"Well it was quite a bit of a surprise. It turns out that 1998 QE2 is a binary asteroid."
The discovery that the asteroid has its own moon came on Wednesday when astronomers noticed the asteroid had a smaller asteroid, or satellite, orbiting it.
The radar imagery was taken using a 230 foot Deep Space Network antenna in California.
A closer look showed the asteroid has a white dot orbiting it, this, NASA says, is it's satellite.
The asteroid and its smaller moon were set to pass Earth from a safe distance of 3.6 million miles on Friday.
