Scientists say the Earth has captured a second moon

The Earth has captured a new moon and it's been pulled into orbit, the Minor Planet Centre says.

But it won't be there permanently - it's only "temporarily bound to Earth", the centre said in a statement on its website.

There's only been one asteroid known to have orbited Earth before this one. The latest temporarily captured object has been labelled '2020 CD3'.

"No evidence of perturbations due to solar radiation pressure is seen, and no link to a known artificial object is found," the Minor Planet Centre says.

"Further observations and dynamical studies are strongly encouraged."

Astronomer Kacper Wierzchos said on Twitter the object was captured on February 15.

"My Catalina Sky Survey teammate Teddy Pruyne and I found a 20th magnitude object.

Wierzchos wrote that it entered the Earth's orbit three years ago.

"It's a big deal as out of 1 million known asteroids, this is just the second asteroid known to Orbit Earth."

He said the other asteroid known to have orbited Earth was the '2006 RH120', also discovered by the Catalina Sky Survey.