Pluto's demotion provides teaching moment

Educators emphasize changeability of science

Tuesday, August 29, 2006

By JANE CARLSON

The Register-Mail

Norm Gross always thought Pluto was a little different.

The smallest, outermost planet in the solar system wasn't like the terrestrial planets of Mercury, Venus, Earth and Mars.

But it wasn't like the gas giants of Jupiter, Saturn, Uranus and Neptune, either.

So in 12 years of teaching astronomy at Carl Sandburg College, Gross has simply classified Pluto as "other."

Now that the International Astronomical Union has demoted Pluto to "dwarf planet," Gross and teachers everywhere are revising their lesson plans and incorporating the new definition of a planet into the curriculum.

"I see what has happened as good science," Gross said. "We finally have a definition of what a planet is and we've needed that for a long time."

Pluto was stripped of its planetary status Aug. 24 at the IAU meeting in Prague, Czech Republic, after delegates decided its eccentric orbit and icy configuration put it in different category than the eight remaining planets circling the sun.

But Gross said there is an important lesson about science in general to be learned from Pluto's fate.

"Science is not cast in stone," Gross told the nine students in his Physical Universe class Monday morning at CSC. "It is always subject to change."

Pluto was discovered in 1930 by astronomer Clyde Tombaugh. Since then, students across the world have been taught that there are nine planets in the solar system.

"It seems weird that it's not a planet anymore," said CSC student Jessica Brownlee of Galesburg. "It's a change in the foundation of what we've been taught all these years."

Brownlee, like many of her classmates, grew up learning songs and mnemonics to help remember the names of the planets and their distances from the sun.

Gross, too, has a bit of a sentimental attachment to the entity formerly known as a planet.

"Pluto will always be a planet to me," he said. "But for young kids, this doesn't mean a whole lot. Pluto will always be a dwarf planet to them."

Late last week at Galesburg High School, teacher and science department chair Dave Baxter took Pluto down from a display of the solar system on the wall of his classroom.

"I never thought I would have to do that," said Baxter, who doesn't believe calling Pluto a dwarf planet will diminish its notoriety. "In fact, it will just heighten it."

Baxter won't be teaching astronomy until the spring semester, but he said students and other teachers have been stopping by to talk about Pluto since school started last week. He said he sees this as "golden opportunity" for debate and discussion and not as a reason to rush to replace textbooks.

Ross Johnson, eighth-grade science teacher at Churchill Junior High, said the demotion of Pluto will make the study of the solar system stand out in students' minds.

"It's exciting because it shows that science is constantly changing," Johnson said.

At the Galesburg Public Library, books with titles such as "The Nine Planets" and "Postcards from Pluto: A Tour of the Solar System" are among the dozens of books on the "Planets and Stars" shelf in the children's department that are now technically outdated.

"We will have to replace all of the books as soon as new ones come out," said Karen Marple, head of the children's department.

She said she updates non-fiction sections regularly to keep up with changing information, but the news that Pluto is no longer a planet took her by surprise.

"I thought we would be safe with the planets," Marple said.