GEOLOGY 422/522 by Kari Hetcher and Scott Hughes


Chapter 14 Interiors of the Giant Planets by William B. Hubbard
Chapter 15 Atmospheres of the Giant Planets by Andrew P. Ingersoll
Chapter 16 Planetary Rings by Joseph A. Burns
Chapter 17 Io, by Torrence B. Johnson
Chapter 18, Europa, by Ronald Greeley
Chapter 19, Ganymede and Callisto, by Robert T. Pappalardo


There is such a difference between the first four planets from the sun and the rest that they are classified by two different names. The inner planets, Mercury, Venus, Earth, and Mars, are the terrestrial planets, having solid surfaces and distinct internal structures. In contrast, the outer planets, Jupiter, Saturn, Uranus, Neptune, are called the Jovian planets (Pluto is in a class by itself, because it resembles one of Neptune's moons more than the other planets). The Jovian planets do not have solid surfaces and little is known about their internal structure. The following diagram shows the (probable) interiors the Jovian planets and Earth

The Jovian planets are composed of thick layers of gas and clouds, similar in chemical composition to the primordial solar nebula that once began our solar system.

Obviously, no human has visited the outer planets, since it would take approximately 6 years to even get to Jupiter (that’s how long it took the Galileo probe) and almost another 6 years to reach Saturn.

The Hubble Space Telescope and satelites have sent  pictures and information back to Earth. These explorations have helped us to learn much about the far reaches of the solar system.



Visit Jupiter -- The Fifth Planet From the Sun at Nine

This true-color simulated view of Jupiter is composed of 4 images taken by NASA's Cassini spacecraft on December 7, 2000.

Image Credit: NASA/JPL/University of Arizona

Study the linked concepts on the Nine Planets website for a complete overview of the historical aspects and physical properties of Jupiter.



Jupiter -- The Fifth Planet From the Sun

Jupiter, the fifth planet from the sun is the largest in our solar system, thereby justifying the name the Greeks gave it- Zeus,  the father of the gods.  We call the planet Jupiter, the Roman name for Zeus. Copernicus first realized the significance of this planet and its moons by observing the rotation of the moons around Jupiter.  Galileo supported Copernicus,and now the moons of Jupiter are referred to as the Galilean moons. Unlike the terrestrial planets, Jupiter is made up of thick layers of gas probably without a solid surface. Chemically, it is about 90% hydrogen, 10% helium, with traces of methane, water, and ammonia.

For a quick look at Jupiter from the Voyager and Galileo Missions, visit Jupiter at Welcome to the Planets. This PDS site by NASA JPL provides an excellent preview and overall descriptions of components in the Jovial system. Study the following important topics:

Visit the Students for the Exploration and Development of Space website at the University of Arizona for even more images and information. This website has tons of information about planets, stars, and the missions and technology we use to explore the universe.

How do we know so much about distant planets like Jupiter?

The Pioneer 10 and 11, Voyager I and II, and Ulysses missions gave us our first "close-up" view of Jupiter, and revealed many unknown facts about the planet's environment including detailed information on several of Jupiter's moons. Spaceprobe Galileo orbited Jupiter for eight years, and the Hubble Space Telescope continues to observe the Jovian system.

The Galileo satellite was equipped with a probe that descended through the cloud layers of Jupiter. The probe relayed information about the pressures, chemical compositions, cloud densities, and other data before it was eventually destroyed by the high temperatures and pressures.

For more information visit Spacecraft Galileo at Jupiter, a web site designed for children.

Click the picture to visit the Galileo Spacecraft website at JPL.


Other web sites to visit:

Galileo probe data-

Jupiter's Interior

Besides the Sun, Jupiter is the largest body in the Solar System, one of 17 bodies with a radius greater than 1000 km.

Visit the Planet Interiors website and scroll down to the comparison of all planetary interiors. What are the primary attributes of the interior of Jupiter? What other planet is closest in composition and planet properties to Jupiter?

More websites on the interior of Jupiter:

Interiors of the Jovian Planets - from the University of Oregon

Jovian Dreams: Cassini Compiles Best Map Of Jupiter - from Space Daily

Jovian Planet Systems: Interiors and Atmospheres from City Universitiy of New York

An Overview of Jupiter's Interior by University Corporation for Atmospheric Research (UCAR)


Jupiter's Atmosphere

From Earth, all we really can see of Jupiter is the outer layers of its dense atmosphere. Thick rotating clouds swirl around the planet, blowing in opposite directions in adjacent bands. The lighter colored bands are called zones, and the darker colored bands are called belts. This very unusual atmosphere produces huge storm systems with winds over 400 mph! An example of one of these storms is the famous Great Red Spot, which can be seen from Earth with a good telescope. The Great Red Spot is more than two times as large as the entire planet Earth and has existed for over 300 years. It can best be compared to a giant cyclone on Earth, though it is difficult to imagine such a dramatic and long lasting cyclone ever hitting the East Coast of North America! The internal heat produced by Jupiter may cause convective cells to form within the atmosphere and may be the driving force to these massive storms. Unlike most storms on Earth, the Great Red Spot moves with anticyclonic motion, or clockwise. The winds near the outside move at speeds of 100 meters per second (m/s), decreasing to only 5m/s at the center.

Fig_12p137.JPG (29608 bytes)Click for more information and pictures.

The diagram to the right (modified from our text) shows the chemistry of Jupiter's atmosphere.  As you can see, the chemistry changes depending on altitude, and it becomes increasingly more dense with depth. There is no "hard" surface on Jupiter and much of the planet is made up of molecular and metallic hydrogen, lying just beneath the swirling gaseous clouds of ammonia, methane, water and other chemicals we see from Earth.

