Sciency Thoughts: Asteroid 2008 WK32 passes the Earth.

Asteroid 2008 WK32 passed by the Earth at a distance of about 10 900 000 km (28.35 times the average distance between the Earth and the Moon), slightly after 1.20 pm on Sunday 1 June 2014. There was no danger of the asteroid hitting us, though were it to do so it would have presented a considerable threat. 2008 WK32 has an estimated equivalent diameter of 260-820 m (i.e. it is estimated that a spherical object with the same volume would be 260-820 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 47 000-1 175 000 times as powerful as the Hiroshima bomb. Such an impact would result in an impact crater 4-12 km in diameter and devastation on a global scale, as well as climatic effects that would last centuries.

The calculated orbit of 2008 WK32. JPL Small Body Database Browser.

2008 WK32 was discovered on 21 November 2008 by the Spacewatch Project at the University of Arizona's Lunar and Planetary Laboratory. The designation 2008 WK32 implies that it was the 811th asteroid (asteroid K32) discovered in the second half of November 2008 (period 2008 W).

2008 WK32 has an 603 day year orbital period and an eccentric orbit tilted to the plane of the Solar System that takes it from 0.87 AU from the Sun (i.e. 87% of the average distance at which the Earth orbits the Sun) to 1.93 AU from the Sun (i.e. 193% of the average distance at which the Earth orbits the Sun, considerably more than 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).

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