Asteroid 2024 EF passed by the Earth at a distance of about 58 340 km (15% of the average distance between the Earth and the Moon or 0.04% of the distance between the Earth and the Sun), with a velocity of about 8.64 km per second, at about 7.00 am GMT on Monday 4 March 2024. There was no danger of the asteroid hitting us, though were it to do so it would not have presented a major threat. 2024 EF has an estimated equivalent diameter of 3-9 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 30 km above the ground, with only fragmentary material reaching the Earth's surface.
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2024 EF was discovered on 2 March 2024 (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 2024 EF implies that the asteroid was the sixth object (asteroid F - 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 F = 6) discovered in the first half of March 2024 (period 2024 E - the year being split into 24 half-months represented by the letters A-Y, with I being excluded).
2024 EF is calculated to have a 534 day (1.46 year) orbital period, with an elliptical orbit tilted at an angle of 1.29° to the plain of the Solar System which takes in to 0.94 AU from the Sun (94% of the distance at which the Earth orbits the Sun) and out to 1.63 AU (1.63 times the distance at which the Earth orbits the Sun, somewhat more 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).
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This means that 2024 EF has regular close encounters with the Earth, with the last calculated to have happened in June 2021, and the next predicted for September this year (2024).
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