Final Exam Study Guide

1) Give four methods whereby we can calculate the distance to galaxies. Explain each method in detail.

2) Briefly describe two key pieces of evidence that support the Big Bang theory.

3) Why does the Big Bang theory predict that the Cosmic Background radiation should be blackbody?

4) Explain the missing mass problem.

5) What is the Hubble law?

6) What is Olber’s paradox? How does the Big Bang theory resolve Olber’s Paradox?

7) What is the critical density?

8) What evidence supports a “flat” universe?

9) What does it mean when astronomers say the early universe was “opaque”? What happened when the universe became transparent?

10) What information can an astronomer find from the spectrum of a star?

11) How does an astronomer find temperature from a stellar spectrum?

12) How does an astronomer find velocity from a stellar spectrum?

13) How does an astronomer infer a planet’s rotation rate from its spectrum

14) How does a spectrum of a binary system help an astronomer find the masses of the stars?

15) How do we measure the distances to the nearest stars?

16) How does the spectra of near stars, along with their distances and brightnesses, allow us to calculate the distance to far stars?

17) What determines how long a star will remain on the main sequence. Explain why.

18) Explain what a Hertzsprung Russell Diagram is and how astronomers use it.

19) TF A light year is a unit of time.

20) TF It will take me light-years to complete this test!

21) How do stars produce energy?

22) What evidence do we have that neutrinos oscillate?

23) What makes the North Star special?

24) Explain why we see the phases of the moon.

25) TF Last night I saw Jupiter right in the middle of the Big Dipper.

26) TF Last night I saw Mars move westward through the sky in its apparent retrograde motion.

27) Why does a planet undergo retrograde motion. Explain with a diagram. How long does this motion typically take? Can both inferior and superior planets undergo retrograde motion?

28) You are at latitude 44^o and longitude 92^o. Describe where you need to look for Polaris. Using your star maps answer the following questions. Can Betelgeuse ever be at your zenith? Explain why or why not. Which star could be close to the zenith today at midnight? Check your answer with Starry Nights.

29) On Earth, we see the Moon rise and set in our sky each day. If you lived on the Moon, would you see the earth rise and set each earth day? Why or why not?

30) What planets are currently visible in our night sky?

31) Why is Venus always close to the sun?

32) TF Last night I saw Venus shining brightly on the meridian at midnight.

33) TF The latitude of stars in Orion’s belt is about 5^o.

34) Explain the difference between altitude, latitude, and declination.

35) Does the sun ever appear at our zenith in Northfield? Explain why or why not.

36) What is conservation of angular momentum? Explain how angular momentum conservation affected the final shape of out solar system.

37) Why is Newton’s version of Kepler’s third law so important to our understanding of the universe?

38) TF Newton’s version of Kepler’s third law allows us to calculate the mass of Saturn from the orbital characteristics of its moon Titan.

39) Explain why we don’t have an eclipse every full moon.

40) From the blackbody curves below, explain which is the hottest object and explain how you know.

41) Explain when you expect to see absorption lines in a spectrum, when you expect to see emission lines in a spectrum, and when you expect to see a continuum.

42) Give the names of three types of electromagnetic radiation. Which has the highest energy? Which has the longest wavelength? Which has the highest speed?

43) TF Because of their smaller frequency, radio waves must travel through space slower than gamma rays.

44) TF If a distant galaxy has a substantial redshift (as viewed from our galaxy, then anyone living in that galaxy would see a substantial redshift in a spectrum of the Milky Way Galaxy.

45) TF If the Sun’s surface became much hotter (while the Sun’s size remained the same), the Sun would emit more ultraviolet light but less visible light than it currently emits.

46) A standard light bulb has a hot tungsten coil at a temperature of 3000 K. The temperature of the sun is 5800 K. Overall do you expect the light from a standard bulb to be the same as, redder than, or bluer than the light from the Sun? Why? Use your answer to explain why professional photographers use a different type of film for indoor photography than for outdoor photography.

47) Briefly describe the observed patterns of motion in our solar system. How does the current theory for the formation of the solar system explain these patterns.

48) Summarize the differences between the terrestrial planets and the Jovian planets.

49) Explain how temperature differences in the solar nebula led to the condensation of different materials at different distances from the protosun.

50) Know the planets and their order from the sun. Know which can be seen with the naked eye. Be able to give a description of the appearance of each.

51) Describe the equivalence principle and how it predicts time dilation and the bending of light in a gravitational field.

52) What is gravitational lensing? According the general relativity why does it occur?

53) What are gravitational waves? What evidence supports their existence?

54) What is degeneracy pressure? How does it differ from thermal pressure? Explain why degeneracy pressure can support a stellar core against gravity even when the core becomes very cold.

55) What is the common characteristic of main sequence stars?

56) What is a planetary nebula?

57) What is a neutron star? What supports a neutron star? What’s a pulsar? How do we know that pulsars must be neutron stars?

58) Suppose you are orbiting a black hole. You throw a clock with blue numerals toward the black hole. Explain what you see.

59) Why is a black hole “blacker” than a blackbody?

60) What is declination? What is right ascension?

61) What is the ecliptic? Which constellations mark the ecliptic? If a friend told you that she saw Mars in the constellation Casseiopia, would you believe her?

62) Explain why the moon goes through phases.

63) Explain the cause of the seasons.