A massive asteroid currently flying past the Earth has its own moon, Nasa has said.
Asteroid 1998 QE2 is about 2.7 kilometres in diameter - about the same size as nine ocean liners.
It's currently on a fly past the Earth - though luckily it's not straying too close, in apocalypse terms, remaining about 5.8 million kilometres away, or 15 times farther than the Moon.
But Nasa said that the fly past isn't just a lucky miss for us, but a good opportunity to study asteroids ahead of a potential series of missions to explore, capture and eventually land on one.
Using the Deep Space Network antenna at Goldstone, California, it's produced the first detailed radio images of the rock. And as it turns out, it isn't alone.
Orbiting the asteroid is a miniature moon, Nasa said, which is about 600 metres wide.
Above: Asteroid 1998 QE2 and its 'mini Moon'
Nasa explains that about 16% of asteroids larger than 200 metres have their own satellites, but it's still pretty amazing to see one so close to Earth.
Nasa will study the rock(s) until about 9 June, when it will start its long journey around the Solar System until it returns to Earth in about 200 years.