The Gas Giants...and Pluto The Outer Planets The Gas Giants...and Pluto

Gas Giants – p. 562 First four outer planets do not have solid surfaces. Jupiter Saturn Uranus Neptune They are very large and have strong gravity that pull the gases in, creating a thick atmosphere. Gas giants have atmopsheres of mostly hydrogen and helium (mostly liquid, not gas). Outer layers are very cold because they are so far from the sun. All four planets have many moons and a set of rings made of particles of ice and rock.

Jupiter Jupiter is the most massive planet (about 2.5 times the mass of all other planets combined). It’s atmosphere is mostly hydrogen and helium like the other gas giants, but it has a giant red spot – a storm larger than the planet Earth. Structure of Jupiter: Core: dense with rock and iron Mantle: liquid hydrogen and helium surrounding core

Jupiter’s Moon Jupiter has more than 63 moons Four largest were discovered by Galileo: Io Europa Ganymede (largest moon in the solar system-bigger than pluto and Mercury) Callisto

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Saturn Saturn is the second largest planet in the solar system Atmosphere is similar to the other gas giants (hydrogen and helium) and also contains clouds and storms. Saturn’s average density is less than the density of water.

Saturn’s Rings Rings are made of rock and ice, each in their own orbit around the planet. Saturn’s rings are the most spectacular of any planet Appear as a few rings from Earth. Each of these obvious rings is made of many thinner, smaller rings

Saturn’s Moon Saturn has more than 47 moons Titan is the largest. Larger than the planet Mercury So large that it has its own thick atmosphere

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Uranus Uranus is 4 times the size of Earth, but still smaller than Jupiter and Saturn. Twice as far from the sun as Saturn, so it is very cold. Appears blue-green because of the methane gas in its atmosphere. Uranus has thin flat rings that are much darker than Saturn’s.

Uranus’s tilt Uranus has a unique tilt of its axis of rotation 90° to the side

Uranus’s Moon Uranus has more than 27 moons Largest moons have icy, cratered surfaces. Moons have lava flow.

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Neptune Discovered when astronomers predicted another planet was affecting the orbit of Uranus. Regions of clouds and storms come and go on Neptune. Once had a great dark spot the size of Earth that has disappeared.

Neptune’s Moons Neptune has over 17 moons. Largest it Triton. Has a thin atmosphere Has ice at its south pole region

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Pluto Pluto is solid and much smaller than the other outer planets (smaller than Earth’s moon). Charon is Pluto’s moon. More than half the size of pluto Some believe Charon and Pluto are twin planets If Pluto had been discovered now, it would not have been called a planet. Too similar to rock, ice, and dust that orbit the sun past Neptune.

Pluto