dipper@utastro.UUCP (Debbie Byrd) (02/18/86)
This is the anniversary of the discovery of Pluto. More about it -- right after this. February 18 The Discovery of Pluto Around the beginning of this century, the search began for a planet located beyond the orbit of Neptune. Irregularities in the orbit of Neptune sparked the search. It was believed that some large planet must be pulling on Neptune -- causing it to stray somewhat from its otherwise predictable orbit around the sun. Well, many people tried to calculate the orbit of the unknown planet -- most notably Percival Lowell. And finally the new planet was found -- on today's date, in the year 1930 -- by Clyde Tombaugh of the Lowell Observatory outside Flagstaff. The planet was given the name Pluto, for the mythological brother of Neptune -- an appropriate name also since the first two letters are Percival Lowell's initials. But Pluto's discovery introduced more mysteries than it solved. For one thing, Pluto isn't a giant planet, as many people had predicted. Instead, it's extremely small -- smaller than Earth's moon. Some astronomers used to speculate that Pluto was in fact an escaped moon of Neptune -- until Pluto was found to have its own moon -- discovered just a few years ago. What's more, Pluto is so small that it couldn't have caused the deviations in Neptune's orbit -- which is what caused us to look for it in the first place! Today some astronomers are still searching for another undiscovered planet -- an unknown member of the sun's family located beyond the orbit of Pluto. Script by Deborah Byrd. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin