The Planetary Society

• Pluto: The Discovery of a Planet
• Hubble Measures the Size of the “10th Planet”

• Much ado about Pluto
• Kuiper Belt

CalTech

• The Discovery of Sedna
• The Eight Planets

BBC

• Pluto loses status as a planet (with diagram of the new solar system)

Johns Hopkins University Applied Physics Lab

• New Horizons Mission Timeline

The launch of the New Horizons spacecraft, which will arrive at Pluto in 2015. (photo credit: NASA/KSC)