Friday 24 July 2020

Asteroid 2020 NO passes the Earth.

Asteroid 2020 NO passed by the Earth at a distance of about 782 400 km (20.4 times the average distance between the Earth and the Moon, or 0.52% of the distance between the Earth and the Sun), slightly before 4.30 am GMT on Wednesday 22 July 2020. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2020 NO has an estimated equivalent diameter of 9-28 m (i.e. it is estimated that a spherical object with the same volume would be 9-28 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 33 and 18  km above the ground, with only fragmentary material reaching the Earth's  surface.

The orbit and current position of 2020 NO. The Sky Live 3D Solar System Simulator.

2020 NO was discovered on 11 July 2020 (eleven days before its closest encounter with the Earth) by the University of Hawaii's PANSTARRS telescope. The designation 2020 NO implies that it was the 2914th asteroid (asteroid O - in numbering asteroids the letters A-Y, excluding I, are assigned numbers from 1 to 24, with a number added to the end each time the alphabet is ended, so that A = 1, A1 = 25, A2 = 49, etc., which means that O = 14) discovered in the first half of July 2020 (period 2020 N - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

2020 NO has an 894 day (2.45 year) orbital period and an eccentric orbit tilted at an angle of 2.09° to the plane of the Solar System, which takes it from 0.98 AU from the Sun (i.e. 98% of the the average distance at which the Earth orbits the Sun) to 2.65 AU from the Sun (i.e. 265% of the average distance at which the Earth orbits the Sun, and significantly 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 happen occasionally, with the last thought to have happened in October 2015 and the next predicted in June 2025.The asteroid also sometimes passes close to the planet Mars, with last such encounter having happened in March 1954.

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