The Gas Giant Planets

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Transcript The Gas Giant Planets

The Gas Giant Planets
Chapter 29 Section 3
The Gas Planets
• The interiors of the gas giant planets are composed of
fluids, either gaseous or liquid, and possibly small, solid
• They are composed primarily of lightweight elements such
as hydrogen,
helium, carbon,
nitrogen, and
oxygen, and they
are very cold
at their surfaces.
• The gas giants
have many
satellites as well
as ring systems,
and they are all
very large.
• Jupiter is the largest planet,
making up 70% of all planetary
matter in our solar system, and
the 5th planet from the Sun.
• Jupiter has a banded
appearance as a result of flow
patterns in its atmosphere.
• Jupiter has 4 major satellites in
addition to at least 12 smaller
• Jupiter has been explored by
several United States space
probes which detected volcanic
activity on Jupiter’s closest major
moon, Io.
Jupiter’s Atmosphere
– Jupiter has a low density, 1326 kg/m3, for its
huge size because it is composed of lightweight
– Hydrogen and helium make up the majority of
Jupiter’s atmospheric gas.
– Below the liquid hydrogen, there is a layer of
liquid metallic hydrogen.
– Liquid metallic hydrogen is a form of hydrogen
that has properties of both a liquid and a metal,
which can exist only under conditions of very high
– Electric currents flow within the layer of liquid
metallic hydrogen and generate Jupiter’s
magnetic field.
– At less than 10 hours, Jupiter has the shortest
day in the solar system.
– Jupiter’s Great Red Spot is a storm that has
been rotating around Jupiter for more than
300 yrs.
Jupiter’s Moons and Rings
– Jupiter’s 4 largest moons, Io,
Europa, Ganymede, and Callisto,
are called Galilean satellites.
Jupiter has 16 moons.
– Io has been heated by Jupiter’s
gravitational force to the point of
becoming almost completely molten
inside and undergoes constant
volcanic eruptions.
– Astronomers hypothesize that
Europa has a subsurface ocean
of liquid water.
– Jupiter, like the other 3 gas giant
planets, has rings.
• Saturn is the 6th planet from the Sun and the 2ndlargest planet in the solar system.
• In 2004, the US Cassini mission, launched in 1997,
become the 5th probe to visit the planet.
• It will also release a probe into the atmosphere of
Titan, Saturn’s largest moon, to explore surface
conditions there.
Saturn’s Atmosphere
– Saturn is not quite as large as
Jupiter and has an average
density that is lower than that of
– Saturn rotates rapidly for its
size and has flowing belts and
– Saturn’s atmosphere is
dominated by hydrogen
and helium but it also
includes ammonia ice.
– The internal structure of Saturn
is most likely fluid throughout
with a small, solid core.
– Saturn’s strong magnetic field is
aligned with its rotational axis,
which is unusual among the
Saturn’s Moons and Rings
– Saturn’s ring system has much broader and brighter rings than those of the
other gas giant planets.
– There are 7 major rings composed of narrower rings, called ringlets, and
many open gaps.
– The rings are less than 200 m thick, and are aligned
with Saturn’s equatorial plane.
– The ring particles are probably debris left over when
a moon was destroyed either by a collision or
Saturn’s gravity.
– The 18 known satellites of Saturn include the giant
Titan, 7 intermediate-sized moons, and a number of
small moons.
– Titan is larger than Earth’s moon, and its
atmosphere is made of nitrogen and
• The 7th planet from the Sun, Uranus, was discovered
accidentally in 1781.
• Two of Uranus’s larger moons, Titania and Oberon, were
discovered in 1787.
• Uranus has at least 18 moons and 10 rings.
• In 1986, the United States Voyager 2 mission visited Uranus.
Uranus’s Atmosphere
– Uranus is 4 times as large and 15
times as massive as Earth and
has a blue, velvety appearance.
– Uranus’s atmosphere is
composed of helium and
hydrogen and methane gas and
has no distinct belts or zones.
– Its internal structure is
completely fluid except for a
small, solid core and it has a
strong magnetic field.
– The rotational axis of Uranus is
tipped over so far that the north pole
almost lies in its orbital plane.
– Uranus’s atmosphere keeps the
planet at a temperature of 58 K
Uranus’s Moons and Rings
– The known moons and rings of Uranus orbit in the planet’s equatorial
– New moons are frequently being discovered causing frequent changes in
the count.
– Uranus’s rings are very
dark—almost black.
• The existence of Neptune
was predicted, based on
small deviations in the
motion of Uranus, before it
was discovered.
• In 1846, Neptune was
discovered where astronomers
had predicted it.
• The Voyager 2
probe flew past
Neptune in
Neptune’s Atmosphere
– Neptune is slightly smaller
and denser than Uranus,
but it is still about 4 times
as large as Earth.
– Other similarities between
Neptune and Uranus
their bluish color,
magnetic fields, interiors,
and particle belts.
– Neptune does have
distinctive clouds and
atmospheric belts and
zones similar to those of
Jupiter and Saturn.
Neptune’s Moons and Rings
– Neptune has many moons, the largest being Triton.
– Triton has a retrograde orbit, which means that it orbits backward, unlike
virtually every other large satellite in the solar system.
– Triton also has a thin atmosphere and nitrogen geysers.
– Neptune has 6 rings that are composed of
microscopic-sized dust particles.
• Pluto was discovered in 1930.
• Pluto is very different from the other eight planets of our solar system
and does not fit into either the terrestrial group or gas giant group.
• The density of Pluto indicates that it is made of half ice and half rock,
and it is smaller than Earth’s moon.
• The atmosphere is composed of methane and nitrogen, but in unknown
• The orbit of Pluto is so eccentric that at aphelion, it is 50 AU from the
Sun, and at perihelion, it is almost 30 AU from the Sun.
• Pluto’s rotational axis is tipped so far over that its north pole actually
points south of its orbital plane.
• Many of Pluto’s properties are more similar
to those of the gas giants’ large moons
than they are to those of any other planet.