Use these pages as a study guide, a list of terms, concepts, and relationships that you will want to understand for the exams. This sheet is not a synopis of the class notes or textbook. A few sample questions, some with answers, some without, are included. These are indicated with a preceding "Q?" symbol.
I have tried to cover the topics likely to show up in an exam question, however, this review is not guaranteed to be comprehensive. Exam cover the text and notes !

There are many terms and expressions whose definition you need to understand. Use the chapter reviews in the text, where many terms are highlighted, and also those terms specifically described in your class notes.

Telescopes:

• Review the operating principles of both major types of telescope:
  • Reflectors use curved mirrors to collect & focus light and can be manufactured large. If the mirror is constructed incorrectly, it can suffer from spherical abberation.
  • Refractors use curves lenses to focus light, and are limited to sizes less than about 1 meter. Lenses, made of glass, suffer chromatic abberation -- the focal point of the lens is different for different wavelengths of light.
• Know the advantages and disadvantages to each basic telescope type.
• Telescope "size" is defined by the diameter of the objective: either a lens or a mirror.
• Know the meaning of light-gathering power and resolving power.
• All major research telescopes are of the reflecting type. Be aware of the different designs for these telescopes. How do astronomers get the light "out" of the telescope to study and make a record of it ?

• Know the basic methods astronomers employ to make astronomical observations.
• Images of the sky are constructed using a variety of technologies. Photographs are chemical recorders of information, CCD camers record light digitally in electronic form. Which is used more commonly today ?
• Astronomers use spectrographs to split the light of an object up into its component colors.
• Spectrograms provide information on a celestial object's temperature, composition, line-of-sight velocity, density, and luminosity. How ?

• Space-based telescopes are required to observe in many parts of the spectrum. Understand how the Earth's atmosphere interferes with astronomical observations from the Earth's surface.
• Understand the advantages and disadvantages of space-based telescopes vs those on the ground.
• Radio telescopes use large dish antennae to record radio waves from astronomical sources.
• X-rays and gamma-rays are much harder to collect and focus than optical light. Astronomers have constructed special devices to capture this type of radiation.

• Know the ordering of the planets from the Sun.
• Know which planets are the terrestrial planets, which are the jovian planets, and which fit neither category.
• Be aware of and understand the primary differences between terrestial and jovian planets. Use Table 6.2 in your textbook.
• Know the approximate relative sizes and masses of the planets. Look at the appropriate columns in Table 6.1.
• Understand the term "density", and be able to compare the average densities of the planets (see "DENSITY" in TABLE 6.1)
• Know the approximate rotational period of the planets -- know which are "slow", which are "medium", and which are "fast" rotators.
• Understand the physical differences between comets, asteroids, and meteroids.
• Know which planets have been visited by spacecraft and on which objects have spacecraft actually landed. Develop a sense of how each planetary exploration mission changed our perspective and understanding of the properties of each planet.

For each planet be aware of their basic characteristics and how those characteristics compare with those of the other planets (at the level discussed to this point in the semester).

• Atmospheres: Which of the terrestrial worlds have one, which don't ?
  • Mercury: no atmosphere
  • Venus: dense, hot, atmosphere, 96% CO₂.
  • Earth: nitrogen/oxygen atmosphere, weather, precipitable H₂O
  • Moon: no atmosphere
  • Mars: dry, thin, cold atmosphere, 95% CO₂.
• Surface appearance and relevant processes:   Q? Which planets are heavily cratered ?   Which have volcanoes ?   Which have liquid water ?
• Which have moons ?   Which do not ?

• Understand and define the "zones" into which planetary scientists have divided up the Earth: inner core, outer core, mantle, crust, hydrosphere, atmosphere, magnetosphere. Be able to label each zone on a cutaway diagram of the Earth. What are the principal properties of each zone ?
• Know the different regions of the Earth's atmosphere: their names, primary features, and their ordering with altitude above the Earth.
  Q? In what region of the Earth's atmosphere is the ozone layer located?
• Define P-waves and S-waves. When doe they occur? How are they measured ? What does the study of these waves tell us ?
• Understand the term "plate tectonics". Know what process drives plate tectonics.
• Review the pattern of most geological activity (e.g., earthquakes, volcanoes) Do they form a pattern or are these events randomly distributed around the Earth ?
  • New crust is created at plate boundaries by upwelling mantle material.
  • Old crust is returned to the mantle in subduction zones. Subduction zones are usually located at deep ocean trenches.
  • Lighter continental crust "floats" on the more dense crust of the ocean basins.
• Review the definition of "half-life" for a radioactive element (Chap 7, More-precisely 7-2).
  Q? Why do scientists measure radioactivity of various minerals ?
• Understand the general form of the Earth's magnetosphere, and what effect the magnetosphere has on atomic particles blowing past Earth in the solar wind.
• Be sure to understand how aurora (the "Northern Lights", if seen at the north pole) are produced, and how it is related to the Earth's magnetosphere.
• Understand the source of the tides and their effect on the the Earth's rotation.

