Asteroid 2020 WG5 passed by the Earth at a distance of about 361 400 km (0.94 times the average distance between the Earth and the Moon, or 0.24% of the distance between the Earth and the Sun), slightly after 2025 am GMT on Thursday 26 November 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 WG5 has an estimated equivalent diameter of 6-18 m (i.e. it is estimated that a spherical object with the same volume would be 6-18 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 24 km above the ground, with only fragmentary material reaching the Earth's surface.
2020 WG5 was discovered on 27 November 2020 (the day after its closest approach to the Earth) by the University of Arizona's Catalina Sky Survey, which is located in the Catalina Mountains north of Tucson. The designation 2020 WG5 implies that it was the 132nd asteroid (object G5 - in numbering asteroids the letters A-Y, 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 G5 implies the 132nd asteroid (G5 = (25 x 5) + 7 = 132) discovered in the second half of November 2020 (period 2020 W - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).
2020 WG5 has a 493 day (1.35 year) orbital period, with an elliptical orbit tilted at an angle of 0.48° to the plain of the Solar System which takes in to 0.91 AU from the Sun (91% of the distance at which the Earth orbits the Sun) and out to 1.52 AU (152% of the distance at which the Earth orbits the Sun, and more than the distance at which the planet Mars 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 Asteroid 2020 WG5 has occasional close encounters with the Earth, with the most recent having happened in June 2020, and the next predicted for Augusr 2042. The asteroid also has occasional close encounters with the planet Mars, with the next predicted in January 2082.
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