CONTENTS WHAT IS A DWARF PLANET 4 THE KUIPER BELT 8 PLUTO 10 ERIS 14 HAUMEA 18 MAKEMAKE 22 CERES 24 NEW FRONTIERS OF EXPLORATION 28 GLOSSARY 30 FOR MORE INFORMATION 31 INDEX 32
4 WHAT IS A DWARF PLANET In 1930 an American astronomer named Clyde Tombaugh noticed something unusual while looking through a tele scope He thought it was a new planet and other scientists agreed The scientists named it Pluto It was considered the smallest planet in the solar system until 2006 In 2006 a group of astrono mers decided that the definition of planet did not apply to Pluto It is now considered a dwarf planet Like planets dwarf planets are large roundish objects that orbit or travel Clyde Tombaugh took this photograph of Pluto shown with an arrow in 1930
Pluto and Other Dwarf Planets
The reclassification of Pluto introduced the new category of dwarf planets to our solar system.
