Download Chapter 7 The Jovian Planets

Astronomy
A BEGINNER’S GUIDE
TO THE UNIVERSE
EIGHTH EDITION
CHAPTER 7
The Jovian Planets
Lecture Presentation
© 2017 Pearson Education, Inc.
Chapter 7 The Jovian Planets
© 2017 Pearson Education, Inc.
Units of Chapter 7
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Observations of Jupiter and Saturn
The Discoveries of Uranus and Neptune
Bulk Properties of the Jovian Planets
Jupiter’s Atmosphere
Atmospheres of the Outer Jovian Worlds
Jovian Interiors
Summary of Chapter 7
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7.1 Observations of Jupiter and Saturn
• Jupiter can be imaged well from Earth, even with a
small telescope.
• Here: Jupiter with its Galilean moons
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7.1 Observations of Jupiter and Saturn
• True-color image of Jupiter
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7.1 Observations of Jupiter and Saturn
• Natural-color image of Saturn
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7.1 Observations of Jupiter and Saturn
• Cassini image of Jupiter,
true color
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7.2 The Discoveries of Uranus and Neptune
• Uranus, in natural color
• Note the absence of features.
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7.2 The Discoveries of Uranus and Neptune
• Neptune in natural color
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7.3 Bulk Properties of the Jovian Planets
• The Jovian planets are large and much less dense
than the terrestrial planets; Saturn is less dense
than water!
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7.3 Bulk Properties of the Jovian Planets
• Jovian planets, compared to Earth
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7.3 Bulk Properties of the Jovian Planets
• Peculiarity of Uranus: Axis of rotation lies almost in
the plane of its orbit. Seasonal variations are
extreme.
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7.4 Jupiter’s Atmosphere
• Atmosphere has bright zones
and dark belts.
• Zones are cooler and are higher
than belts.
• Stable flow underlies zones and
bands, called zonal flow.
• Simplified model:
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7.4 Jupiter’s Atmosphere
• Jupiter has no solid
surface; take the top of
troposphere to be 0 km.
• Lowest cloud layer
cannot be seen by
optical telescopes.
• Measurements by
Galileo probe show high
wind speeds even at
great depth—probably
due to heating from
planet, not from Sun.
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7.4 Jupiter’s Atmosphere
• The Galileo probe descended into Jupiter’s
atmosphere and returned valuable data. The arrow
indicates its entry point.
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7.4 Jupiter’s Atmosphere
• Major visible features:
– Bands of clouds and the Great Red Spot
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7.4 Jupiter’s Atmosphere
• Hubble Space Telescope (HST) observations of the
Great Red Spot: Merging spots are seen in the top
sequence. Lower sequence shows the shrinking
Great Red Spot between 1995 and 2014.
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7.5 Atmospheres of the Outer Jovian Worlds
• The atmosphere of Saturn is similar to that of
Jupiter, except that Saturn is somewhat colder,
its atmosphere is thicker, and its bands are fainter.
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7.5 Atmospheres of the Outer Jovian Worlds
• Saturn’s atmosphere is
similar to Jupiter’s,
except pressure is
lower.
• It has three cloud layers.
• Cloud layers are thicker
than Jupiter’s; we see
only the top layer.
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7.5 Atmospheres of the Outer Jovian Worlds
• Saturn also has large storms. This 2011 storm
generated its own band, as seen in this sequence of
images from Cassini.
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7.5 Atmospheres of the Outer Jovian Worlds
• This storm was observed by the Cassini spacecraft
in 2011 in visible light.
• The right-hand image shows an infrared image
taken after the band had faded in visible light.
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7.5 The Atmospheres of the Outer Jovian
Worlds
• Saturn, like Earth and Venus,
has enormous polar vortices that
resemble huge storm systems.
The southern vortex is shown in
the top image, northern vortex
on the bottom.
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7.5 The Atmospheres of the Outer Jovian
Worlds
• Rotation of Uranus can
be measured by
watching storms.
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7.5 The Atmospheres of the Outer Jovian
Worlds
• Neptune has storm systems similar to those on
Jupiter, but fewer. The large storm system at the top
has disappeared in recent years.
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7.6 Jovian Interiors
• No direct information is available about Jupiter’s
interior, but its main components, hydrogen and
helium, are quite well understood. The central
portion is thought to be a rocky core.
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7.6 Jovian Interiors
• Interior structure of Uranus and Neptune, compared
to that of Jupiter and Saturn
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7.6 Jovian Interiors
• Jupiter’s
magnetosphere:
– Intrinsic field strength is
20,000 times that of
Earth.
– Magnetosphere can
extend beyond the orbit
of Saturn.
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7.6 Jovian Interiors
• Aurorae are seen on Jupiter and have the same
cause as those on Earth—the interaction of solar
wind particles with the magnetosphere.
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7.6 Jovian Interiors
• Uranus and Neptune both have substantial magnetic
fields, but at a large angle to their rotation axes.
– The rectangle within each planet shows a bar magnet
that would produce a similar field. Note that both
Uranus’s and Neptune’s are significantly off center.
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Summary of Chapter 7
• Jupiter and Saturn were known to the ancients;
Uranus was discovered by chance, and Neptune
was predicted from anomalies in the orbit of Uranus.
• Jovian planets are large but not dense; they are fluid
and display differential rotation.
• Cloud layers have light zones and dark bands; wind
pattern, called zonal flow, is stable.
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Summary of Chapter 7, cont.
• Storms appear with regularity; the Great Red Spot of
Jupiter has lasted for hundreds of years (that we
know of).
• Due to conductive interiors and rapid rotation,
Jovian planets have large magnetic fields.
• Jupiter, Saturn, and Neptune radiate more energy
than they receive from the Sun.
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