2. Size and Composition of Pluto
1,500 miles in diameter
1/6 the size of Earth
Composed of 60% rock and 40% frozen gases

3. Irregular Orbit of Pluto
Orbit is highly tilted
More elliptical in shape
Crosses over Neptune’s orbit for 20 years of his 248 years orbit

4. The Discovery of the Kuiper Belt
Discovered in 1992 by Jewitt and Luuu
Over 70,000 objects discovered thus far
Some objects rival or surpass Pluto’s size

5. Redefining of a Planet by the IAU
Definition of a planet (2006):
Must orbit the Sun
Must have nearly round shape
Must have cleared its orbit