Use these pages as a study guide, i.e., a list of terms, concepts, and relationships that you will want to understand for exams. A few sample questions, some with answers, some without, are included. These are indicated with a preceding "Q?" symbol. This material is not guaranteed to be comprehensive -- tests cover the text and class notes !

There are many terms and expressions whose definition you will need to understand. Make use of the chapter reviews in your textbook, where many terms are highlighted, and also those terms specifically described in your class notes.

MARS

• Mars is a superior planet-- the next furthest from the Sun after Earth. Q? How does this affect Mars' appearance on the sky ?
• Mars appears red to Earth-bound observerd, why ?
• Review Mars' orbital properties: average distance from the Sun, # of Earth-days needed to complete one Martian year(687).
• Be aware of the global properties of Mars, especially in comparison to Earth, e.g.: size, mass, mean density, surface temperatures, composition and pressure of the atmosphere, surface structures, rotational rates, and the seasons on each of the two planets.
• Know the main surface features on Mars, such as Olympus Mons (largest volcano in the solar system), Valles Marineris (an enormous canyon extending 4000 km across Mars' surface), polar caps, the Tharsis bulge, the difference between Mars southern highlands and northern plains.
• Understand the small-scale topographic features discovered on Mars by the Mariner, Viking, and Mars Global Surveyor spacecraft, and what these features tell us about the geologic properties of the surface, the presence of water, weather conditions, and the history of the Martian surface. Among those features are: impact craters with fluid (liquid) ejecta, runoff and outflow channels (evidence for liquid surface water in Mars' past), and sand dunes.
• Mars has two small moons: Phobos and Deimos. Describe their properties. Q? How are they similar to Earth's moon ? How are they different ?
• Mars possesses a thin (1/150th Earth's) atmosphere consisting of 95% carbon dioxide. Q? What's the weather like on Mars ? Mars thin atmosphere results in much stronger temperature day/night temperature variations. Dust storms can sometimes blot out large areas of the surface.
• Q? Has evidence for life been found on Mars ? Might there be life under the surface ? Why ?
• Review the debate over possibled fossilized Martian organisms found in meteorites. Q? What are "Martian" meteorites ? How did they arrive on Earth ?
• Review recent findings regarding the presence of subsurface water / ice deposits on Mars, returned by the spacecraft now in orbit around Mars. What are the implications of these findings ?
• Be cognizant of the history of martian exploration- from then 1960s, to today. Q? How many spacecraft have actually landed on Mars (and returned some data) ? What are the next steps in Mars exploration ?

• What are you looking at when you view Jupiter ? Describe Jupiter's appearance through a telescope.
• Be aware of Jupiter's motions and appearance in the night sky. Which constellations does Jupiter appear to move through ? How bright is Jupiter compared to other solar system objects ?
• Review the bulk properties of Jupiter.
  Q? How massive is this planet compared to Earth? compared to the Sun ? How does its density compare ? The composition of Jupiter (and the other outer planets) is very different from Earth's composition-- what is it?
• Jupiter has no solid surface. Know what its internal structure is believed to be like. Q? What exists at Jupiter's core ?
• Jupiter radiates twice as much energy as received from the Sun. Q? What is the source for this excess energy ?
• What are swirls, loops, and eddies observed in the Jovian atmosphere ? What is the Great Red Spot ? What are the zones and bands in the atmosphere? Review their relative temperatures and heights within the atmosphere.
• Jupiter possesses a powerful magnetosphere, driven by its fast rotation and inferred metallic hydrogen layer in the core. The planet is surrounded by a sea of electrically charged particles which are hazardous to people and electronics alike.
• Be aware that in July, 1994, the comet Shoemaker-Levy crashed into Jupiter's, the only such known event in history.
• Which spacecraft have visited Jupiter and when ? How did they change our view of the planet ?

• What are you looking at when you view Saturn ? Describe this planet's appearance through a telescope.
• Understand how Saturn compares to Jupiter. Which is bigger ? Which is more dense ?
• Understand Saturn's motions across the night sky, and its orbital properties. Q? How many Earth years comprise a Saturnian "year" ?
• Be aware of Saturn's bulk properties: size, mass, density, temperature. How fast does Saturn rotate ?
• What are the spots seen occasionally in Saturn's atmosphere ? What are typical wind speeds in the upper layers of the atmosphere ? What is the composition of the clouds in Saturn's atmosphere ?
• Which spacecraft have visited Saturn and when ? How did they change our view of the planet ?

