Published Online: September 6, 2006
Published in Print: September 6, 2006, as Schools Adjusting to Pluto’s Fall From Planetar

Schools Adjusting to Pluto’s Fall From Planetary Grace

Its change in status provides opportunity for lessons about the nature of science.

Tiny, frigid, and remote, Pluto has endured relentless astronomical skepticism since its discovery more than 70 years ago. And now, the shadowy brown orb has suffered the supreme indignity of losing its very status as a planet, to be replaced with a decidedly less-awesome descriptor: dwarf planet.

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The International Astronomical Union’s recent downgrading of Pluto with that label capped years of scholarly debate about whether it was truly a planet, or a celestial object, or even a dormant comet.

Pluto’s reclassification, approved last month, will change the way that scientists and stargazers think and talk about the solar system—and it is likely to have a similar effect on school science lessons, where Pluto’s planetary standing, until now, has been relatively secure.

Officials in the multibillion-dollar school publishing industry, meanwhile, say it will take at least a few years to revise textbooks to reflect Pluto’s new status. States are also likely to be forced to review their science assessments and standards to correct any now out-of-date references to the ex-planet.

But those complications aside, educators and scientists say they see an immediate opportunity for teachers to use Pluto’s recent demotion to highlight and reinforce lessons for students about astronomy—and the nature of science itself.

“Instead of being a static body of knowledge, science is constantly changing—even for things that we might think of as unchanging—‘What is a planet?’ ” said Shirley M. Malcom, who directs the education and human-resources division of the American Association for the Advancement of Science, in Washington. “Our understanding is shifting here. Humans try to impose some understanding on the world they see.”

Planet or Not?

Until it was relabeled, Pluto was known as the smallest, most distant, and perhaps the most mysterious planet in the solar system.

It wasn’t discovered until 1930—and only then with the help of mathematical calculations to pinpoint its location. It was named for the ancient god of the Roman underworld, as well as for the initials of astronomer Percival Lowell, who was instrumental in finding it. Pluto is less than one-fifth the size of Earth in diameter, and nearly 40 times as far from the sun, which helps explain its estimated temperature of minus-375 degrees Fahrenheit.

Budding astronomers are encouraged to gaze skyward for on-the-spot lessons, but faraway Pluto can be seen only through a telescope. For years, students have associated Pluto with the Walt Disney character, or remembered it as the bookend of familiar classroom mnemonic devices for what were then the solar system’s nine planets, such as “My Very Excellent Mother Just Served Us Nine Pizzas.

Most science teachers are adept at using news events to reinforce their lessons, and Pluto’s reclassification offers just such an opportunity, said Rich Hogen, who taught elementary school for more than 30 years, most recently in the 32,000-student Chandler, Ariz., district.

“It’s a great point of discussion,” he said last week. “How many of them would like Pluto to be a planet—and why? How many of them wouldn’t?”

Mr. Hogen, who recently retired but still volunteers in another district, said teachers sometimes struggle to present lessons on the solar system because the material is so abstract. But they also benefit from students’ innate curiosity about space—and from the permanent, nightly visual aid beaming overhead.

He uses lessons on the planets to build nonscientific skills, too. One year on Pluto is equal to 248 years on Earth; he asks students to write essays, imagining life on that distant world.

Most students are introduced to the solar system in the elementary grades, then learn about more specific geological, chemical, and atmospheric concepts in middle school, AAAS officials say. In high school, they typically delve deeper into the physics and chemistry of the solar system, and use mathematics to better understand its vast size.

The debate over Pluto’s status gives teachers an important opportunity to explain how scientists classify different aspects of the natural world as a way to order and explain it, education experts say.

“Pluto isn’t any different than it was a year ago, or 100 years ago, or 250 years ago,” said Ted Willard, a senior program associate who works on education issues for the AAAS. “How we categorize it has changed.”

Textbooks and Tests

The International Astronomical Union, a professional society with headquarters in Paris, originally considered expanding the list of planets from nine to 12, allowing Pluto to remain in that category. But on Aug. 24, it instead voted to trim the list of planets to eight, excluding Pluto, which was reclassified as a dwarf planet.

Pluto met two of the union’s conditions for a planet: It orbits the sun, and it is big enough for gravity to crush it into a round ball. But it failed the third test: the ability to clear objects out of its orbital path.

It will probably take one to three years before the majority of science textbooks at various grade levels are updated to reflect Pluto’s revised status, said Jay Diskey, the Washington-based executive director of the Association of American Publishers’ school division. Those companies are making supplemental materials and online resources available to schools, until then.

“The vast majority of students,” Mr. Diskey predicted, “will hear about Pluto’s demotion in a fairly timely manner.”

How soon publishers make changes is likely to depend on the demands of crucial markets such as California and Texas, which approve textbooks for local districts. California could ask publishers to make revisions in November, the state’s last science textbook-adoption cycle for six years. Texas will not adopt new science textbooks until 2010, so teachers are likely to use supplementary materials until then, said Debbie Graves Ratcliffe, a spokeswoman for the Texas Education Agency.

Texas will also change items on its state science assessment to reflect Pluto’s new status, she said. Other states are likely to make similar modifications to their tests and the language of their state science standards, said an official with the Council of Chief State School Officers, in Washington.

The shift from a nine- to an eight-planet solar system is not likely to faze science teachers, Ms. Ratcliffe suggested.

“Science changes so much from year to year,” she said. Teachers are “used to dealing with changes, and pulling newspaper articles and other materials to use in their classrooms.”

Vol. 26, Issue 02, Page 10

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