Pluto’s identity crisis hits the classroom

NEW YORK - Pluto was once a planet. Then, a dwarf planet. And as of last week, a plutoid. The fall from grace has teachers, parents and educational publishers struggling to keep up, while kids remain loyal to their favorite, the ninth planet. Underscore planet.

Last week, the International Astronomical Union (IAU) announced Pluto should now be called a "plutoid," two years after the organization voted to demote Pluto to "dwarf planet" status.

Meanwhile, many kids are nearly certain Pluto is still a planet.

"I think it's a planet. But me and my friends, we talk about it sometimes and we go back and forth," said Natalie Browning, 9, sitting in a park in Manhattan with her family. "Right now, I'm not 100 percent. I'm just 75 percent" sure that Pluto is a planet.

Natalie's mom, Bobbie Browning, said, "You've got kids with textbooks saying that Pluto is part of the solar system and a planet, and teachers have to say it isn't [a planet]."

Science teachers and publishers already worked to update their resources to read "dwarf planet." And now, boom, that category is out of favor among astronomers.

"Students who have just learned about the concept of dwarf planets must now be taught the new concept of plutoid," said Janis Milman, who teaches earth science at Thomas Stone High School in Maryland. "This will lead to confusion in the classroom and resistance to learning the new terms, because the students will question, why learn something that might change again in a year or so?"

A cursory survey at a large chain bookstore here revealed three out of four books published in 2006 or later were updated, with Pluto designated as a dwarf planet and the solar system said to include just eight planets.

Chronicles of Pluto
Discovered in 1930 by Clyde W. Tombaugh at Lowell Observatory in Arizona, Pluto was always considered an oddball of sorts, with its tiny size (smaller than some moons) and eccentric orbit.  During its 248-year trek around the sun, Pluto swings from its farthest point from the sun at 49.5 astronomical units (AU) to as close as 29 AU from the sun. One AU is the average distance between the Earth and sun, or about 93 million miles (150 million kilometers).

More than 70 years later, in August 2006, 424 astronomers at an IAU meeting voted to demote Pluto to dwarf planet status. Last week, the IAU Executive Committee reclassified Pluto as a plutoid. The other object in the plutoid club, Eris, is larger and more massive than Pluto.

Astronomers expect to find hundreds of Pluto-sized objects. And so the fate of Pluto will determine how these worlds are classified. For instance, new computer modeling suggests an object up to 70 percent of Earth's mass is lurking beyond Pluto. This "Planet X," if confirmed, would be called a plutoid under the IAU's scheme.

No matter what the scientists say, many kids won't let go.

"It's a planet," said fifth-grader Emily Mitchell, whose mother Laurie agreed, saying, "I grew up learning it was a planet."

"It's the smallest planet," said Liam, a 4-year-old who is "about to be 5." Liam's teacher Rachel Kaplan said, "I was really sad when Pluto was declassified as a planet, because I've studied astrology for a number of years."

Aileen Wilson said her 7-year-old son is interested in Pluto's label. "He's interested in why it was a planet and why it's not a planet anymore."

"I know that it was demoted and it's not a planet. But I don't know what it's called," said Erin Kelly, a pre-school teacher sitting on a park bench with her students in New York.

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