1. Pluto
A Dwarf Planet

2. General Facts About Pluto
Pluto orbits beyond the orbit of Neptune (usually)
It is much smaller than any of the official planets and now classified as a "dwarf planet“
In Roman mythology, Pluto (Greek: Hades) is the god of the underworld
Pluto was discovered in 1930 by a fortunate accident
we now know that there are a very large number of small objects in the Kuiper Belt beyond the orbit of Neptune, some roughly the same size as Pluto

3. More General Facts About Pluto
Pluto has a satellite, Charon.
Charon was discovered in 1978
In late 2005, two additional tiny moons were found to orbit Pluto (known as Nix and Hydra). They are estimated to be between 60 and 200 km in diameter
Pluto's orbit is highly eccentric. At times it is closer to the Sun than Neptune (as it was from January 1979 thru February )
Pluto rotates in the opposite direction from most of the other planets
Pluto's equator is at almost right angles to the plane of its orbit

4. Comparison of Earth and Pluto
orbit: 149,597,871 km (1 AU) from the Sun (average)
diameter: 12,713 km
mass: x 1024 kg
Revolution: days
Rotation: 24 hours
Rotational axis: tipped 23.5 degrees
orbit: 5,913,520,000 km (39.5 AU) from the Sun (average)
diameter: 2274 km
mass: x 1024 kg
Revolution: Earth years
Rotation: days
Rotational axis: tipped 122 degrees

5. Comparison of Earth and Pluto
Pluto is smaller than seven of the solar system's moons (the Moon, Io, Europa, Ganymede, Calistoga, Titan and Triton)

6. Missions to Pluto Pluto has not yet been visited by a spacecraft
Even the Hubble Space Telescope can resolve only the largest features on its surface
A spacecraft called New Horizons was launched in January If all goes well it should reach Pluto in 2015

7. New Horizons Mission
Since Pluto is so far from Earth, little was known about the dwarf planet's size or surface conditions until 2015, when NASA's New Horizons space probe made a close flyby of Pluto.

8. New Horizons Mission What did New Horizons find?
Pluto has a diameter of 1,473 miles (2,370 km)
A variety of surface features, including mountains that reach as high as 11,000 feet (3,500 meters), comparable to the Rocky Mountains on Earth.
Pluto's surface is also covered in an abundance of methane ice (New Horizons scientists observed significant differences in the way the ice reflects light across the dwarf planet's surface.)
a large heart-shaped region known unofficially as Tombaugh Reggio (after Clyde Tombaugh)

9. New Horizon Photos of Pluto

10. Why Is It No Longer Considered a Planet?
Due to additional objects being discovered including Eris (a dwarf planet in the Kuiper Belt) which is 27% more massive than Pluto, the IAU (International Astronomical Union) reclassified Pluto and the other objects as dwarf planets
Kuiper Belt objects are comet-like in composition