Asteroid 2020 RK1 passes the Earth.

Asteroid 2020 RK1 passed by the Earth at a distance of about 418 100 km (1.09 times the average distance between the Earth and the Moon, or 0.28% of the distance between the Earth and the Sun), slightly before 1.50 am GMT on Friday 4 September 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 RK1 has an estimated equivalent diameter of 15-48 m (i.e. it is estimated that a spherical object with the same volume would be 15-48 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 25 and 10 km above the ground, with only fragmentary material reaching the Earth's  surface.

 

The orbit and current position of 2020 RK1. The Sky Live 3D Solar System Simulator.

2020 RK1 was discovered on 8 September 2020 (four days after its closest approach to the Earth), by he 0.5-m Asteroid Terrestrial-Impact Last Alert System telescope on Mauna Loa in Hawaii. The designation 2020 RK1 implies that it was the 34th asteroid (asteroid K1 - 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 K1 = 24 + 10 = 34) discovered in the first half of September 2020 (period 2020 R - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

2020 RK1 has a 1052 day (2.88 year) orbital period, with an elliptical orbit tilted at an angle of 3.36° to the plain of the Solar System which takes in to 0.89 AU from the Sun (89% of the distance at which the Earth orbits the Sun) and out to 3.16 AU (316% of the distance at which the Earth orbits the Sun, and more than twice the distance at which the planet Mars orbits the Sun). This means that close encounters between the asteroid and Earth are fairly common, with the last thought to have happened in October 2017 and the next predicted in September 2066. 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 RK1 also has occasional close encounters with the planet Mar, which is next expected to come close to in October this year (2020).

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