Review Questions for Exam 3 -- Astronomy 1210 -- Section 2

These questions are intended to make you think about the relevant topics for the exam. They are not necessarily the exam questions themselves.

The exam will consist of about 25 multiple choice questions and 5 or 6 short answer questions. The questions will primarily address topics covered in the lectures and the lecture notes and slides should be your guide to preparing for the test. The readings in the texts should help clarify the lecture notes. The test will contain a few general questions from the readings from the web.

All relevant equations will be provided at the top of the exam.

This test covers material in lectures 20 through 30 as outlined on the lecture notes web page - through the material on Venus. The material from the recent lecture on icy worlds in the outer solar system will be covered on Exam 4, not here.

Textbook readings: Chapters 7, 8, 9, 10, and 13 - plus sections 11.2 and 12.4. Mars is not covered on this exam, so the material in sections 9.4 and 10.4 is not covered on this test but will be on the Exam4/Final. Note that in general the book is much more detailed that the level of the material reviewed in class. The book provides good background but focus on the class discussion as highlighted by the html lecture notes and class powerpoints.

Web readings:

What fraction of the Solar System's mass resides in the Sun? Of the remaining mass, what fraction is in the Giant Planets? Where are the asteroids located? What characteristics distinguish Terrestrial planets from Jovian Planets (you should be able to name all of the planets in each category)? What material comprises most of the mass of the moons of the Jovian planets? What gas composes most of the mass of Jupiter (and the Sun as well)?

How do the regular features of our solar system suggest that the planets accreted from a flattened disk of dust and gas? How does a flattened disk of dust and gas form from a huge diffuse interstellar cloud (gravity and rotation should be a big part of your answer)? How does the process known as accretion work?

When a planetary system forms, why is it that if dust grains constitute only 1% of the material in the disk (the rest being gas) that the dust grains play the all-important role in building the planets? How are the Gas Giant planets built? Why do worlds dominated by rock and metal form in the inner solar system while moons in the outer solar system are dominated by ice? Why is this picture inconsistent with the ongoing discoveries of planets around other stars? What evidence is there that solar systems are forming around other newly-forming stars.

How do we currently detect planets in orbit around other stars? Roughly how many planets are known? What sort of planets are we regularly discovering? Why is the Doppler technique most sensitive to big planets close to their stars? Why can't we simply look directly at other nearby stars and directly observe their planets? What sorts of motions does Jupiter induce in the Sun as Jupiter follows its orbit around the Sun? How do "transits" reveal the presence of planets around some stars? What special orientation must exist for a transit to occur? What evidence do we expect to use to infer that some of the planets found might have life?

What actually happens when an atom undergoes a radioactive decay? What is a half life? How can you use radioactivity to estimate the age of a rock? What age are you really measuring by doing so? Where do you find the oldest rocks in the Solar System? How long ago did the Solar System form? Why does the asteroid belt exist? Why didn't a planet form there?

Of the 8 major planets, which one has a moon most similar in size to the planet itself? Why are the terms "near-side" and "far-side" most appropriate when discussing the Earth's Moon? What are the two major types of terrains on the near-side of the Moon? What are their characteristics? How do they differ in age? Why is it logical that planetary surfaces are most heavily cratered during the early history of the Solar System? Why are there few impact craters found on the Earth?

How do we use craters to determine the relative ages of different surfaces on the Moon? Does the Moon's far side look like the Moon's near-side? Why are there no "maria" on the lunar far side? Why are craters round regardless of the angle at which the impacting object strikes the surface? Why do some craters have central mountain peaks? What do "breccia" and "regolith" refer to? Why is the Moon volcanically dead today while the Earth still has active volcanoes?

How can the density of a planet be used to determine its composition? What materials are most commonly available to make planets and what are their densities? What is meant by "differentiation" and what does this processes have to do with the structure of the interior of the Earth?

What is striking about the density of the Moon (and thus its internal composition) compared with the Earth? How did the Moon most likely form? What lines of evidence point to this conclusion? Is it easy to make a Moon by this process? What significant influences does the Moon have on the Earth that may affect the likelihood that complex life could develop?

What features are evident when you look at the Earth's surface without the water? What does "plate tectonics" refer to? What makes the crustal plates move? How does plate tectonics produce mountains and oceans? What causes earthquakes? What is special about the amount of water on Earth? Should you expect to find many large craters in the ocean basins? Why?

What factors determine whether a planet can retain an atmosphere? Why does Titan (a big Moon of Saturn) have an atmosphere, but Mercury (a similar-sized planet with stronger gravity) does not? Where do atmospheres come from? (Outgassing vs. impacts)

What are the primary present-day constituents of the Earth's atmosphere? Did the Earth produce a lot of CO2? Why do we think so? What was the second most abundant gas in the original CO2-dominated atmosphere of the Earth? Where did the CO2 go? Where did the water for the oceans come from? Did the Earth's atmosphere always contain oxygen? If not, when did it appear? What produced the oxygen?

Why is the Earth's atmosphere poor protection against large asteroids? How have asteroid impacts influenced the course of evolution on Earth? How often do impacts occur which destroy a substantial fraction of life/species on Earth? How large does such an impactor have to be? What is the primary cause of death? What is the smallest diameter object that would significantly influence civilization? (100-300 meters) What does "significantly influence" mean? (widespread, but not global destruction, catastrophic tidal waves, slight climate influence, economic collapse). How many objects of this size are out there and on orbits where they will eventually find their way to Earth? What is the significance of the K-T boundary and the Chicxulub impact structure? What was the most recent impact event leading to the release of megatons of energy at the Earth's surface? How can civilization protect itself against such events in the future?

What is the primary constituent of the atmosphere of Venus? What is the atmospheric pressure there compared to Earth? What are the Venusian clouds composed of? How rapidly does Venus rotate? In what "direction"? If Venus is completely cloudy, how do we observe the surface? How does radar mapping work and what can it measure? What is the primary difference between the distribution of land on the Venusian surface compared with Earth? What do we know about the cratering of the Venusian surface and what does that tell us about the history of the surface? How geologically active is/was Venus? What is the Greenhouse effect and how does it work? What gas(es) is/are important? How much does the surface temperature of Venus increase as a result?