Name: Partner(s): Day/Time:

Identify the following things on the celestial sphere: equator, ecliptic, north celestial pole, horizon, and meridian on the celestial sphere.

1. Which of those is/are engraved on the plastic sphere?
   
2. Which is/are represented by the metal frame?
   
3. Which ones do you need to measure RA and dec?
   
4. Which ones do you need to measure the alt-az?

Adjust the sphere to show the stars at your latitude by changing the altitude of the north pole to your latitude (~42°).

5. Explain how to measure each of the possible coordinates on the celestial sphere:
   
   • RA:
     
   • dec:
     
     
     
     
     
     
   • alt:
     
     
     
     
     
     
   • az:
     
     
     
     
     
     

Identify the two stars you looked at in the planetarium on the celestial sphere.

6. Rotate the sphere until the first star is the farthest east of the meridian that it gets (spin the sphere around to find that position.) Record its altitude, azimuth, right ascension and declination in table 3.
7. Rotate the sphere until the first star is on the meridian and make the measurements again.
8. Rotate the sphere until the second star is just rising. Record its altitude, azimuth, right ascension and declination in table 3.
9. Rotate the sphere until the second star is on the meridian and make the measurements again.

Move the sphere back to the position when the second star was just rising. Find another star that is just rising but is in a different constellation.

10. What star is it? (if it is not named, write the name of the constellation it is in and draw a sketch showing its location). Record its RA and dec.
    
    
    
    
    
    
11. The third star is just rising, just like the second star, so at least one coordinate should be the same for both stars. Which coordinate(s) are the same?
    
    
    
    
    
    
12. Turn the celestial sphere until the second star is on the meridian. Is your third star on the meridian? If not, is it east or west of the meridian?
    
    
    
    
    
    
13. Turn the celestial sphere until the second star is setting. Determine the time is was above the horizon by counting the hours of RA along the same declination line that it is on.
    
    
    
    
    
    
14. Turn the celestial sphere so that your third star is setting. Determine the number of hours it was above the horizon.
    
    
    
    
    
    
15. Find your first star again and follow its path. How many hours a day is it above the horizon?
    
    
    
    
    
    
16. Stars that never rise and set are called circumpolar. From Ann Arbor (latitude 42.3°) all stars north of +47.7° dec are circumpolar. Where would you have to be for only stars north of +66.5° to be circumpolar?
    
    
    
    
    
    
17. Where would you have to be for all stars to be circumpolar?
    
    
    
    
    
    
18. Where would you have to be for no stars to be circumpolar?