019 CB2 passed by the Earth at a distance of about 1 044 000
km (2.72 times the average distance between the Earth and the Moon, or
0.70% of the distance between the Earth and the Sun), at about 1.20 am
GMT on Sunday 10 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 CB2 has an estimated
equivalent
diameter of 12-38 m (i.e. it is estimated that a spherical object
with
the same volume would be 12-38 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 12 km above the ground, with only fragmentary material
reaching the Earth's surface.
2019 CB2 was discovered on 5 February 2019 (five days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope. The designation 2019 CB2
implies that the asteroid was the 50th object (object B2 - in numbering asteroids the letters A-Y, excluding I, are assigned
numbers from 1 to 24, so that B2 = (24 x 2) + 2 = 50) discovered in the first half of February 2019 (period 2019 C).
2019 CB2 has an 455 day orbital period and an eccentric orbit
tilted at an angle of 6.16° to the plane of the Solar System, which
takes it from 0.69 AU from the Sun (i.e. 69% of the the average distance
at
which the Earth orbits the Sun and slightly inside the orbit of Venus) to 1.62 AU from the Sun (i.e. 1.62% of
the
average distance at which the Earth orbits the Sun, and slightly 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 February 2014 and the next predicted
in September 2020. 2019 CB2 also has occasional close encounter with the
planet Venus, with the last having happened in May 2014 and the next predicted for April 2060.
See also...
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