This book was written in 1994, when Pluto was considered a bona fide planet. In 2006 it was officially downgraded by the International Astronomical Union and classified as a “dwarf planet.” Such are the tides of fortune in the realm of science. But once again this oddity of the solar system has become the center of controversy, as some scientists still think it should be considered a planet.

This author will refrain from taking a stand on the issue. Whatever its status, Pluto’s discovery remains an interesting story, told here in its original form in which Pluto is unabashedly referred to as a planet.



Pluto has been called "an oddball little planet," "the misfit of the solar system," and "an elusive outcast." Library shelves weigh heavy with books about the other planets, but the section on Pluto is slim.

While not as intriguing as Mars, nor as photogenic as Saturn, the ninth planet holds an important place in the history of astronomy. The events leading up to its discovery involved the triumph of theory over brute observation, years of fruitless searching, controversy in the astronomical community, and a bit of fantastic luck.

Most of what we know about Pluto has been learned in the last twenty years. It remains the only planet not visited by one of the many probes sent out to reveal the secrets of the solar system. We have no soil samples or close-up photographs of Pluto, and we receive no weather reports beamed back by a robotic lander.

Perhaps it's not worth the bother. And yet, Pluto lies on what we consider the edge of the solar system. Today, it's a neglected little oddity in a too distant orbit. Someday, it may be a busy spaceport, gateway to the stars, and rich with tourist dollars. Unless there's another planet beyond Pluto.

This book concerns the discovery of Pluto, with side trips along the way to embellish the story with details, biographies, facts, and a little physics. First, a look at the planet itself.

A Pluto Primer

Table of Contents