Chapter 7 : Mentos

Chapter 7 The Jovian Planets

Observations of Jupiter and SaturnThe Discoveries of Uranus and NeptuneBulk Properties of the Jovian PlanetsJupiter’s AtmosphereThe Atmospheres of the Outer Jovian WorldsJovian InteriorsSummary of Chapter 7

Units of Chapter 7

Jupiter can be imaged well from Earth, even with a small telescope.Here: Jupiter with its Galilean moons

7.1 Observations of Jupiter and Saturn

True-color image of Jupiter

Natural-color image of Saturn

Cassini image of Jupiter, true color

Uranus, in natural color. Note the absence of features.

7.2 The Discoveries of Uranus and Neptune

Neptune in natural color

The Jovian planets are large and much less dense than the terrestrial planets; Saturn is less dense than water!

7.3 Bulk Properties of the Jovian Planets

Jovian planets, compared to Earth

Peculiarity of Uranus: Axis of rotation lies almost in the plane of its orbit. Seasonal variations are extreme.

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:

7.4 Jupiter’s Atmosphere

No solid surface; take 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.

The Galileo probe descended into Jupiter’s atmosphere and returned valuable data. The arrow indicates its entry point.

Major visible features:Bands of clouds; Great Red Spot

Two examples of smaller storms merging, first into a smaller red spot, second into existing Great Red Spot

The atmosphere of Saturn is similar to that of Jupiter, except that Saturn is somewhat colder and its atmosphere is thicker.

7.5 The 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; see only top layer.

Saturn also has large storms, and bands.

Storms near Saturn’s equator

Enormous thunderstorm on Saturn

Rotation of Uranus can be measured by watching storms.

Neptune has storm systems similar to those on Jupiter, but fewer. The large storm system at top has disappeared in recent years.

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.

7.6 Jovian Interiors

Magnetic fields of Uranus and Neptune must not be produced by dynamos, as the other planets’ fields are.Interior structure of Uranus and Neptune, compared to that of Jupiter and Saturn:

Jupiter’s magnetosphere:Intrinsic field strength is 20,000 times that of Earth.Magnetosphere can extend beyond the orbit of Saturn.

Aurorae are seen on Jupiter, and have the same cause as those on Earth – the interaction of solar wind particles with the magnetosphere.

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.

How do we know what the internal structures of the Jovian planets are like?A. Probes have been sent into the

interiors of the planets and have returned data about the conditions.

B. Astronomers use the Earth's internal structure as a basis of comparison.

C. Astronomers examine the composition of the satellites of these planets.

D. Astronomers use information about the physical characteristics as well as laws of physics to obtain theoretical models.

Which of the following statements is FALSE?A. Interior heating in the Jovian planets

contribute to convection in the atmospheres.

B. Slow rotation rates lead to very strong coriolis forces.

C. The circulation patterns tend to be in very elongated bands that encircle the planets.

D. The circulation speeds increase towards the equator.

Near the core of Jupiter, hydrogen isA. a low temperature gas.B. a high temperature gas.C. a solid.D. a liquid.E. a liquid metal.

The great red spot of Jupiter is thought to be

A. caused by an enormous volcano.B. a region of hotter gases.C. a long-lasting cyclonic storm.D. an opening through the high level

clouds revealing a portion of the atmosphere nearer the surface. 

Which of the following are true about Jupiter's belts (dark) and zones(light)

A. belts are rising while zones are sinking.

B. belts are sinking while zones are rising.

C. both belts and zones are rising.D. both belts and zones are sinking. 

Jupiter's magnetic field probably originates

A. in the liquid metallic hydrogen region.

B. from the solar wind.C. in the vicinity of Io.D. from the motion of the

Galilean satellites.

Compared to Earth, the expected seasonal changes on Uranus because of its orbital and spin-axis alignments will be

A. much less.B. very much exaggerated.C. absent, because of the alignment

of the spin axis.D. the same .

From the results of the voyager 2 mission of Uranus, we now know that the

A. planet has fewer rings than expected.

B. magnetic field has a large tilt to the spin axis.

C. larger moons have smooth surfaces and little evolution.

D. rings are made of objects hundreds of meters in radius. 

Since Uranus has a higher average density than Saturn

A. it must rotate faster.B. it must have much more rocky

material.C. it must have a stronger magnetic

field.D. it must have a higher concentration

of icy materials.

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.

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.