Asteroid 2014 WZ120 passed by the Earth at a distance of about 7 019 000 km (18.26 times the average distance between the Earth and the
Moon, or 4.7% of the average distance between the Sun and the Earth), at about 4.10 am GMT on Wednesday 3 December 2014. There was no
danger of the asteroid hitting us, though were it to do so it would have
presented a serious threat. 2014 WZ120 has an estimated
equivalent diameter of 160-490 m (i.e. it is estimated that a spherical
object with the same volume would be 160-490 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 with an
energy equivalent to about 80-4000 megatons of TNT (roughly 4700-235 000 times the energy of the Hiroshima bomb). Such an event
would result in a crater between 2.5 and 8 km across, cause devastation
on a global scale and would have the potential to affect the climate
globally for decades after the impact event.
The calculated orbit of 2014 WZ120. JPL Small Body Database Browser.
2014 WZ120 was discovered on 21 November 2014 (thirteen days before 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 2014 WZ120 implies that it was the 3025th asteroid (asteroid Z120)
discovered in the second half of November 2014 (period 2014 W).
2014 WZ120 has a 1203 day year orbital period and an eccentric
orbit tilted at an angle of 21° to the plane of the Solar System, which
takes it from 0.79 AU from the Sun (i.e. 79% of the average distance at
which the Earth orbits the Sun) to 3.63 AU from the Sun (i.e. 363% of
the average distance at which the Earth orbits the Sun, considerably more
than twice the distance at which the planet Mars orbits the Sun). 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 close encounters between the asteroid and Earth are
fairly common, with the
next predicted in April 2140. As an asteroid on a trajectory which
brings it extremely close to Earth which is large enough to cause
serious harm should it collide with Earth it is also classified as a
Potentially Hazardous Asteroid.
See also...
Asteroid 2014 WH6 passed by the Earth at a distance of 11 200 000 km
(29.13 times the average distance between the Earth and the Moon, or
7.5% of the average distance...
Asteroid 2014 WF201 passed by the Earth at a distance of 2 398 000 km
(6.24 times the average distance between the Earth and the Moon, or
0.016% of the average distance...
The Irish Astronomical Association has reported a fireball over County
Antrim in Northern Ireland at about 5.30 pm GMT on Tuesday 18 November
2014. The meteor was reportedly brighter than the Moon, and...
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