This is a drawing of Pluto and its moon Charon.
Click on image for full size
Image courtesy of NASA/JPL. This image is in the public domain.
Pluto & Charon, a binary planet
Of all the planets and moons in the solar system, Pluto and Charon are the two which resemble each other the most closely. They are almost the same size, and they are very close together. They are so close together that they orbit the center of mass between them, and the center of mass goes around the sun. (In general, each planet with its moons orbits the center of mass between them, but in every other case the center of mass is the center of the planet, so the moon goes around the planet. Not so in the case of Pluto and Charon.)
Pluto and Charon are so close that they may even share an atmosphere. Methane molecules may be drawn off Pluto and recondense on Charon.
The other planet and moon in the solar system which could be a binary planet are the Earth and the Moon. As in the case of the Earth and the Moon, the origin of such a system is hard to explain. The explanation which seems best is that some large object struck Pluto (and the Earth) and tore Charon (and the Moon) from the crust of the planet. In the case of the Moon, the Moon seems to be made of material very much like the Earth's crust and not like the Earth's more metallic interior. Likewise Charon may be made of more icy material which resembles Pluto's surface, rather than the more rocky interior of Pluto.
You might also be interested in:
It may seem hard to believe that Pluto could have an atmosphere because it is so cold at 39 AU, where Pluto resides, but it does. Because there are times when Pluto is closer to the sun than is Neptune
...more
Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); known moons. Charon, the largest by far, was discovered in 1978 by the American astronomer James Christy.
...moreCharon is by far the largest of Pluto's // Call the moon count function defined in the document head print_moon_count('pluto'); known moons. Charon was discovered by the American astronomer James Christy
...more
Of all the planets and moons in the solar system, Pluto and Charon are the two which resemble each other the most closely. They are almost the same size, and they are very close together. They are so
...more
Pluto is so far away, and has never been explored. Questions to answer about Pluto include the following: What are the geologic features of the surface. (pictures of the surface) If there are bare spots,
...more
No one knows whether or not Pluto has a magnetosphere. Scientists were very surprised to find that Jupiter's icy moon Ganymede had a magnetosphere because it is hard to explain how an icy body can develop
...morePluto is a frigid ball of ice and rock that orbits far from the Sun on the frozen fringes of our Solar System. Considered a planet, though a rather odd one, from its discovery in 1930 until 2006, it was
...more
