Thursday 14 July 2016

Asteroid 2016 NK22 passes the Earth.

Asteroid 2016 NK22 passed by the Earth at a distance of 264 500 km (0.69 times the average distance between the Earth and the Moon, or 0.18% of the average distance between the Earth and the Sun), at about 1.15 pm GMT on Monday 11 July 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented no threat. 2016 NK22 has an estimated equivalent diameter of 2-9 m (i.e. it is estimated that a spherical object with the same volume would be 2-9 m in diameter), and an object of this size would be expected to explode in an airburst (an explosion caused by superheating from friction with the Earth's atmosphere, which is greater than that caused by simply falling, due to the orbital momentum of the asteroid) in the atmosphere over 32 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of 2016 NK22JPL Small Body Database.

2016 NN22 was discovered on 9 July 2016 (two days before its closest approach to the Earth) by the University of Arizona's Mt. Lemmon Survey at the Steward Observatory on Mount Lemmon in the Catalina Mountains north of Tucson. The designation 2016 NN22 implies that the asteroid was the 655th object (object N22) discovered in the first half of July 2016 (period 2016 N).

2016 NN22 has a 670 day orbital period and an eccentric orbit that takes it from 0.97 AU from the Sun (i.e. 97% of the average distance at which the Earth orbits the Sun) to 2.03 AU from the Sun (i.e. 203% of the average distance at which the Earth orbits the Sun, considerably outside orbit of 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 close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in October 2014 and the next predicted in June 2038. 2016 NN22 also has occasional close encounters with the planet Mars, with the last having occured in March 2016.

See also...

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