Asteroid 2020 JN1 passed by the Earth at a distance of about 440 100
km (1.15 times the average distance between the Earth and the Moon, or 0.29% of the distance between the Earth and the Sun), slightly before 9.10 am
GMT on Saturday 16 May 2020. There was no danger of
the asteroid hitting us, though were it to do so it would not have
presented a significant threat. 2020 JN1 has an estimated
equivalent
diameter of 3-9 m (i.e. it is estimated that a spherical object
with
the same volume would be 3-9 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
more than 33 km above the ground, with only fragmentary material
reaching the Earth's surface.
2020 JN1 was discovered on 14 May 2020 (two days before its closest encounter with 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 2020 JN1 implies that the asteroid was the 37th object (asteroid N1 -
in numbering asteroids the letters A-Y, excluding I, are assigned
numbers from 1 to 24, with a number added to the end each time the
alphabet is ended, so that A = 1, A1 = 25, A2 = 49, etc, so that N1 = 24 + 13 = 37) discovered in the first half of May 2020 (period 2020 J - the
year being split into 24 half-months represented by the letters A-Y, with I being excluded).
2020 JN1 has an 1506 day (4.12 year) orbital period and an eccentric orbit
tilted at an angle of 7.18° to the plane of the Solar System, which
takes it from 0.75 AU from the Sun (i.e. 75% of the the average distance at
which the Earth orbits the Sun, and slightly outside the orbit of Venus) to 4.39 AU from the Sun (i.e. 4.39% of
the
average distance at which the Earth orbits the Sun, almost three times 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). 2020 JN1 is calculated to have had one previous close encounter with the Earth, in October 1953, preceded by a close encounter with Jupiter in April 1943. It is expected to have a close encounter with the planet Venus in June this year (2020), followed by another close encounter with Jupiter in June 2029, after which it is expected tio have no further close encounters with Inner Solar System bodies.
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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