The Outer Planets

The Inner Planets to Scale 3,031 mi 7,521 mi 7,926 mi 4,222 mi 5.4 g/cm3 5.2 g/cm3 5.5 g/cm3 3.9 g/cm^3

The Outer Planets to Scale 88,700 mi 75,000 mi 31,700 mi 30,200 mi 1.3 g/cm3 0.7 g/cm3 1.3 g/cm3 1.6 g/cm3

Outer Planet Similarities All are tens of thousands of miles across –Much larger than the inner planets All are made of gas - hydrogen and helium –No rocky surface like the inner planets All are not very dense (b/c made of gas) Why do the outer planets share these similarities? Why don’t the outer planets have more in common with the inner planets?

Jupiter Largest planet Colorful cloud bands Rapid rotation (9h50m) -250°F at cloud tops Great Red Spot

Hurricane-like storm, fueled by heat inside of Jupiter Large enough to cover 3 Earths Discovered by Galileo nearly 400 years ago –Why can it last so long compared with hurricanes on the Earth?

Saturn Least dense planet - Would float on water! Bulges because of rapid rotation (10h30m) Large, broad rings

Saturn’s Rings Made of countless small chunks of ice and rock –Why don’t the chunks combine to form a moon? –Why doesn’t Earth have rings? 170,000 miles wide, <1 mile thick

Uranus Discovered by accident (1781) Blue-green color from methane in its atmosphere -350°F at cloud tops Almost featureless; little weather –Why might Uranus lack distinctive weather patterns?

Uranus’ Axis Axis tilted 98° from its orbit Orbits Sun every 84y How would these factors affect its seasons?

What’s Wrong with Uranus? Following its discovery, astronomers calculated its orbit Uranus mysteriously speeded up, then slowed down –Why might Uranus have deviated from its calculated orbit?

Neptune Discovered at its predicted position (1846) Blue color from methane -370°F at cloud tops Great Dark Spot in 1989, but not 1994 –How is this different from the Great Red Spot? –Why is its weather different from Uranus? Jupiter?

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