Friday 25 March 2016

Asteroid 2016 EN156 passes the Earth.

Asteroid 2016 EN156 passed by the Earth at a distance of 601 800 km (1.57 times the average distance between the Earth and the Moon, or 0.40% of the average distance between the Earth and the Sun), slightly before 6.25 am GMT on Saturday 19 March 2016. There was no danger of the asteroid hitting us, though had it done so it would have presented only a minor threat. 2016 EN156 has an estimated equivalent diameter of 5-16 m (i.e. it is estimated that a spherical object with the same volume would be 5-16 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 between 40 km and 25 km above the ground, with only fragmentary material reaching the Earth's surface.

 The calculated orbit of  2016 EN156JPL Small Body Database.

2016 EN156 was discovered on 13 March 2016 (six days before its closest approach to the Earth) by the University of Hawaii's PANSTARRS telescope on Mount Haleakala on Maui. The designation 2016 EN156 implies that it was the 3913th asteroid (asteroid N156) discovered in the first half of March 2016 (period 2016 E).


2016 EN156 has a 545 day orbital period and an eccentric orbit tilted at an angle of 3.75° to the plane of the Solar System that takes it from 0.91 AU from the Sun (i.e. 91% of the average distance at which the Earth orbits the Sun) to 1.70 AU from the Sun (i.e. 170% of the average distance at which the Earth orbits the Sun, more than the distance at which 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 extremely common, with the last having occurred in August 2013 and the next predicted in February 2019. 2015 EN156 also has occasional close encounters with the planet Mars, with the last calculated to have happened in April 1994 and next predicted in July 2022.
 
See also...
 
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