• Understand the basic properties of the exceptional Jovian moon system, including the four large moons discovered by Galilieo.
  Q? What is their order in distance from Jupiter ? How does their sizes compare to Earth's moon ? Which is the largest moon in the solar system ?
• Review the geology and evolution of the Galillean moons of Jupiter.
  Q? What is exceptional about each ? Which moon has very active volcanoes ? Which is ice-covered and may hide a subsurface ocean ?
• Saturn has one large moon-- Titan. What are its unusual characteristics ? What is on the surface of Titan ? How do we know ? What might the Huygens probe, now enroute to Titan as part of the Cassini mission, find when it parachutes into Titan's atmosphere in 2004 ?
• Be aware of the significance of Saturn's medium-sized moons, the so-called "icy satellites". Describe some of their properties. Water ice is an important constituent of these moon's entire composition.

• Which planets have rings ? Are they all similar in size and composition ?
• What are Saturn's famous rings ? Review the overall dimensions of the ring system - width, thickness. Q? Are the rings solid, liquid or gaseous ? What is the overall composition ?
• Be aware of the factors that cause structure within the rings-- for example, the Cassini division is produced by the gravitational influence of the satellite Mimas.
• Understand the meaning of the term "Roche limit", and how this physical prinicple, related to tidal forces, might be responsible for producing the ring systems seen at Saturn and Jupiter.

• Understand why the gas giants could retain their light element (hydrogen and helium) atmospheres, while the terrestrial planets could not. Temperature and mass define the escape velocity of gases. Cold, massive planets can hold onto the light elements; warm, less massive planets cannot.
• Compare the Jovian and Saturnian atmospheres. How and why do they differ ? What is our current model for the layering and composition of the clouds ?

• Understand the dynamo theory as applied to the origin of planetary magnetic fields:
  To generate a magnetic field, a planet needs (in general):
  
  • a liquid, metallic core
  • fast rotation
• Understand why the dynamo theory seems to work in the case of Mars, which has no global magnetic field, as well as Jupiter, which has a strong field.

Understand how the numbers and sizes of impact craters on surface of a planet or moon can tell volumes about the age and properties of that surface. Old surfaces which are not eroded will show the cumulative effects of eons of meteoritic bombardment; whereas young surfaces will show few craters. Understand how we can date planetary/lunar surfaces:

• few visible craters --> implies a "fresh", geologically young surface.
• large numbers of craters --> implies an old surface, which has not been modified since the epoch when collisions were frequent in the solar system.

• Understand the evidence for flowing water in the past on the martian surface, and what circumstances would have allowed liquid water to have existed, even though it cannot exist as liquid today.
• Understand the effect Mars' seasons have on the appearance of the planet, especially the polar caps.
• Be able to describe why the Martian atmosphere is so different from the atmospheres of either Earth or Venus.
• Understand why Mars does not have a greenhouse effect, even though the majority of its atmosphere is CO₂.

• Understand why Jupiter and Saturn show a "flattened" appearance.
• Review our understanding of the interior properties of the gas giants. Why do we believe there is a metallic hydrogen layer deep in the interior of Jupiter and Saturn ?
• Jupiter and Saturn both emit more energy than they receive from the Sun. How does this energy source differ between Jupiter and Saturn ?

• Understand why Io is so volcanically active (frictional heat from tidal forces). Might this process also work on Europa ?
• Understand the evidence for a possible liquid subsurface ocean on Jupiter's moon Europa.
• Understand how the relative positions of each Galilean moon of Jupiter (meaning their distance from Jupiter), has defined their evolution and their current surface and interior features.
• Understand how distance from the Sun affects the temperature of objects (colder as one moves outward) and why that allows for entire moons composed of an ice/rock mixture in the outer solar system, but not in the inner solar system.

• Review how orbital resonances and sheparding moons may help explain some of the features (gaps, braided rings) in the ring systems surrounding some of the gas-giant planets.
• Understand the concept of a "Roche limit". The difference in gravitational force across an object when it gets too close to another more massive object can literally rip an object apart.
• What is believed to be the origin of the Saturnian ring system ? Are they a long-lived phenomenom or do astronomers believe that rings come and go ?