Monday 18 January 2016

Asteroid 2016 AH164 passes the Earth.

Asteroid 2016 AH164 passed by the Earth at a distance of 26 660 km (0.08 times the average distance between the Earth and the Moon, or 0.02% of the average distance between the Earth and the Sun; 6660 km above the orbit at which the satellites supporting GPS systems operate), slightly before 3.25 am GMT on Tuesday 12 January 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2016 AH164 has an estimated equivalent diameter of 2-6 m (i.e. it is estimated that a spherical object with the same volume would be 2-6  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 more than 37 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of 2016 AH164JPL Small Body Database.

2016 AH164 was discovered on 13 January 2016 (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 2016 AH164 implies that it was the 4108th asteroid (asteroid H164) discovered in the first half of January 2016 (period 2016 A).

2016 AH164 has a 674 day orbital period and an eccentric orbit tilted at an angle of 0.70° to the plane of the Solar System that takes it from 0.94 AU from the Sun (i.e. 94% of the average distance at which the Earth orbits the Sun) to 2.07 AU from the Sun (i.e. 207% of the average distance at which the Earth orbits the Sun, considerably more than the distance at which Mars orbits). 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 2004 this year and the next predicted in August 2020.
 
See also...
 
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