Download The Outer Planets - Mr. Cramer

The Outer Planets
Gas Giants and Pluto
• The four outer planets – Jupiter, Saturn, Uranus,
and Neptune – are much larger and more massive
than Earth, they do not have solid surfaces
• The four planets are called gas giants
• Pluto is classified as a dwarf planet
• Gas giants are composed of hydrogen and helium,
which is in liquid form
• Have a stronger gravitational force than the
terrestrial planets
• Gravity keeps the gases from escaping, have a thick
atmosphere
• Outer layer is extremely cold because of the
distance from the sun
• Temperature increases within the planets
• All have many moons
• Each is surrounded by a set of ring, a thin disk
of small particles of ice and rock
Jupiter
• Largest and most massive
• 2 ½ times that of all the other planets combined
Jupiter’s Atmosphere
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Thick atmosphere
Mainly hydrogen and helium
Great Red Spot – a storm larger than Earth
Swirling winds blow hundreds of kilometers
per hour (similar to hurricanes)
• No land to weaken the storm
• First observed in the mid-1600s
Jupiter’s Structure
• Dense core of rock or iron
• Thick mantle of liquid hydrogen and helium
surround the core
• Pressure at Jupiter’s core is estimated to be
about 30 million times greater than the
pressure at Earth’s surface
Jupiter’s Moons
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63 plus moons
Four largest moons–
Io – covered with large active volcanoes
Europa – icy crust overs an ocean of liquid water
Ganymede – largest in solar system, larger than
Mercury or Pluto.
• Callisto – icy and covered with craters
• All are larger than Earth’s moon
• Have discovered dozens of addition moons, most
have been found in the last few years due to
improved technology
Saturn
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2nd largest in solar system
Thick atmosphere made up of hydrogen and helium
Contains clouds and storms, not as big as Jupiter
Average density is less than that of water
Saturn’s rings
• The rings are made up of chunks of ice and
rock, each traveling in its own orbit around
Saturn.
• Each ring is divided into many thinner rings
• Rings are broad and thin, like a compact disc
Saturn’s Moons
• The largest is Titan, larger than Mercury
• Discovered in 1665
• Titan has an atmosphere so thick that little
light can pass through it
• Four other moons are over 1,000 kilometers in
diameter
• 47 plus moons
Uranus
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Four times the diameter of Earth
Much smaller than Jupiter and Saturn
Twice as far from the sun as Saturn
Much colder
Looks blue-green because of traces of
methane gas in its atmosphere
• Surrounded by thin, dark, flat rings
Discovery of Uranus
• Discovered in 1781
• First new planet discovered since ancient
times
• Started an era of active solar system study
after discovery
Exploring Uranus
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Voyager 2 sent back images of Uranus
Few clouds
Rotates in about 17 hours
Rotation is tilted at an angle of about 90
degrees from vertical
• Rotates from top to bottom
• Think was hit by an object that knocked it on
its side
Uranus’s Moons
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27 plus moons
Five largest moons have icy, cratered surfaces
Moons have lava flows
Voyager 2 revealed 10 moons never seen
before
Neptune
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Uranus and Neptune look like twins
Similar in size and color
Cold blue planet
Atmosphere contains few clouds
Scientists think Neptune is slowly shrinking,
causing its interior to heat up
• As energy rises to the surface, it produces
clouds and storms in the atmosphere
Discovery of Neptune
• Discovered because of a mathematical
prediction
• 1846 mathematicians calculated the orbit of
an unseen planet (Uranus)
• Then observed the unknown planet in the
predicted area
Exploring Neptune
• 1989 Voyager 2 flew by Neptune
• Photographed the Great Dark Spot about the
size of Earth, probably a giant storm
• Storm didn’t last long, 5 years later it was gone
• Storms seem to come and go in Neptune’s
atmosphere
Neptune’s Moons
• 13 plus moons
• Largest is Triton which has a thin atmosphere
• Region near Triton’s south pole is covered by
nitrogen ice.
Pluto
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Much smaller and denser
Solid surface
Smaller than Earth’s moon
Three known moons
Charon is the largest and half the size of Pluto
Pluto’s Orbit
• Pluto is so far away from the sun that it revolves
around the sun only once every 248 Earth years
• Orbit is elliptical and comes closer to the sun than
Neptune on part of its orbit
• Many icy objects larger and farther out than Pluto
have astronomers creating a new class of objects
called “dwarf planets”
• Dwarf planet, is round and orbits the sun, and has
not cleared out the neighborhood around its orbit.
Questions
1. Compare and Contrast the 4 gas planets.
2. Describe an important characteristic of each
outer planet that helps to distinguish it from
the other outer planets.
3. Why do all the gas giants have thick
atmospheres?
4. What is the Great Red Spot and its
significance?