Astronomy Assignment #1: The Celestial Sphere and The Apparent Motion of
the Stars and Sun (Summer 2015)
Your Name______________________________________
This assignment is due on Thursday, 11 June
Submit this cover sheet with your assignment.
Complete the assigned problems from the text listed below and address the Instructor Assigned Topic. Mathematical
problems may be hand written. Write out the problem, show your work in solving the problem and state your answer in a
complete sentence. Failure to complete all three of these tasks will result in less than full credit awarded. The Instructor
assigned topic must be typed.
Text Problems: Answer the following Review Questions from Nick Strobel’s AstronomyNotes: Chapter 3: Astronomy
Without a Telescope
1. What motion of the Earth produces the apparent motion of the stars around us?
2. How many degrees is 30 arcminutes? How many degrees is 10 arcseconds?
3. How do the positions of the celestial equator, celestial poles, zenith, and meridian depend on the latitude of the
observer? (note: This is really a four part question. Answer each part separately.)
4. During a night, how do the stars move? What angle does their nightly path make with respect to the eastern and
western horizons? How does it depend on latitude?
5. What reference point is a celestial object on when it is at its highest position above the horizon?
6. Why do observers in the northern hemisphere see celestial objects north of the celestial equator for more than 12
hours?
7. For northern hemisphere observers, which celestial object would be above the horizon for the greatest amount of
time: one that is at 0° declination (on the celestial equator), one that is 30° declination (above the celestial
equator), one that is 70° declination (farther above the celestial equator), or one that is -40° declination (below the
celestial equator)? Which one would be above the horizon the greatest amount of time for southern hemisphere
observers? Explain your answer.
8. How does the Sun move with respect to the stars during the day? ...during the year?
9. Why does everyone have 12 hours of daylight on the equinoxes?
10. Why is the length of daylight in the northern hemisphere so short on December 21?
11. When will the Sun be at its highest altitude in the year in Los Angeles or Seattle? How about Singapore (on the
Equator)? Why?
12. On what date is the Sun above the horizon the shortest amount of time for the Southern Hemisphere? Why?
13. At what two azimuths does the celestial equator intercept the horizon?
14. Why do astronomers prefer using right ascension and declination as opposed to using altitude ad azimuth?
15. What is the azimuth of any object when it crosses the meridian at any time of year in the southern sky?
16. What is the Sun's altitude on June 22 when it crosses the meridian in Syracuse, NY (+43 N).
17. What is the altitude of the NCP at Fairbanks, Alaska (lat. = 65° N)?
18. What is the maximum altitude of the Sun on the spring equinox for people on the equator? What is the Sun's
azimuth and right ascension at that time?
19. What will the Sun's declination be on the following dates: June 21, March 21, September 22, and December 21?
20. If the Sun sets 10° away from due West on October 20, what is the sunset azimuth?
21. If the Sun rises 12° away from due East on April 19, what is the sunrise azimuth?
22. What causes precession?
23. Which star is the current pole star? Which star was the pole star 2,000 years ago? Which star will be the pole star
8,000 years from now?
24. Why is there a difference between the sidereal day and solar day?
Instructor Assigned Topic:
Sketch the apparent motion of the stars, following the example in class, looking in the four cardinal directions (N, E, S &
W) for the following four locations: The North Pole (90 N), Syracuse, NY (43 N), The Equator (0 N), Punta Arenas,
Chile (53 S). Include all relevant timescales (time for stars to complete once cycle and time that stars are above the
horizon) and all relevant angles (altitude of Polaris, declination of the circumpolar boundary, slant angle of rising and
setting stars looking east and west, declination of the southern (or northern) most visible star).
You should sketch and label a set of four figures similar to those shown below for each location.
Location___________________________
North
Altitude of Polaris = _____
Declination of the boundary
of the Circumpolar region =
_________
Time stars are above the
horizon = _______
East
Slant angle of rising stars =
_________
Time stars are above the
horizon = _______
South
Declination of the
southernmost visible star =
_________
Time stars are above the
horizon = _______
West
Slant angle of setting stars =
_________
Time stars are above the
horizon = _______