An artist's conception of Pluto, for the Pluto Fast Flyby Mission.
Click on image for full size
Image courtesy of NASA/JPL. This image is in the public domain.
Pluto 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 officially stripped of its status as our Solar System's 9th planet by the International Astronomical Union in August 2006.
Pluto is now officially classified as a dwarf planet. It is one of the largest members of a class of icy spheres known as Kuiper Belt Objects. It has
known moons; one of which, Charon, is very large - almost as big as Pluto itself!
The surface of Pluto appears to be composed of a mixture of ice and rock, while its interior is probably similar to that of other icy moons in the solar system.
Surprisingly, Pluto does have an atmosphere which is continuously produced and lost while Pluto is within Neptune's orbit. No one knows yet if Pluto has a magnetosphere or not! Maybe we will find out when
NASA's New Horizon mission, which launched in 2006, makes it to Pluto in 2015!
In the Roman pantheon, Pluto was the god of the underworld, and the husband of the beautiful but ill-fated Persephone.
Shop Windows to the Universe Science Store!
Learn about Earth and space science, and have fun while doing it! The games
section of our online store
includes a climate change card game
and the Traveling Nitrogen game
You might also be interested in:
Do you know what a planet is? Guess what... astronomers are not quite sure what a planet is! Mercury, Venus, Earth, and Mars are the planets closest to the Sun. They are definitely all planets. They are...more
Pluto has been officially demoted from its status as a planet. The International Astronomical Union (IAU), at a meeting in August 2006, voted on their first "official" definition of a planet....more
Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); moons. One of the moons is very big. The big moon is name Charon. The other two moons are small. They don't...more
Charon is a moon of Pluto. Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); moons. Charon is much bigger than Pluto's other moons. James Christy discovered...more
The diagram to the left shows what the inside of Pluto may look like. Pluto is mostly made of ice, with a small core of some rocky material buried inside. If the interior is warm enough, the inside of...more
It may seem hard to believe that Pluto could have an atmosphere because it is so cold, but it does. Because there are times when Pluto is closer to the sun than is Neptune (making it the 8th planet for...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...more