U.S. astronomer Clyde Tombaugh discovered Pluto, then considered to be the ninth planet in our solar system, in 1930.

While conducting a systematic search at Lowell Observatory in Flagstaff, AZ, for a predicted planet beyond Neptune, Clyde Tombaugh discovered Pluto. Pluto was named after the Roman god of the underworld, who was able to make himself invisible. The name "Pluto" was suggested by 11-year-old Venetia Burney. 

Science NetLinks 
Learn about the geology, composition and orbits of the planets in our solar system, including Pluto, in the Science NetLinks lesson Exploring the Solar System (6-8).  

Students gain a better understanding of the size of Pluto and the other planets in our solar system by using the interactive tool, Planet Size Comparison (6-8).

ARTSEDGE 
In Planets in Balance (5-8), students research a planet's composition, weather, atmosphere and satellites, and then create a mobile of the planet and its satellites.

Illuminations 
Students use measurement, mathematical computations and the known speed of the Space Shuttle to determine the amount of time it would take to travel to each planet in the solar system in Travel in the Solar System (6-8).

Smithsonian's History Explorer
Focused around Maria's Comet, a work of children's literature about a young girl who longs to study the stars, Exploring the Sky (K-4), includes links to hands-on activities and a list of recommended readings for further exploration.