STUDY SHEET FOR FINAL.

Final exam is on Chapters 7 through 13+epilogue, and the relevant lecture notes. You also need to know Kepler's laws and Newton's laws, since it is difficult to understand the detection and characterization of the orbits of extra-solar planets without understanding the basic laws of gravity and planetary motion.

The test will be about 20 to 25 questions, all as multiple choice questions. You do not need a scantron. Test answers are to be written on the first page of the exam sheets. Please contact me with any questions. (rwalterb@nmsu.edu)

Use lecture notes on web pages as the main guide for follow up study from sections in the book. Depending on your background and familiarity with science in general and astronomy in particular, you may need to at least some time studying the book. The list below lists most of the major topics we have discussed. I may have missed one or two but the notes will make that clear.

Chapters 7-9

• most likely places outside Earth in solar system to find life?

• what is a tidal force? Where to they play a role? What relevance to life might they have?

• greenhouse effect

• other heat source(s) for planets

• properties of terrestrial planets in context of likelihood of life

• space exploration: robotic missions versus manned missions (advantages and risks and relative cost of each)

• telescopes and most important properties of them

• space exploration: fly-by's, orbiting space craft, landers, return missions

• Where are we looking?

• the case for life on Mars

• the case for life on Jupiter's moon Europa

• Why is Earth located "just right'?

Chapter 10,11:

• What is concept of "habitable zone"

• What object(s) does this refer to?

• What does it depend on?

• How long can a star shine? How did we determine that?

• Which type of stars are hot, which type are cool?

• What determines the average temperature on a planet? Consider:
     properties of star
     distance from star
     presence of absence of greenhouse effect

• Difference between hot and cool stars in terms of their light output (luminosity)

Chapter 11:

• Detection techniques for finding planets around other stars. Which methods did we discuss, and how do they work?

• What is the Doppler effect? How is it connected to finding planets? What do we measure?

• What is a "transit"? Which telescope/observatory is famous for using this method?

• How does the amount the star light is dimmed in a transit depend on the diameter of the planet? How does that help to measure the size of the planet from a transit?

• Are transits common? What else can we learn about the planet from a transit?

• Can we take pictures of extra-solar planets? Why is it hard?

• What type of planets can we find these days? What is easier, finding them close to stars or far away from stars? Why?

• Can we find earth-mass planets?

• What has been discovered about extra-solar planets thus far? Make a list as you study that topic.

• What is the most favorable orientation at which we can look at an extra-solar system and detect the planets? Does it depend on which technique we rely on in our search technique? For example, can the transit method detect planets at all orientations? What is easier to find, large or small planets? Planets close to the star or further away?

Chapter 12:

• What is SETI?

• What is the Drake equation? What quantities does it contain? Which can we know, which do we have to "guess"?

• What is the likely most logically used wavelength regime to send signals or search for extra-terrestrial intelligence?

• Does it make sense to send signals out or to "listen"?

• What are the best stars to listen to?

• Have we sent any signals in the past? How were they encoded?

• How would we decide a signal is not natural but artificial and likely due to an intelligence?

• Challenge in looking for signals:
     were to look?
     broad wavelength range over which signals could be present. Finding needle in haystack.
     how much telescope time and money to devote to this?

Chapter 13:

• What are the extra costs/risks involved with manned versus unmanned space flight?

• Distinguish distance scales involved in:
      space missions to low-Earth orbit (what is that?)
      space missions to Moon
      space mission to planets in solar system
      missions outside our solar system. How long would it take at currently attainable speeds for space craft?

• Why does it cost so much energy to launch something in space?

• What is escape velocity?

• What are the challenges for human space flight to other stars?

• Einstein's theory of relativity, and the limits in implies to travel speeds

• Time dilation, twin paradox

• What is a "paradox"?

• What is the Fermi paradox?

• What are the possible "solutions" to the Fermi paradox?

• What is the "rare Earth hypothesis"?

• What are some arguments in favor of this?

A few example questions: see also Homework 6 and 2nd midterm. These are only samples, they do not cover all the material.

1. True or false? Even though no object with mass, and no information, can travel faster than the speed of light, in principle an astronaut could reach a star that is 500 light years away within the current average human life span.

2. For a star that is more massive and hotter than the Sun, the habitable zone will likely be:

a. About the same distance from that star as we are from the Sun.

b. Closer to the star than we are from the Sun.

c. Suitable to sustain life on a planet for much longer time than the Sun will be able to.

d. Further away from the star than we are from the Sun.

2. When a spacecraft is launched from Earth to go to the space station, most of the mass at the time of launch is in the form of:

a. supplies for the space station

b. water for the astronauts on board

d. the 7 astronauts on board

d. fuel

3. In the Doppler method for detecting extra-solar planets, we measure:

a. The motion of the planet by measuring the changes in velocity of the planet over time.

b. The motion of the star by measuring the changes in velocity of the star over time.

c. The change in brightness of the star over time.

d. The light coming from the planet, by blocking out the star's light.

4. Which of the following extra-solar planets would be easiest to detect by directly imaging the planet as it orbits the star?

a. A planet like Jupiter orbiting a star in the same orbit Pluto orbits our Sun.

b. A planet like Earth but orbiting further from the star than we orbit the Sun.

c. A planet like Earth in an orbit more like Mercury's orbit around the Sun.

d. A planet like Jupiter orbiting very close to its star.

5. Suppose that you are on a nearby star and look at the Solar System. You happen to see the Sun's brightness dimming as Jupiter transits across its disk. Given that Jupiter's diameter is about 10 times smaller than the Sun's diameter, how much fainter will the Sun become during this transit, compared to its normal brightness?

a. A factor 0.1 (so 10%). c. Only about one in a million.

b. A factor 0.01 (so 1%). d. There would be no effect on the Sun's brightness.

6. The velocity required to escape from the Earth's gravitational pull is about:

a. 10 m/s b. 1 km/s c. 11 km/s d. 300,000 km/s

7. True or false: The Space-X rocket needs to reach the escape speed asked for in the previous question in order to be able to visit the space station to drop off astronauts and any leftover Thanksgiving turkey.

8. Which kind of star has the longest life time?

a. Stars like the Sun.

b. Stars with more mass than the Sun.

c. Stars with less mass than the Sun.

d. All stars have equal life times.