Generous sponsorship of Windows to the Universe is provided by the Hewlett Foundation, the American Geological Institute, the American Geophysical Union, the National Science Foundation, NASA, NCAR, and the CISM and CMMAP projects. NASA CMMAP AGU CISM NCAR Hewlett AGI NSF
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

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.

News Flash!
Please take our short survey and let us know what you think of our new website design!
The American Geophysical Union has become a Founding Partner of the Windows to the Universe Project!
Free 2009 Earth Science Kits on Climate Change available for Windows to the Universe Educator Members - Join today!
Up to five free telescopes available to Windows to the Universe Educator Members - Join today!

You might also be interested in:

What is a planet?

Do you know what a planet is? If so, you are doing better than professional astronomers! Right now astronomers aren't quite sure how to define a planet. Maybe you've heard that some astronomers think Pluto...more

Pluto demoted - no longer a Planet!

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

The Moons of Pluto

Pluto has // Call the moon count function defined in the document head print_moon_count('pluto'); moons. One of the moons is very large. The large moon is named Charon. The other two moons are fairly small....more

Charon - Pluto's biggest moon

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 larger than Pluto's other moons. James Christy discovered...more

Pluto's Interior

The diagram to the left shows a cutaway of the possible interior structure of Pluto. The composition of Pluto is mostly ice, therefore there is probably a small core of some rocky material buried inside,...more

A Look at Pluto's Atmosphere

It may seem hard to believe that Pluto could have an atmosphere because it is so cold at 39 AU, where Pluto is found, but it does. Because there are times when Pluto is closer to the sun than is Neptune...more

A Look at Pluto's possible Magnetosphere

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

Dwarf Planets

In 2006 the International Astronomical Union (IAU) approved a new classification scheme for planets and smaller objects in our Solar System. Their scheme includes three classes of objects: "small solar...more

Shop Windows to the Universe

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!

Please log in

Username:

Password:

Become a member