Asteroid 2018 BT6 passed by the Earth at a distance of about 7 010 000
km (18.2 times the average distance between the Earth and the Moon, or 4.69% of the distance between the Earth and the Sun), slightly after 9.50 pm
GMT on Friday 26 January 2018. There was no danger of
the asteroid hitting us, though were it to do so it would have
presented a significant threat. 2018 BT6 has an estimated
equivalent
diameter of 100-330 m (i.e. it is estimated that a spherical object
with
the same volume would be 100-330 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 225 to 8800 times as powerful as the
Hiroshima
bomb. Such an impact would result in an impact crater 1-5 km
in
diameter
and devastation on a global scale, as well as climatic effects that
would last years or even decades.
The calculated orbit of 2018 BT6. Minor Planet Center.
2018 BT6 was discovered on 27 January 2018 (the day after its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey,
which is located in the Catalina Mountains north of Tucson. The
designation 2018 BT6 implies that it was the 169th asteroid (asteroid T6)
discovered in the second half of January 2018 (period 2018 B).
2018 BT6 has a 1237 day orbital period and an eccentric orbit
tilted at an angle of 3.01° to the plane of the Solar System, which
takes it from 0.39 AU from the Sun (i.e. 39% of he average distance at
which the Earth orbits the Sun, and inside the orbit of the planet Mercury) to 4.12 AU from the Sun (i.e. 412% of
the
average distance at which the Earth orbits the Sun, and considerably
more than twice as far 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). As an asteroid probably larger than 150 m in diameter
that occasionally comes within 0.05 AU of the Earth, 2018 BT6 is also
classified as a Potentially Hazardous Asteroid.
See also...
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