Nasa spacecraft discovers tiny moon around asteroid during close flyby

A photo taken by the Lucy spacecraft of asteroid Dinkinesh. Photo / AP

The little asteroid visited by Nasa’s Lucy spacecraft this week had a big surprise for scientists.

It turns out that the asteroid Dinkinesh has a dinky sidekick - a mini-moon.

The discovery was made during Wednesday’s flyby of Dinkinesh, 480 million kilometres away in the main asteroid belt beyond Mars. The spacecraft snapped a picture of the pair when it was about 435 kilometres out.

In data and images beamed back to Earth, the spacecraft confirmed that Dinkinesh is barely 790 metres across. Its closely circling moon is a mere 220 metres in size.

Nasa sent Lucy past Dinkinesh as a rehearsal for the bigger, more mysterious asteroids out near Jupiter. Launched in 2021, the spacecraft will reach the first of these so-called Trojan asteroids in 2027 and explore them for at least six years. The original target list of seven asteroids now stands at 11.

Dinkinesh means “you are marvellous” in the Amharic language of Ethiopia. It’s also the Amharic name for Lucy, the 3.2 million-year-old remains of a human ancestor found in Ethiopia in the 1970s, for which the spacecraft is named.

“Dinkinesh really did live up to its name; this is marvellous,” Southwest Research Institute’s Hal Levison, the lead scientist, said in a statement.