Asteroid 2020 DM4 passed by the Earth at a distance of about 7 063 000
km (18.4 times the average distance between the Earth and the Moon, or 4.72% of the distance between the Earth and the Sun), at about 10.05 am
GMT on Friday 1 May 2020. There was no danger of
the asteroid hitting us, though were it to do so it would have
presented a considerable threat. 2020 DM4 has an estimated
equivalent
diameter of 84-260 m (i.e. it is estimated that a spherical object with
the same volume would be 84-260 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 35 000 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater almost 4 km in
diameter
and devastation on a global scale, as well as climatic effects that
would last decades or even centuries.
2020 DM4 was discovered on 26 February 2020 (over two months before its closest encounter with the Earth) by the Purple Mountain Observatory of the Chinese Academy of Sciences. The
designation 2020 DM4 implies that it was the 108th 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 M4 = 12 + (24 X 4) = 108)
discovered in the second half of February 2020 (period 2020 D).
2020 DM4 has a 947 day (2.59 year) orbital period, with an elliptical
orbit tilted at
an angle of 4.12° to the plain of the Solar System which takes in to 1.02 AU from the Sun (102% of the distance at which the Earth orbits the
Sun) and out to 2.75 AU (275% of the distance at which the Earth orbits
the sun and further from the Sun than the planet Mars).
This means that close
encounters between the asteroid and Earth are fairly common, with the
last thought to have happened in June 2007 and the next predicted
in April 2033. It is therefore
classed as an Amor Group Asteroid (an asteroid which comes close to the
Earth, but which is never closer to the Sun than the Earth is). As
an asteroid probably larger than 150 m in diameter that occasionally
comes within 0.05 AU of the Earth, 2020 DM4 is also classified
as a Potentially Hazardous Asteroid. 2020 DM4 also has occassional close encounters with the planet Mars, with
the last having happened in June 2004, and the next predicted for January 2075.
See also...
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