Pluto - Research Article from Macmillan Science Library: Space Sciences

This encyclopedia article consists of approximately 5 pages of information about Pluto.
This section contains 1,234 words
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Pluto

Pluto is the only planet in the solar system still unvisited by a spacecraft. Its status as the only planet in our Sun's family still studied purely by telescope is unique—and frustrating—to planetary scientists trying to uncover its secrets.

Pluto's Strange Orbit

American astronomer Clyde Tombaugh discovered Pluto in 1930. Despite astronomers' best efforts, Pluto's faintness and star-like appearance allowed the planet to keep most of its secrets. For twenty-five years, we could only refine our knowledge of its strange orbit, finding it on old photographs and taking new ones. Pluto's orbit is more eccentric and more tilted (inclined) than any other planet, taking 248.8 years to make one trip around the Sun. At perihelion (closest approach, which last occurred in 1996), it is only 60 percent as far from the Sun as at aphelion (farthest approach). So at perihelion, Pluto is closer to the Sun than Neptune...

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This section contains 1,234 words
(approx. 5 pages at 300 words per page)
Buy the Pluto Encyclopedia Article
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Macmillan Science Library: Space Sciences
Pluto from Macmillan Science Library: Space Sciences. Copyright © 2001-2006 by Macmillan Reference USA, an imprint of the Gale Group. All rights reserved.