1	Astro 1050 Homework #2 Solutions given here on these pages.
2	Homework #2 1. 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.
3	Homework #2 2. The sun is on the celestial equator at the times of c. the autumnal equinox and the vernal equinox. These points define the transition of the sun between the northern and southern skies, when its path crosses the equator.
4	Homework #2 3. Suppose you lived on a planet that had a perfectly circular orbit, but whose axis of rotation was tipped 23.5 degrees away from the perpendicular to its orbital plane (the same as the Earth's). What kind of seasons would this planet have? b. The planet would have seasons very similar to the Earth's.
5	Homework #2 4. 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
6	Homework #2 5. If you were an astronomer in the Alpha Centauri system (assume 4.2 light years from Earth) looking toward the solar system, what would be the maximum angular separation between Jupiter and the sun you could ever see? (Hint: 1 ly equals 63,000 AU; you can look up the orbital radius of Juipter in Appendix A). a. Angular diam. = 206265 arcsec x 5.2AU 4.3 l-y x 63,000 AU/l-y Ang. Diameter = 4 arcsec
7	Homework #2 6. Relatively large "spring" tides occur a. at new moon and full moons – the textbook provides this answer in words as well as in a figure. When sun and moon lined up, the tidal stretching is in the same direction and largest.
8	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!
9	Homework #2 9-12. 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
10	Homework #2 13. If the moon rose at about 7pm one night (and you know now that its phase would be full or close to full, right?), at about what time will the moon rise the next night? [Note I am looking for the typical difference -- the fact that the orbit of the moon is elliptical can cause variation in the exact number.] This one is more involved than what we discussed in class so far, but if you follow it, you’re getting the concepts down well. The moon orbits the Earth every 28 days. From moonrise one day, to the same time the next day, the moon has gone 1/28 of the way around the Earth and the Earth must go 1/28 a turn farther for it to rise again. Because the Earth must turn farther, the rise is later. 1/28 of a 24 hour day is about 45 minutes, so 7:45 is the best choice.