New pictures of asteroid 2004 BL86, which passed close by Earth yesterday, have been released by US space agency Nasa.
They show that the asteroid has its own small moon orbiting it.
The asteroid passed by the Earth at a safe distance of 1.2 million km, giving scientists a rare chance to study it 'up close'.
The new data shows that asteroid 2004 BL86 is about 325m across, and its moon is around 70m wide.
Now that it has passed Earth the asteroid will continue on its orbit around the Sun, and it won't come this close again for another 200 years!
The next 'close shave' of a large asteroid is due in 2027: that object is called 1999 AN10 and is just over 1km wide.