Asteroid 2023 BU in 'extraordinarily close' call with Earth

Although 3,600km away, the passing of the minibus-sized space rock is deemed a near miss

Asteroid 2023 BU passed Earth on Friday, in one of the closest approaches on record. PA
Beta V.1.0 - Powered by automated translation

An asteroid has passed closer to Earth than some satellites.

Asteroid 2023 BU passed over the very bottom of South America overnight, after being spotted by an amateur astronomer in Crimea last weekend.

Nasa's Scout impact hazard assessment system quickly determined that the asteroid would miss Earth, the US space agency said.

"Despite the very few observations, it was nonetheless able to predict that the asteroid would make an extraordinarily close approach with Earth," said Nasa's Davide Farnocchia, who helped develop Scout.

"In fact, this is one of the closest approaches by a known near-Earth object ever recorded."

Although 3,600km away, the passing of the minibus-sized space rock is deemed a close call. Only three others have passed as close since records began.

Even if it had looked set to connect with the planet, the relatively small size of the asteroid (3.5-8.5 metres) means it would have burned up in the Earth's atmosphere before it connected, creating a fireball which would have been visible from the surface.

"Before encountering Earth, the asteroid's orbit around the Sun was roughly circular, approximating Earth's orbit, taking 359 days to complete its orbit about the Sun," Nasa said.

"After its encounter, the asteroid's orbit will be more elongated, moving it out to about halfway between Earth's and Mars' orbits at its furthest point from the Sun. The asteroid will then complete one orbit every 425 days."

The asteroid's passing was livestreamed online.

"Today's asteroid flyby is one of the closest ever recorded, but our Planetary Defence experts have been tracking the asteroid and know it's not a threat to Earth," Nasa Administrator Bill Nelson said on Twitter.

Updated: January 27, 2023, 9:52 AM