Yep! Pluto has five moons, but the biggest of them is Charon. Charon is about 12% of Pluto’s mass, which is comparatively huge for a moon–our Moon is about 1.2% of Earth’s mass. Because of this, Pluto and Charon are often thought of as a binary system. Here’s the gif again for this who didn’t see, made up of actual images taken by New Horizons:
When we say that one object is orbiting another, it’s a bit of a simplification because the two objects are actually orbiting around a common centre of mass, called a barycenter. This is because every object exerts a gravitational pull on the other one, no matter how small. Think about the Earth orbiting the Sun: the Earth is so small compared to Sun’s huge mass (0.000003%) that their common centre of mass actually lies inside the Sun, about 450km from to its core (but considering that the radius is the Sun is about 700,000 km, 450 km is not much).
So, while the Earth swings around in an huge orbit with a radius of 150 million km due to the Sun’s pull, the Sun just wobbles a tiny bit due to Earth’s pull–maybe a metre.
Pluto and Charon are different, though. Because Charon is decent chunk of Pluto’s mass, their barycenter is outside both objects–and they both orbit around this common point, which is super obvious. Here’s a model of it:
When New Horizon arrives later in the year, we’ll see this planetary dance up close.