Asteroid 2022 YO1 passed by the Earth distance of about 26 900 km (7% of the the average distance between the Earth and the Moon, 0.02% of the distance between the Earth and the Sun, or 66 times the distance at which the International Space Station orbits), with a velocity of about 15,4 km per second, at about 6.40 pm GMT on Sunday 17 December 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 YO1 has an estimated equivalent diameter of 2-6 m (i.e. it is estimated that a spherical object with the same volume would be 2-6 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 47 km above the ground, with only fragmentary material reaching the Earth's surface.
2022 YO1 was discovered on 17 December 2022 (the day of 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 2022 YO1 implies that it was the 39th asteroid (object O1 - 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 O1 = 14 + 25 = 39) discovered in the second half of December 2022 (period 2022 Y - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).
2022 YO1 has a 731 day (2.0 year) orbital period, with an elliptical orbit tilted at an angle of 13.6° to the plain of the Solar System which takes in to 0.80 AU from the Sun (80% of the distance at which the Earth orbits the Sun) and out to 2.36 AU (236% 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 2022 YO1 has occasional close encounters with the Earth, with the last having happened in April 2009 next predicted for December 2024.
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