Planets

See the planets of the solar system and learn a bit about each one. There are now only eight planets, because the International Astronomical Union voted Aug. 24, 2006, to classify Pluto as a "dwarf planet."

Pluto is no longer one of the planets. In August 2006, its classification was changed to "dwarf planet."

Talk About It

The new definition of a planet is a celestial body that: a) orbits the sun; b) is massive enough that its own gravity pulls it into a nearly round shape; c) is dominant enough to clear away objects in its neighborhood.

International Astronomical Union Site

Get notified via e-mail about notable sky-watching events, such as eclipses and meteor showers.

Alert Me

Just enter your ZIP code and this new interactive sky chart displays the night sky for your area. Find out when you can view different planets and more. (Free Java software is required to view the chart.)
Sky Chart Instructions
Stargazing Sky Chart

Get night sky guides, plus news, photos and videos.

Kuiper Belt Objects NASA / AP

These are some of the largest objects in the Kuiper Belt, a vast collection of asteroids, comets -- and a few dwarf planets -- with orbits beyond Neptune. Pluto and 2003 UB313 (aka Xena) were designated dwarf planets by astronomers, Aug. 24, 2006. The other objects shown here are now called "small solar-system bodies," as are all other Kuiper Belt objects.