When the International Astronomical Union (IAU) reclassified Pluto as a dwarf planet in August, people worldwide responded with strong opinions both positive and negative. The “demotion” of Pluto from ninth planet to dwarf evoked comments ranging from the humorous (“I'm sure the Plutonians are very upset,” quipped one blogger) to the disconcerted (Patricia Tombaugh, widow of Pluto discoverer Clyde Tombaugh, told the Associated Press that the IAU’s decision was “disappointing in a way, and confusing”) to the supportive, as exemplified by Bill Nye “the Science Guy” in an ABC News video. Pluto’s change in status actually benefits science, he explains, because it gets people to ponder “what it means to live on a planet, to live in the cosmos and be part of the universe, and what it means to try and understand these points of light in the night sky.”

For a change, people were thinking about and talking about science.

Many news stories published at the end of August highlighted the benefits of Pluto’s reclassification for science educators. NSTA President-Elect John Whitsett told CNN.com (”Pluto's Demotion Not a Cause for Classroom Panic,” August 27): "It's a chance to start looking at more than just the nine planets. What do we mean by a comet? What do we mean by a dwarf planet?" In science classes, he continued, “students are going to be asking questions, and I've always found that the best time to teach is when kids are asking questions. Anything that gets kids engaged and thinking about science has got to be a good thing."

In his story for the Tulsa World (“Where Did Pluto Go?”; August 25), Tom Droege interviewed Stephanie Butler, a teacher at Clyde Boyd Middle School in Sand Springs, Oklahoma, who said, “It's actually a cool teaching point for me because it shows that science is continuously changing. It's also good for teaching my students that it's okay to be wrong because you can learn from it."

Astronomer Mike Brown of the California Institute of Technology—who in July discovered a new object, 2003 UB313, which he nicknamed Xena—thought that he had found the 10th planet because Xena is much larger than Pluto. But according to the IAU’s new definition, Xena is only a dwarf planet. Interviewed by Robert Roy Britt, senior science writer for Space.com, Brown expressed optimism about the reclassification’s consequences for science education: "For teaching this is a very interesting moment. I think you can describe science much better now." On his own website, Brown elaborated on that comment. ”Culture and science have always meant something different when they use the word ‘planet,’ and with this new scientific definition so clearly far removed from what the rest of the world thinks a planet is, there will no longer be any need to confuse the scientific word with the cultural one.”

Many teachers have expressed regret that they will no longer be able to use longstanding mnemonics—memory devices, like “My Very Educated Mother Just Served Us Nine Pizzas”—to help students remember the names of the planets. But Brian Marsden, director of IAU’s Minor Planet Center, told Alexis Akwagyiram of BBC News (“Farewell, Pluto,” August 2, 2005) that “school textbooks concentrate too much on the idea that Pluto is the ninth planet. Teaching should stress that there are hundreds of thousands of much smaller objects. Knowing a mnemonic and naming the planets is not science." For those who disagree with Marsden, Nick Greene, writing in the Space/Astronomy section of the website About, invites website visitors to devise a new mnemonic.

While Pluto’s entry into the dwarf planet family has strongly affected teachers and scientists, its repercussions for textbook publishers and vendors of science materials have been even more drastic. In her August 24 story for CNET News.com, Caroline McCarthy writes that

“no matter how quickly a publisher can roll out new editions of its Earth science, astronomy, or general science texts, tight state educational budgets complicate the situation. A state's department of education will typically order new course materials every five or six years, said David Hakensen, vice president of public relations at Pearson Education. Since Pearson has no plans to offer physical updates to its existing texts—such as stickers or supplemental pages—the states that ordered new science textbooks for the impending academic year most likely won't be getting new, eight-planet versions for another half decade."

McCarthy noted that textbook publishers are “leaning on the internet to deal with the Pluto demotion through online lesson plans and course supplements” and that publishers of classroom magazines are reporting the latest news about Pluto to help teachers supplement outdated textbooks. Teachers are accustomed to turning to these sources, observes George D. Nelson in “An Evolutionary Framework for Instructional Materials.” “Many teachers,” said Nelson, “have assembled and developed collections of activities, demonstrations, and laboratories to supplement or replace the text.”

In his August 24 article “The Lighter Side of Pluto,” MSNBC.com’s science editor, Alan Boyle, asked Carl Benoit, editorial director for Illinois-based Learning Resources, which sells space science teaching aids, how he thought teachers should view the Pluto reclassification. "I think it'd be a good idea to keep Pluto around and explain that this has been a planet for 76 years,” said Benoit. "It becomes an educational process, to explain to kids why it was a planet, and now why it's not. … That's the kind of critical thinking that kids need to be doing when they do science."

Some websites teachers can use for teaching about Pluto are NASA’s Space Place sites Hail King of the Ice Dwarfs! and Big Planets, Little Planets, Dwarf Planets, Big Moons, Little Moons! and the Pluto and the Dwarf Planets site from the Smithsonian’s National Air and Space Museum.