Pluto Demoted

Solar system shrinks to eight planets

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The artist's concept shows the Pluto system. Pluto is the large disk at center, right. (Photo: NASA, ESA and G. Bacon (STScI))

My Very Educated Mother Just Served Us…Noodles? That could be the new way school children everywhere will be taught to remember the planets of the solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, and Neptune.

So what happened to Pluto? The educated mother used to serve Nine Pizzas for Neptune and Pluto. But now that an international group of astronomers have demoted the ninth planet, students everywhere are left with noodles. Some critics of the move say they are left with Nothing!

"Pluto is dead," said Mike Brown, a researcher from Caltech University in California. He was following the group’s decision-making process with interest. Brown is known for his discovery of what could have been considered a 10th planet. That object, called 2003 UB313, is actually bigger than Pluto.

Group Decision

New guidelines for planets were adopted this week by the General Assembly of the 2006 International Astronomical Union (IAU). According to these guidelines, Pluto is now a “dwarf planet,” after 76 years as a planet. Mercury, Venus, Earth, Mars, Saturn, Jupiter, Uranus, and Neptune are now called “classic” planets.

The new rules state that a celestial body must have “cleared the neighborhood around its orbit” to be considered a classic. Pluto’s orbit overlaps with Neptune’s, making it the odd planet out.

But Pluto is not alone. More than a dozen former asteroids could soon be named dwarf planets. Those include Ceres and Brown’s discovery, 2003 UB313.

“More dwarf planets are expected to be announced by the IAU in the coming months and years,” said a spokesperson from the group.

While the decision is not earth-shattering for astronomers, it means a lot to school kids around the world. Textbooks will have to be rewritten and science projects updated.

“It’s not affecting me personally, but it’s kind of depressing,” said Nathan Kahn, 13, of New York. “I’ve been brought up thinking of Pluto as the ninth planet.” The eighth grader built a mobile of the solar system when he was in the third grade. “I guess now they are going to have to redo all the text books.”

Pluto was discovered in 1930 by Clyde Tombaugh. The young astronomer was just 24 when he made the historic sighting while working at Lowell Observatory in Flagstaff, Arizona.

Critical Thinking Question

Read today's news story, and then answer the following question.

		Pluto Demoted Do you think Pluto should be considered a planet? Explain.

Join a discussion of this question on our bulletin board.

RELATED WEB SITES

Solar System Exploration: Pluto

Learn all about Pluto at this informative site.

NASA: Kids

Check out this site for games, activities, and stories about space.

Karen Fanning is a contributing writer for Scholastic News Online.

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