NASA usually has a reassuringly close eye on asteroids that come anywhere near our planet, but one has managed to slip through the net.
An asteroid called 2023 NT1 reached as close as around 62,000 miles from Earth – about a quarter the distance between Earth and the moon – on July 13.
But it wasn’t until two days after its close approach that NASA scientists detected it, because it was coming from the direction of the sun and was obscured by light.
The first reported observation two days later was by ATLAS South Africa, a four-telescope system dedicated to spotting hazardous asteroids.
At up to 200 feet (60 metres) across, 2023 NT1 could be larger than the asteroid that caused Meteor Crater in Arizona, said amateur astronomer Tony Dunn on Twitter.
The historic impact crater near Flagstaff, around 3,900 feet in diameter, is thought to have been caused by a rock that hit Earth around 50,000 years ago.