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The Outer Planets. Uranus, Neptune and Pluto. Uranus. About 4 times diameter of Earth 3 billion km (1-3/4 billion miles) from Sun 84 Years to Circle Sun Rotates in 16 hours Five large satellites (500-1500 km), ten smaller ones Nine narrow rings. Uranus. Uranus from Voyager.
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The Outer Planets Uranus, Neptune and Pluto
Uranus • About 4 times diameter of Earth • 3 billion km (1-3/4 billion miles) from Sun • 84 Years to Circle Sun • Rotates in 16 hours • Five large satellites (500-1500 km), ten smaller ones • Nine narrow rings
Neptune • About 4 times diameter of Earth- a bit smaller than Uranus • 4.5 billion km (2.8 billion miles) from Sun • 165 Years to Circle Sun • Rotates in 18 hours • One large satellite (2700 km), seven smaller ones • Four narrow rings
Pluto • At 2300 km, Pluto is the smallest planet • Has most elliptical orbit: ranges from 4.4 to 7.4 billion km from Sun (2.8-4.5 billion miles) • Actually crosses orbit of Neptune; closer to Sun than Neptune until 2009 • Orbits in 248 years, 1.5 times Neptune • Because of orbital tilt and resonance, cannot collide with Neptune
Pluto and Charon • Pluto’s moon Charon is almost half as big as Pluto (1100 km) • Orbits only 20,000 km away • Pluto and Charon always keep same face to each other (rotation locked) • Pluto rotates, and Charon revolves, in 6.4 days
Plutinos and the Kuiper Belt • The Kuiper Belt is an outer ice asteroid belt, probably the source of most comets • Hundreds are now known orbiting beyond Neptune, some beyond Pluto • Pluto is just the biggest of these objects and not really a planet • Several dozen have periods similar to Pluto’s - 250 years - and have been dubbed “plutinos.”