• Know the relative size, mass, and density of the Earth and Moon.
• Know the average distance to the Moon in light seconds and kilometers.
• Review the Moon's rotation rate - once about its axis for each orbit about the Earth. Understand why this must be true, if we see only one side of the Moon.
• Be able to describe the basic surface features discovered on the Moon: the highlands, maria, craters, impact basins, crater rays, rills.
  Q? How are these features distributed over the lunar surface ? Evenly or not ?
• Understand the differences (age, composition, surface features) between the highlands and maria on the Moon, which are the older regions, and how we know which are the older geological features.
• Understand the origin of lunar craters, and their relative distribution on the lunar surface.
  Q? Are there more craters on the maria or highlands ?
• Compare the near-side of the Moon to the far-side. What is observed on the far side ?
• Be aware of the conditions on the lunar surface, as experienced by the Apollo astronauts. What is the soil like ?
• Be able to describe the atmospheres on the Moon and Mercury.
• Review our current knowledge of the lunar interior-- the size of the crust, the nature of the Moon's core and mantle.
• Be aware of the scientific results of the Lunar Prospector mission (Discovery Box 8-2 in the text).

• Mercury is the closest planet to the Sun. What kind of orbital period does Mercury have ? What is Mercury's average distance from the Sun (especially with respect to Earth) ?
• Understand the appearance and motions of Mercury in our sky. Mercury is never found more than 28 degrees from the Sun. Why ? Mercury displays phases, like the Moon. Why ? When is Mercury normally visible to the Earth-bound observer ?
• Describe the overall surface characteristics of Mercury-- craters ?, volcanoes ?, oceans ?   Compare to the Moon, Earth and Venus.
• Know what is meant by "scarps" and "weird terrain", surface features photographed on Mercury, and how they may have formed.
• How does the density of Mercury compare to that of the Earth ? of the Moon ?   What clues does this density measurement provide about the interior of Mercury ?
• How and when has Mercury been explored by spacecraft ?

Telescopes & Detectors:

• Understand how light is collected and focused by telescopes. Sketch the light "path", based on textbook illustrations.
• Understand why astronomical images are "blurred" by the atmosphere, and review some of the techniques used by astronomers to compensate for this blurring.
• Q?   What is a digital image and how does it differ from a photographic image ?

• Review the technique of interferometry. How does it help improve astronomical observations ?
• Why are computers essential to modern astronomical research ?
• Understand the fundamental importance of observations over the entire elecromagnetic spectrum. In the past 40 years, astronomers have moved from optical, then radio observations to the ability to explore the whole spectrum. Q?   How does radio and x-ray astronomy complement optical observations ?
• Understand why radio telescopes are substantially larger than telescopes which work in the optical part of the spectrum.

• Be able to describe the solar system in general terms: contents, shape, size. What type of orbits do the planets mostly exhibit ? Any oddballs ?
• Be cognizant of how various planetary properties are actually determined by astronomers:
  • Mass - by applying Newton's laws of motion and gravity
  • Size - knowing the distance, and the angular size, and appplying the small angle formula
  • Distance - by radar ranging, applying Kepler's laws, and direct communication with spacecraft.
  • Density - by measuring mass and size.
  • Rotation rate - via direct visual observation, where possible, or by using radar when the surface is not easily visible.
  • Orbital period - by charting the planets motions around the sky
• Be able to outline the stages of planetary exploration, in a historical sense, and know about what missions are currently ongoing.

• Understand how geologists can map the interior of the Earth, without actually drilling holes all the way into the center.
• Be able to explain how the Earth developed its present atmosphere. Be sure that you understand all the steps in the evolution of the atmosphere, and how different our atmosphere would be today, if one of those steps did not happen.
  Q? What if plant life had NOT been able to get started on Earth ? how would this have affected the Earth's atmosphere?
• Q? Why is the ozone layer important?
  ANS: It absorbs the more energetic UV radiation from the Sun, preventing that radiation from getting through to the Earth's surface.
• Understand the concept of plate tectonics, and why earth scientists came to accept this theory as an explanation for the Earth's surface features.
  Q? What is the evidence for plate tectonics ?
  Q? How has the Earth's surface changed over the past 500 million years ?
  Q? What process is believed responsible for crustal plate motions ?
• Know how tides are produced. What does "differential gravitational force" mean ?
  Q? How are the tides affecting Earth's rotation ?

• Be able to explain how astronomers have inferred that lunar craters are impact craters, not volcanic in origin.
• Compare and contrast the maria and highlands on the Moon.
• Review explanations for why the lunar far side exhibits a strikingly different surface appearance than the near (Earth-facing) side.
• Understand the different theories for the origin of the Moon. Which one is currently favored ?   Why ?   What evidence exists to support this theory ?

• How have geologists attempted to explain the unusual surface features found on Mercury ? -- scarps, "weird" terrain, the Caloris basin ?
• Describe the evolution of Mercury from its formation to the present day.
• Why do we assume that Mercury has a metal-rich core of substantial size ?
• What are the science objectives of the MESSENGER spacecraft, enroute to Mercury ?