What Planet Has A Moon That Is More Than Half Its Size?

The planetary status of Pluto is often debated. But if you believe Pluto to be a planet then it is Charon its moon that is nearly half its own size and that has a mass equal to an eighth of the moon. Because of this similarity in sizes Pluto and Charon are often referred to as double planets. Pluto and Charon take the same 6.39 days to rotate and both face the same side of their planetary surface to each other. It is believed that Pluto's moon was formed because of some planetary collision similar to that led to the formation of Earth's moon.

Pluto has two other tiny moons as well. It takes Pluto two hundred and forty seven years to complete one revolution around the sun. None of us will live to see even half of Pluto's revolution round the sun.

The dwarf-planet Pluto's moon Charon is almost 2/3 it's size.

Pluto