Saturday 1 August 2020

Asteroid 2020 OW5 passes the Earth.

Asteroid 2020 OW5 passed by the Earth at a distance of about 924 500 km (2.41 times the average distance between the Earth and the Moon, or 0.62% of the distance between the Earth and the Sun), slightly after 6.05 pm GMT on Tuesday 25 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 OW5 has an estimated equivalent diameter of 11-35 m (i.e. it is estimated that a spherical object with the same volume would be 11-35 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 30 and 15  km above the ground, with only fragmentary material reaching the Earth's  surface.

The orbit and current position of 2020 OW5. The Sky Live 3D Solar System Simulator.

2020 OW5 was discovered on 29 Juy 2020 (four days after 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 2020 OW implies that the asteroid was the 142nd object (asteroid W5 - 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 W5 = (24 x 5) + 22 = 142) discovered in the second half of July 2020 (period 2020 O).

2020 OW5 has a 963 day (2.64 year) orbital period, with an elliptical orbit tilted at an angle of 0.85° to the plain of the Solar System which takes in to 1.00 AU from the Sun (the distance at which the Earth orbits the Sun) and out to 2.82 AU (2.82% of the distance at which the Earth orbits the sun and almost twice as far from the Sun as 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). 2020 OW5 has had one previous close encounter with the Earth, in September 1991.

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