Pluto

Pluto

Not too many people are familiar with the only American who discovered a planet, although it's no secret.. Pluto was discovered in 1930 by Clyde Tombaugh after an exhaustive search. The late Dr. Tombaugh would rankle at the suggestion that his discovery was mere accident. He spent a lot of hard, long, cold hours looking for that planet. He was destined to find it!

Pluto is so different from the other eight planets. Is Pluto, then, really a planet? Despite some recent discussion, and the recent resolution of the International Astronomical Union, Pluto is, in the opinion of some professional astronomers, including myself, still the ninth planet and one of the larger distant, cold group of iceballs known as the Kuiper objects. Perhaps we need a little perspective on this.

Here are some of the essential facts about Pluto:

Radius 1150 km which is about one sixth the size of Earth
Rotation 6 days 9 hours
Revolution 246 years to orbit the Sun
Semi major axis 39.4 A.U.
Atmosphere Generally none, unless it is close enough to the Sun to sublimate the surface ice.
Surface Features Uncertain dark and light spots, which can be seen in this animation from Hubble Space Telescope data.
Moons or rings The moon Charon is half as big as Pluto. Two smaller moons, named Nix and Hydra, have been recently discovered. And Pluto might yet be found to have a ring.
Space ProbesNo spacecraft has yet visited Pluto, but New Horizons is on its way. Here is a page that presents the current status of that spacecraft.

Try this site for more information on Pluto!

Let's Watch the NOVA episode on the story of Pluto.

Watch the full episode. See more NOVA.

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Updated December 1, 2011