Scientists have discovered two more small moons orbiting Pluto which makes three in all. The newly found satellites orbit about 27,000 miles (44,000 kilometers) from Pluto, more than twice as far as existing moon Charon. They were found with Hubble.

"It's almost like a mini-solar system," said Hal Weaver of the Johns Hopkins Applied Physics Laboratory. "How can something about 70 percent the size of Earth's moon have all these satellites? .... We're going to have to explain that."

As of now, Pluto is the only Kuiper Belt object known to have more than one moon. "Our result suggests that other bodies in the Kuiper Belt may have more than one moon as well," said team co-leader Alan Stern.