1	Astro 1050 Fri. Sep. 19, 2003 Homework #2 Solutions Example test problems
2	Homework #2 1. If you were kidnapped and transported to a distant location on Earth, but noticed that Polaris was 20 degrees above the horizon, what could you figure out about your whereabouts? c. The latitude of my location is 20 degrees north.
3	Homework #2 2-5. Lunar phases/lunar positions: What is the phase of the moon if at sunset it is near the eastern horizon? Full What is the phase of the moon if at sunset it is on the meridian high in the south? First Quarter What is the phase of the moon if at sunset it is in the southeast? Waxing Gibbous What is the phase of the moon if at sunset it is in the southwest? New
4	Homework #2 6. In which one of the following constellations might it be possible to someday see the planet Jupiter? (Hint: You might want to look at the star charts in Appendix B or elsewhere in Chapter 2.) Leo, which is the only Zodiac constellation on the list of answers.
5	Homework #2 7. What must be the phase of the moon if a lunar eclipse is to take place? Full! 8. What must be the phase of the moon if a solar eclipse is to take place? New!
6	Homework #2 9. While all of the following are discoveries of Galileo, which of the four listed is NOT one which DIRECTLY contradicts the "Aristotelian" view of the heavens. a.The discovery of "imperfections" on celestial bodies, such as mountains and valleys on the moon and changing sunspots on the sun. b.The discovery of the phases of Venus, ranging from new to crescent to "quarter" to gibbous to full. c.The discovery that the Milky Way is actually composed of a large number of very faint stars. d.The discovery of four moons orbiting Jupiter.
7	Homework #2 10. What is the circular velocity of Mercury? You will need values from Appendix A of the textbook. You might also find the example in By the Numbers 4-1 on page 62 useful. About 50 km/s.
8	Homework #2 11. In Star Wars, Han Solo claims the Millenium Falcon can make the Kessel Run in less than 12 parsecs. Huh? That's a distance, not a time! Star Wars fans claim this line doesn't refer to a trip in the conventional way, but rather a specific smuggling task. You should now know where the term parsec comes from. What is the parallax of a star 12 parsecs from Earth? 1/12 of an arcsec.
9	Homework #2 12. One of the nearest and brightest stars in the (southern) sky is Alpha Centauri. Assume that its radius is the same as that of the sun. The distance to Alpha Centauri can be found in Appendix A of the text. Assuming a perfect telescope and no atmospheric turbulence, what is the angular diameter (not radius!) of the star as seen from Earth? 7 x 10^-3 arcseconds. Angular diameter = 206265 arcsec x 2Rsun 4.3 light years
10	Example Test Questions If you could see stars during the day, this is what the sky would look like at noon on a particular day. The Sun is near the stars of the constellation Gemini. Near which constellation would you expect the Sun to be located at sunset on the same day? GEMINI
11	Example Test Questions Polaris is a 2nd magnitude star, and Phi Pegasi is a star about 16 times fainter than Polaris. What is the approximate magnitude of Phi Pegasi? c -14 c 3 c 5 c 18 c 25
12	Example Test Questions If we find a comet with an orbital period P = 27 years, then the semi-major axis (a) of its orbit must be c 1 AU c 4 AU c 9 AU c 20 light years c 100 light years
13	Example Test Questions True/False: Galileo observed that Venus has phases like the moon. The moon rises at the same time every night.
14	Example Test Questions Essay/short answer question: How does the moon slow Earth's rotation and how does the Earth change the moon's orbit? Your answer had better involve tidal forces and tides!