The center of Jupiter is most likely a solid rocky core, but that remains speculative. There is evidence of liquid metal hydrogen surrounding the core, which could give Jupiter its magnetic field. Liquid metal hydrogen requires outrageously high pressures (over 4 million bars!), but Jupiter is so large that this may be possible

(Diagram to the right is based on calculations by J. Lunine, William Hubbard, "The Interiors of Giant Planets," in The New Solar System, edited by J. K. Beatty and Andrew Chaikin, Cambridge,MA: Sky Publishing, 3rd ed., 1990,131-139)

Visit the following websites:

An Overview of Jupiter's Atmosphere by University Corporation for Atmospheric Research (UCAR)



The Rings of Jupiter

During the Voyager 1 mission to the outer realms of the solar system, an amazing discovery took place. When the Voyager satellite was turned around for one last look near Jupiter, scientists saw a delicate ring around the planet. Closer examination of the ring, indicated that it was made up of very small grains of rock, probably cast off from nearby moons. For centuries, the rings of Saturn had awed viewers, but now we know that the phenomenon is not unique to Saturn. For more information on the Jupiter ring, see the following:

Click the thumbnail (above) of a ring (as seen from Galileo) to see a larger image.

Go to: Galileo Images of Jupiter or for more images and information.

The Main Ring of Jupiter is discussed on the NASA JPL website. The ring system of Jupiter was imaged by the Galileo spacecraft on November 9, 1996.

Jupiter's Rings Revealed =============>
Photo Credit: M. Belton (NOAO), J. Burns (Cornell) et al., Galileo Project, JPL, NASA

Jupiter's Rings -- A Continuing Story Of Discovery

Cornell News: Galileo finds Jupiter's rings formed by dust blasted off small moons


Rings are great, but......

HST22JULC.gif (25905 bytes)humans recently witnessed a Comet impact on Jupiter!

Comet Shoemaker-Levy 9

The summer of 1994 gave scientists a unique view into the inner atmosphere of Jupiter. Comet Shoemaker-Levy 9 was captured by Jupiter’s gravitational field and broken into several pieces. The Galileo satellite was fortunately near Jupiter at the time as was able to send back some amazing pictures of these cometary pieces as they zoomed through the clouds at 210,000km/hr and exploded deep within Jupiter’s atmosphere. The four black dots are explosions.

Check out these sites for more information and wonderful pictures of the impacts:


Jupiter's Moons -- all 28 of them (or is it 57, or 63?)!

Visit JPL's site called The Jovian System and click or scroll down to The Jovian Satellites. The four largest moons are also called the Galilean Satellites:

Use these sites and your textbook to help answer the Task Questions below that pertain to Jupiter's moons.

Also, a good overview of all of Jupiter's moons can be found at NASA's Solar System Exploration website.
Read the list of Jupiter's moons. Note that some of them have yet to be named.

Here is a fun Q & A to review:

QUESTION - I would like to know if the particles and rocks forming the rings are now slowly falling into Jupiter, and eventually the rings will be gone?

ANSWER - from Elias Barbinis (NASA) on April 14, 1997:
Jupiter's rings are formed by charged particles of various sizes. Most of these particles are very tiny (about 1 micron across -- what is a micron?).

There are two forces that are exerted on these particles by Jupiter. First a gravitational force and an electromagnetic force. The gravitational force is stronger than the electromagnetic force for particles with size of 1 micron and it provides the centripetal accelaration that is required to keep these particles in circular motion around Jupiter.

Throughout their lifetime these particles are ground down by the energetic particles that are abundant in Jupiter's magnetosphere and eventually they become so small (about 0.03 micron across) that the electromagnetic force overpowers the gravitational force and the particles leave the rings and fall into Jupiter's atmosphere. The lifetime of these particles is about 1000 years, which is very short in a cosmological sense. However, Jupiter's rings are a permanent feature because these tiny particles are regenerated continually by collisions of interplanetary micrometeoroids with boulder-size objects within the rings.

Module Task 1

Go to this Galileo-at-Jupiter website:

Review the information on Jupiter's Atmosphere found in the website and record the data as a spreadsheet. Either construct a table or otherwise figure out a way to illustrate the "altitude" (gets more negative with increasing pressure in the data table) of various atmospheric pressures and wind velocities. Using the diagram above, determine what types of chemical condensates (cloud layers) would be encountered in the pressure range shown by data table. Using this information and that from other websites as well as your reading, answer these questions:

Where do the different cloud types (condensates) occur in the atmosphere? Why?

What is the wind velocity profile in the upper atmosphere (troposphere)?

Can ices exist in the atmosphere of Jupiter? Where? What types?

What other questions would be good to ask about Jupiter's atmosphere and how would you go about finding the answer? (There is no right or wrong answer to this question.)

Module Task 2

1. How do the the Jovian and terrestrial planets differ in chemical composition? How did these differences come about? Why are the two classes of planets so different?

2. Comet Shoemaker Levy-9 broke into pieces and crashed into Jupiter. What caused the breakup of the comet? What would this kind of impact do to the planet Earth? Speculate (with numbers) on the largest meteorite hit (click and scroll down) that the Earth could take without causing world-wide environmental destruction.

3. Planets with an atmosphere (like Earth, Jupiter and Saturn) have weather. Write a hypothetical weather report for Jupiter. Include the area in or near the Great Red Spot plus at least one other area. Be sure to discuss convective cells, atmospheric winds, low and high pressure systems,and compare values to Earth weather.

4. How much larger would Jupiter have to be to become a star with nuclear fusion?

5. What are the primary differences between and similarities among the Galilean Satellites? Why?

6. Which Galilean Satellite would be a good candidate to explore for possible life? Why? Which one has active volcanoes? Why? Which one has higher impact crater density than just about any other planetary body? Which one is the largest?

Write up your module tasks and e-mail your report to the instructor.

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