The Outer Planets

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The Outer Planets

• Chap 16, Sec 4

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Chap 16 Sec 4 Essential Questions

1. What characteristics do the gas giants have in
   common?
2. What characteristics distinguish each of the
   outer planets?

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The Gas Giants
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The Gas Giants

• The four outer planets
• Jupiter
• Saturn
• Uranus
• Neptune
• Much larger more massive than Earth
• Do not have solid surfaces
• All are composed mainly of hydrogen helium
• Their gravitational force is much greater than
  Earths because of their massive size
• They have thick atmospheres
• A lot of the hydrogen helium inside the planets
  is liquid because of enormous pressure
• Outer layers of the planets are cold because of
  their distance from the sun, but temperatures
  increase inside the planets
• All have many moons
• All have rings
• A ring is a thin disk of small particles of ice
  and rock

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Jupiter
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Jupiter

• The largest most massive planet
• Its mass is about 2 ½ times all other planets
  combined
• Atmosphere
• Thick atmosphere of mainly hydrogen helium
• The Great Red Spot a giant storm larger than
  Earth. Swirling winds blow hundreds of miles an
  hour, similar to a hurricane, but it has lasted
  for 350 years and doesnt appear to be weakening

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Jupiter

• Structure
• A dense core of rock and iron at the center
• The core is surrounded by a thick mantle of
  liquid hydrogen helium
• Pressure at Jupiters core may be 30 million
  times greater than the pressure at Earths
  surface
• Extreme pressure is caused by its thick atmosphere

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Jupiters Moons

• Remember Galileo discovered the largest four
• Many more have been discovered as technology
  improved latest count is more than 63
• The four largest are all very different from each
  other and are all larger than our Moon

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Jupiters Largest Moons

• Io its surface is covered with large, active
  volcanoes. Sulfur gives it an unusual color.
• Europa it has an icy crust and scientists
  suspect it has an ocean of liquid water
  underneath the ice
• Ganymede the largest moon in the solar system
  is larger than Mercury or Pluto
• Callisto has an icy, cratered surface

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Io
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Ganymede
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Europa
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Callisto
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Saturn
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Saturn

• The second-largest planet
• Has a thick atmosphere of hydrogen helium
• Atmosphere has thick clouds and storms though
  not as spectacular as those on Jupiter
• The least dense planet (less dense than water)
• The Voyager probes provided lots of information
  about Saturn

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Saturns Rings

• Saturn has the most spectacular rings of any
  planet
• The rings are broad and thin like a CD
• The rings are made of chunks of ice and rock,
  each traveling in its own orbit around Saturn

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Saturns Moons

• Saturn is currently known to have more than 60
  moons
• The largest is Titan
• It has a very thick atmosphere (so thick that
  light can hardly pass through)
• There are four other moons that are larger than
  1,000 kilometers in diameter

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Two views of Titan
From Far Away
Very Close Up with special Lens
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Uranus
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Uranus

• It is about four times the diameter of Earth, but
  much smaller than Jupiter and Saturn
• It is twice as far from the sun as Saturn, so it
  is much colder
• Has a unique blue-green color because of methane
  gas in its atmosphere
• Its rings are thin, flat, and much darker than
  Saturns
• It was the first planet discovered since ancient
  times
• Discovered in 1781 by Willam Herschel in England

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Unique Features of Uranus

• In the 1980s (200 years after being discovered)
  Voyager 2 arrived at Uranus and sent back
  close-up pictures
• It has few clouds, but astronomers calculated it
  rotated in about 17 hours
• Uranus is tilted on its side
• It rotated top to bottom instead of side to side
  like other planets (and its rings and moons
  rotate around its tilted axis)
• Scientists think it was hit by an object billions
  of years ago that knocked it on its side

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Uranuss Moons

• Uranus has at least 27 moons
• Voyager 2 discovered the five largest moons have
  icy, cratered surfaces and lava flows

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Neptune
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Neptune

• Neptune is similar in size and color to Uranus
• It is a blue color because of methane in its
  atmosphere
• Because it is so far from the sun, it is very
  cold
• It has clouds and storms in its atmosphere
• Scientists think the clouds and storms are
  happening because the planet is slowly shrinking
  and causing the interior to heat up

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Discovering Neptune

• Neptune was discovered by mathematics
  astronomers noticed Uranuss orbit wasnt the
  exact path it should be and predicted an unseen
  planet was disturbing Uranuss orbit
• By 1846 scientists had calculated the orbit of
  the unseen planet soon after, Neptune was
  identified

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Flying by Neptune

• In 1989 Voyager 2 flew by Neptune and
  photographed the Great Dark Spot (a storm about
  the size of Earth)
• Storms come and go on Neptune which tells us it
  has an active atmosphere

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Neptunes Moons

• Neptune has at least 13 moons
• The largest is Triton
• It has a thin atmosphere
• Its south pole is covered in nitrogen ice

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Pluto

• Pluto is not a gas giant
• It is much smaller and denser than the outer
  planets and has a solid surface
• Pluto is smaller than our Moon
• Pluto is so far from the sun that it takes 240
  Earth years to revolve around the sun once
• Its orbit is very elliptical and it crosses
  inside Neptunes orbit for part of its revolution
• Moons
• Pluto has at least three. The largest is Charon
  and is more than half as big as Pluto

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Dwarf Planets

• Dwarf planets are round and orbits the sun, like
  a planet, but it has not cleared out the
  neighborhood around its orbit
• Dwarf planet classification was created in 2006
  when an object larger than Pluto and farther from
  the sun was discovered
• At that time Pluto was reclassified as a dwarf
  planet and there are two others

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Video
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Essential Questions - Answered

• What characteristics do the gas giants have in
  common?
• No solid surface
• Thick atmosphere made mostly of hydrogen helium
• A set of rings
• Very Large massive
• Rotates quickly, revolves slowly

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• 2. What characteristics distinguish each of the
  outer planets?
• Jupiter largest most massive planet, Great
  Red Spot, most moons (63)
• Saturn second largest planets, best rings,
  least dense planet
• Uranus blue-green color, rotates on its side
• Neptune blue color, lots of storms
• Pluto solid, rocky surface no longer a planet