Asteroid 2017 RC passed by the Earth at a distance of about 928 000
km (2.41 times the average distance between the Earth and the Moon, or
0.62% of the distance between the Earth and the Sun), at about 5.20 pm
GMT on Monday 28 August 2017. There was no danger of
the asteroid hitting us, though were it to do so it would not have
presented a significant threat. 2017 RC has an estimated
equivalent
diameter of 4-16 m (i.e. it is estimated that a spherical object
with
the same volume would be 4-16 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 36 and 28 km above the ground, with only fragmentary material
reaching the Earth's surface.
The calculated orbit of 2017 RC Minor Planet Center.
2017 RC was discovered on 1 September 2017 (four 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 2017 RC
implies that the asteroid was the third object (object C) discovered in the first half of September 2017 (period 2017 C).
2017 RC has a 702 day orbital period and an eccentric orbit
tilted at an angle of 3.13° to the plane of the Solar System, which
takes it from 0.90 AU from the Sun (i.e. 90% of he average distance at
which the Earth orbits the Sun) to 2.20 AU from the Sun (i.e. 220% of
the
average distance at which the Earth orbits the Sun, more than the
distance at which the planet Mars orbits). This means that the asteroid has occasional close encounters with the Earth, with the next predicted in May 2019. 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).
See also...
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