Asteroid 2020 QD passed by the Earth at a distance of about 10 662
000
km (27.8 times the average distance between the Earth and the Moon, or 7.13% of the distance between the Earth and the Sun), at about 4.45 pm
GMT on Thursday 17 September July 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 QD has an estimated
equivalent
diameter of 100-320 m (i.e. it is estimated that a spherical object
with
the same volume would be 100-320 m in diameter), and an object of this
size 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 200-17 500 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater roughly 1.2-3.5 km
in
diameter
and devastation on a global scale, as well as climatic effects that
would last years or even decades.
2020 QD was discovered on 16 August 2020 (over a month before its closest encounter with the Earth) by the University of Hawaii's PANSTARRS telescope. The
designation 2020 QD implies that it was the fourth asteroid (asteroid D -
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 D = 4)
discovered in the second half of August 2020 (period 2020 Q).
2020 QD has a 1359 day (3.72 year) orbital period, with an elliptical
orbit tilted at
an angle of 4.00° to the plain of the Solar System which takes in to
0.65 AU from the Sun (65% of the distance at which the Earth orbits the
Sun, and slightly inside the orbit of the planet Venus) and out to 4.15 AU (415% of the distance at which the Earth orbits
the sun and more than twice as far 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 March 2017 and the next predicted
in January 2032. 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 QD is also classified
as a Potentially Hazardous Asteroid.
2020 QD also
has occasional close encounters with the planets Venus, which it last came close to in February 2017 and is next predicted to
pass in January 2084, Mars, which it last cam close to in May 1965 and is next predicted to
pass in May 2024, and Jupiter, which it last came close to in Arpil 2019 and is
expected to pass again in January 2067. 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...
