Asteroid 2020 NK1 passed by the Earth at a distance of about 8 228
000
km (21.4 times the average distance between the Earth and the Moon, or
5.50% of the distance between the Earth and the Sun), slightly before 9.00 pm
GMT on Friday 31 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 NK1 has an estimated
equivalent
diameter of 300-940 m (i.e. it is estimated that a spherical object
with
the same volume would be 300-940 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 65 000-2 650 000 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater roughly 4-13 km
in
diameter
and devastation on a global scale, as well as climatic effects that
would last decades or even centuries.
Radar range-Doppler image of 2020 NK1 taken on July 2020. The image resolution in the vertical dimension is 30 m per pixel. Arecibo Observatory/NSF/NASA.
2020 NK1 was discovered on 13 July 2020 (18 days before its closest approach to the Earth), by he 0.5-m Asteroid Terrestrial-Impact Last Alert System telescope on Mauna Loa in Hawaii. The
designation 2020 NK1 implies that it was the 34th asteroid (asteroid K1 -
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 K1 = (24 x 1) + 10 = 34)
discovered in the first half of July 2020 (period 2020 N - the
year being split into 24 half-months represented by the letters A-Y, with I being excluded).
The orbit of 2020 NK1, and its current position. JPL Small Body Database.
2020 NK1 has a 601 day (1.65 year) orbital period, with an elliptical
orbit tilted at
an angle of 45.4° to the plain of the Solar System which takes in to
0.49 AU from the Sun (49% of the distance at which the Earth orbits the
Sun, and slightly outside the orbit of the planet Venus) and out to 2.30 AU (230% of the distance at which the Earth orbits
the Sun, and comsiderably outside the orbit of 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 2019 and the next predicted
in February 2024. 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 NK1 is also classified
as a Potentially Hazardous Asteroid. 2020 NK1 also
has occasional close encounters with the planets Venus, which it last
came close to in December 1959 and is next predicted to
pass in August 2030.
See also...
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