Saturday 6 August 2022

Asteroid 2022 OJ5 passes the Earth.

Asteroid 2022 OJ5 passed by the Earth at velocity of about 9.41 km per second and a distance of about 4 06 900 km (1.06 times the average distance between the Earth and the Moon, or 0.27% of the distance between the Earth and the Sun), slightly before 3.00 am GMT on Monday 1 August 2022. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a significant threat. 2022 OJ5 has an estimated equivalent diameter of 3-10 m (i.e. it is estimated that a spherical object with the same volume would be 3-9 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) more than 32 km above the ground, with only fragmentary material reaching the Earth's surface.

The relative positions of 2022 OJ5 and the Earth on at 2.00 am on Monday 1 August 2022. JPL Small Body Database.

2022 OJ5 was first detected on 16 February 2021 (16 days before its closest approach to the Earth), by the University of Hawaii's PANSTARRS2 telescope. The designation 2022 OJ5 implies that it was the 134th asteroid (asteroid J5 - in numbering asteroids the letters A-Z, excluding I, are assigned numbers from 1 to 25, 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 J5 = (25 x 5) + 9 = 134) discovered in the second half of July 2022 (period 2022 O; the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The orbit and current position of 2022 OJ5. The Sky Live 3D Solar System Simulator.

2022 OJ5 is calculated to have a 410 day (1.12 year) orbital period, with an elliptical orbit tilted at an angle of 6.43° to the plain of the Solar System which takes in to 0.75 AU from the Sun (75% of the distance at which the Earth orbits the Sun, and slightly outside the orbit of the planet Venus) and out to 1.40 AU (1.40 times the distance at which the Earth orbits the Sun, and slightly less than the distance at which the planet Mars orbits). 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 2022 OJ5 has regular close encounters with the Earth, with the last thought to have happened in February 2014, and the next predicted for May next year (2023).

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