Asteroid 2020 FX4 passed by the Earth at a distance of about 18 206 000
km (47.4 times the average distance between the Earth and the Moon, or 12.2% of the distance between the Earth and the Sun), slightly after 0.10 am
GMT on Wednesday 25 March 2020. There was no danger of
the asteroid hitting us, though were it to do so it would have
presented a considerable threat. 2020 FX4 has an estimated
equivalent
diameter of 88-280 m (i.e. it is estimated that a spherical object with
the same volume would be 88-280 m in diameter), and an object at the upper end of this range would be predicted to be capable of passing
through the Earth's
atmosphere relatively intact, impacting the ground directly with an
explosion that would be 60 000 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater over 4 km in
diameter
and devastation on a global scale, as well as climatic effects that
would last years or even decades.
2020 FX4 was discovered on 24 March 2020 (the day before its closest encounter with the Earth) by the University of Hawaii's PANSTARRS telescope. The
designation 2012 DJ61 implies that it was the 119th asteroid (asteroid X4 -
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., which means that X4 = 23 + (24 X 4) = 119)
discovered in the second half of March 2020 (period 2020 F).
2020 FX4 has a 1389 day (3.80 year) orbital period, with an elliptical
orbit tilted at
an angle of 9.88° to the plain of the Solar System which takes in to
0.97 AU from the Sun (97% of the distance at which the Earth orbits the
Sun) and out to 3.90 AU (3.9% of the distance at which the Earth orbits
the sun and more than twice as from the Sun as the planet Mars).
This means that close
encounters between the asteroid and Earth are fairly common, with the
last thought to have happened in April 2001 and the next predicted
in March 2043. 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). As
an asteroid probably larger than 150 m in diameter that occasionally
comes within 0.05 AU of the Earth, 2020 FX4 is also classified
as a Potentially Hazardous Asteroid.
See also...
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