The Outer Planets
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Transcript of The Outer Planets
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• Over 50 are now known orbiting beyond
Neptune, some beyond Pluto• Pluto is probably just the biggest of these
objects (not really a planet?)• Several dozen have periods similar to
Pluto’s - 250 years - and have been dubbed “plutinos.”