1. Clyde Tombaugh discovered Pluto on February 18, 1930 at the Lowell Observatory in Flagstaff, Arizona.

2. The name was actually suggested by an 11year old English school girl named Venetia Burney.

3. Pluto was all the rage in 1930 leading animator Walt Disney to choose that as the name for Mickey Mouse's dog, who was introduced the following year.

4. In keeping with the tradition of other planets named after Roman gods, Pluto is the god of the underworld and is able to render himself invisible.

5. Pluto is more than 5.9 billion kilometers (3.7 billion miles) from Earth.

6. Pluto is so far from the Sun that the sun's light is about 1905 times dimmer than it appears on Earth.

7. Its diameter is 2400 kilometers (1485 miles) compared to our 12,756 k (7926 m)

8. Pluto's orbit is elliptical, tilted 17 degrees off the approximate orbit of all the other planets in our solar system.

9. From January 1979 to February 1999 Pluto was actually closer to the Sun than Neptune, the eighth planet.

10. Astronomer James Christy discovered Pluto's moon Charon on June 22, 1978. It is named after the mythical boatman who ferried souls across the river Styx to be judged by the underworld god Pluto.

11. Charon is the largest moon in our solar system, in relation to its planet. At 1184 k (736 miles) it is almost exactly half the size of Pluto.

12. Pluto is thought to be about 4.5 billion years old.

13. A year on Pluto, the time it takes to orbit the Sun, is 248 Earth years!

14. A day on Pluto, the time it takes to rotate on its axis. is 6 Earth days, 9 hours, 17 minutes.

15. The surface temperature of Pluto on average is -218 degrees Celsius ( -370 Fahrenheit).

16. Pluto's surface is a mixture of rocky and icy material.

17. Pluto's atmosphere is a thin layer of methane gas.

18. Pluto's surface gravity is 1/15 that of earth.

19. In October 2005, NASA's Hubble Space Telescope sent back the first pictures of two previously unknown moons around Pluto, two to three times further from the planet than Charon. They are currently unnamed pending confirmation.

20. On January 19, 2006 the first probe to Pluto, called New Horizons, was launched with some of Dr. Tombaugh's ashes onboard. It will take nearly ten years to reach the planet and is expected to vastly further our understanding of our mysterious and wondrous neighbor.

(source: "Pluto: The Ninth Planet" by Michael D. Cole, Enslow Publishers, Inc., 2002)