Asteroid 2012 MS4 passed by the Earth at a distance of about 12 249 000
km (31.9 times the average distance between the Earth and the Moon, or 8.19% of the distance between the Earth and the Sun), slightly before 10.00 pm
GMT on Thursday 20 December 2018. There was no danger of
the asteroid hitting us, though were it to do so it would have
presented a significant threat. 2012 MS4 has an estimated
equivalent
diameter of 340-1100 m (i.e. it is estimated that a spherical object
with
the same volume would be 340-1100 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 between 880 and 3 000 000 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater between 5 and 15 km
in
diameter
and devastation on a global scale, as well as climatic effects that
would last decades or even centuries.
The calculated orbit of 2018 EB Minor Planet Center.
2012 MS4 was discovered on 19 June 2012 by the Massachusetts Institute of Technology's Lincoln Near Earth Asteroid Research Laboratory in Socorro, New Mexico. The designation 2012 MS4 implies that it was the 118th asteroid
(asteroid S4) discovered in the second half of June 2012 (period
2012 S4).
2012 MS4 has a 1245 day orbital period and an eccentric orbit
tilted at an angle of 67.7° to the plane of the Solar System, which
takes it from 0.63 AU from the Sun (i.e. 63% of he average distance at
which the Earth orbits the Sun, inside the orbit of the planet Venus) to 3.90 AU from the Sun (i.e. 390% of
the
average distance at which the Earth orbits the Sun, and more than twice
as distant from the Sun than the planet Mars). 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). This means that the
asteroid has occasional close encounters with the Earth, with the
last having occurred in June 2012 and the next predicted
in June 2029. As an asteroid probably larger than 150 m in diameter
that occasionally comes within 0.05 AU of the Earth, 2012 MS4 is also
classified as a Potentially Hazardous Asteroid.
See also...
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