"The Pluto Files:" a planetary identity crisis

Perhaps if it had not been thought to be the wealthy astronomer Percival Lowell's long-sought Planet X when a 24-year-old farmhand and amateur astronomer, Clyde W. Tombaugh, spotted it in 1930 after a heroic search.

Perhaps if it had not been named by an 11-year-old British schoolgirl.

Perhaps if Walt Disney had not given the same name to Mickey Mouse's pet canine.

Perhaps then people would have more readily accepted the decision of the International Astronomical Union (IAU) in August 2006 to remove Pluto from the pantheon of major planets.

But in fact, outside of the scientific community, and to a lesser extent within it, the "demotion" of Pluto set off a storm of protest.

Neil deGrasse Tyson was not surprised. As director of the Hayden Planetarium in New York City's Museum of Natural History, he was at the center of a similar brouhaha five years earlier, which he relates in "The Pluto Files: The Rise and Fall of America's Favorite Planet" (Norton, 194 pp., $23.95).

For much of the late 1990s, Tyson's major task was assuring the accuracy, accessibility and time-

liness of the science behind the exhibits in the stunning Rose Center for Earth and Space in New York City. This included the treatment of the bodies of the solar system on the walkway leading to the Rose Center's focal point, the Hayden Sphere.

Tyson and his colleagues, recognizing that the definition of "planet" had become fluid, finessed it.

"We looked across the solar system and asked ourselves what physical features about planets and other objects could be taken together and discussed as common properties or phenomena."

So in one area along the walkway, visitors would encounter models of the terrestrial planets, Mercury, Venus, Earth and Mars. In another, they would find the gas giants, Jupiter, Saturn, Uranus and Neptune. Pluto would appear elsewhere, in the Planet Zone in the Hall in the Universe.

For 11 months after the Rose Center opened, that decision seemed surprisingly uncontroversial. Then, on Jan. 22, 2001, came a New York Times front page story headlined, "Pluto's Not a Planet? Only in New York."

The story's full text covered the decades of steadily growing doubt about Pluto's planethood, but the glare of the headline washed out all nuance.

"It's not easy being a public enemy," Tyson writes with good humor. "Schoolchildren and adults alike branded me as a thoughtless, heartless Pluto hater."

"The Pluto Files" is an eclectic delight. Readers will laugh at the collection of song lyrics and cartoons inspired by the great Pluto-versy. They will smile at the photocopied letters from elementary-school children wise beyond their years.

They will chuckle with the author at photographs and e-mails that show his good-natured yet intellectually serious tussling with colleagues.

In the end, they will appreciate that neither the definition of the term nor the number of planets in the solar system is what matters. And, planet or not, it will be the focus of earthly attention when NASA's New Horizons mission reaches it in 2015.

More than two years after Pluto's "demotion," the "Ask Dr. Fred" question, "Why Isn't Pluto a Planet Anymore?" remains by far the most visited page of physicist and children's author Fred Bortz's Web site (www.fredbortz.com).