"The Pluto Files: The Rise and Fall of America's Favorite Planet" (Norton. 194 pages, $23.95), By Neil deGrasse Tyson: If there is an advocacy group for little guys in the universe, it must have been asleep on Aug. 24, 2006. On that fateful day, the International Astronomical Union demoted Pluto to a "dwarf planet," tossing it out of the nine-member family of planets in the solar system. The reason? It did not meet one of the new, IAU criteria that a full-fledged planet must have an orbit clear of celestial debris. Pluto's, unfortunately, is cluttered with such debris.

The decision caused consternation around the Earth, but the IAU wasn't the first group that gave the poor thing a body slam. Several years earlier, the science committee designing the American Museum of Natural History's $230 million Frederick Phineas and Sandra Priest Rose Center for Earth and Space decided its planet exhibit would not include Pluto. The round object is unlike any of the other planets in size, orbit and composition. Therefore, the committee decided, they should treat it as just another ice-and-rock ball that resides 4 billion miles away in a region called the Kuiper Belt.

After the center opened in February 2000, The New York Times called this grievous omission to public attention in an article headlined "Pluto's Not a Planet? Only in New York." As a result, Neil deGrasse Tyson who headed the committee was branded, in his words, a "thoughtless, heartless Pluto hater."

Now, the astrophysicist and director of the center's Hayden Planetarium, has written a highly entertaining and enlightening book about the whole brouhaha: "The Pluto Files; The Rise and Fall of America's Favorite Planet."

It offers fascinating scientific tidbits about Pluto, discovered in 1930 and named for the Roman god of the underworld. But what makes this book a charmer is its collection of poems, cartoons, quotes, lyrics, even state legislature resolutions that cropped up after Pluto's demotion in an outpouring of love and sympathy.

A third-grader's letter with a drawing of a crying Pluto tells Tyson in no uncertain terms, "Pluto is a Planet!!!!!!!" A pro-Pluto planetary scientist is shown in a photo jokingly attempting to choke Tyson. An amateur astronomer who wrote a biography of Pluto's discoverer, Clyde Tombaugh, is quoted as saying, "Tyson is so far off base with Pluto, it's like he's in a different universe." The Little Prince, the fictitious boy who lives on a "planet," is seen exchanging blows with the IAU. Yoda of "Star Wars" also proclaims that, in his book, Pluto is a planet.

One cartoon shows a scientist picking flower petals, mumbling "Pluto's a planet, no, it's not ..." This succinctly points out astronomy's unique problem to which Pluto seems to have fallen victim. With so many unknowns in the universe, classification of a cosmic object could change overnight as new discoveries are made. At one point in history, it was thought there were as many as 18 planets.

Tyson, who comes through as an open-minded man who has never lost a sense of humor during his ordeal as the "public enemy" of Pluto supporters, says he made a pilgrimage to Disney World and explained to Pluto, the animated cartoon dog, why he had to be demoted. He says Mickey Mouse's pet accepted the situation graciously, and they became fast pals.

Meanwhile, the IAU bestowed on Pluto a consolation prize of sorts. Rather than being just another minor planet, it is now designated as the standard for a whole new category of dwarf planets called "plutoids."

Is Pluto happy now? Or is it hoping that scientists who disagree with the IAU will be able to restore it to full planethood? At the very end of the book, Pluto's cartoon image is seen uttering a few colorful words. In effect, it says, "Who cares!"