Wednesday 5 June 2019

Asteroid 2019 KG2 passes the Earth.

Asteroid 2019 KG2 passed by the Earth at a distance of about 1 017 000 km (2.65 times the average distance between the Earth and the Moon, or 0.68% of the distance between the Earth and the Sun), at about 3.10 pm GMT on Thursday 30 May 2019. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2019 KG2 has an estimated equivalent diameter of 12-39 m (i.e. it is estimated that a spherical object with the same volume would be 12-39 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 10 km above the ground, with only fragmentary material reaching the Earth's surface.

The calculated orbit of 2019 KG2. Minor Planet Center.

2019 KG2 was discovered on 27 May 2019 (three 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 2019 KG2 implies that the asteroid was the 55th object (object G2 - in numbering asteroids the letters A-Y, excluding I, are assigned numbers from 1 to 24, so that G2 = (24 x 2) + 7 = 55) discovered in the second half of May 2019 (period 2019 K).

2019 KG2 has an 374 day orbital period and an eccentric orbit tilted at an angle of 19.7° to the plane of the Solar System, which takes it from 0.79 AU from the Sun (i.e. 79% of the the average distance at which the Earth orbits the Sun) to 1.24 AU from the Sun (i.e. 124% of the average distance at which the Earth 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 very common, with the last having occurred in May 2018 and the next predicted in June 2020.

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