Sunday 10 April 2022

Asteroid 2022 GN1 passes the Earth.

Asteroid 2022 GN1 passed by the Earth at velocity of 15.51 km per second and a distance of about 125 600 km (0.33 times the average distance between the Earth and the Moon, or 0.08% of the distance between the Earth and the Sun, about 308 times the distance at which the International Space Station obits, and 35 times as far from the Earth than satellites in geostationary orbits), slightly after 3.00 am GMT on Wednesday 6 March 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 GN1 has an estimated equivalent diameter of 5-17 m (i.e. it is estimated that a spherical object with the same volume would be 5-17 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) between 40 and 25 km above the ground, with only fragmentary material reaching the Earth's surface.

120 second image of 2022 GN2 taken with the Elena Planetwave 17" Telescope at Ceccano in Italy on 5 April 2020. The asteroid is the small point at the centre of the image, indicated by the white arrow, the longer lines are stars, their elongation being caused by the telescope tracking the asteroid over the length of the exposure. Gianluca Masi/Virtual Telescope Project.

2022 GN1 was discovered on 4 April 2022 (two 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 2022 GN1 implies that the asteroid was the 38th object (asteroid N1 - 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 = 26, A2 = 51, etc., which means that N1 = 25 + 13 = 38) discovered in the first half of April 2022 (period 2022 G - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).

The relative positions of 2022 GN1 and the Earth on at 3.00 am on 6 March 2022. JPL Small Body Database.

2022 GN1 is calculated to have a 947 day (2.59 year) orbital period, with an elliptical orbit tilted at an angle of 2.70° to the plain of the Solar System which takes in to 0.78 AU from the Sun (78% of the distance at which the Earth orbits the Sun) and out to 3.00 AU (three times the distance at which the Earth orbits the Sun, or roughly twice 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 GN1 has occasional close encounters with the Earth, with the last thought to have happened in September 1957 and the next predicted in September 2030.

The orbit and current position of 2022 GN1. The Sky Live 3D Solar System Simulator.

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