celestial sphere activity

Celestial Sphere (Spring Class)
Name ______________________________________
Objective: Students will use the celestial globes to understand the concept of the celestial
sphere and celestial coordinates. To give students practice in locating and positioning objects
using the equatorial coordinate system.
Important – you may find it helpful to use your notes on Celestial Coordinates (p. _______)
1. Today’s date is ______________
CAUTION: These spheres are delicate instruments that can be easily damaged or broken.
Please be careful and follow all directions when handling and carrying the globe. You are
responsible for any damage to the globes. They cost about $200 each.
Follow the instructor’s directions and set your celestial sphere for today’s date and for the
latitude of York, PA.
_____ is your celestial globe tilted to the north - Polaris is 40 o above the horizon
_____ is the sun set for today’s date?
_____ is the earth rotated so PA looks up to zenith?
_____ do you understand where our horizon is? (silver horizontal ring)
2. What imaginary line on the celestial globe is an extension of the earth’s equator and is
represented by the seam between the N. and S. hemispheres of the large plastic globe?
3. Find a couple of constellations that you are familiar with. Why are the constellations reversed
from those seen in the real sky?
4. What is the name of the imaginary line in the sky which is shown marked off with days and
months on the globe? What does this line represent?
5. How are the names of CONSTELLATIONS shown differently from the names of important
Stars? (note how the names are printed – case sensitive)
6. Without changing the settings, rotate the large sphere so that the Sun is setting on the
western horizon. Keep PA pointed to the zenith. About 2 hours after sunset, what very bright
star (C) is visible nearly overhead? What constellation is this star in?
7. A) In what compass direction (from York, PA) would you look to find the constellation
Cassiopeia at midnight? How high above the horizon would you look?
B) Rotate the clear globe to the west – note that the Sun is below the horizon (=night). Can you
see Cassiopeia all night? How do you know this? Explain fully.

Make sure you know what lines and numbers are DECLINATION and which ones are
RIGHT ASCENSION. In items 8-12, identify the object that is located at the given
equatorial coordinates. Dec.= Declination, NOT December :>). Note that some of the
declinations are positive and some are negative ( - ).
8. R.A. 6 h 40 m / Dec. -17 o Object ______________________
9. R.A. 14 h 15 m / Dec. 19 o Object ______________________
10. R.A. 5 h 50 m / Dec. 7 o Object ______________________
11. R.A. 3 h 40 m / Dec. 23 o Object ______________________
12. R.A. 16 h 25 m / Dec. -24 o Object ______________________
In items 13-18, state the equatorial coordinates of the following stars/objects: note how
RA and declination are stated above.
13. Procyon R.A. __________ Dec. ______________ (in Canis Minor)
14. Altair R.A. __________ Dec. ______________
15. Spica R.A. __________ Dec. ______________ (in Virgo)
16. Rigel R.A. __________ Dec. ______________ (in Orion)
17. The Sun R.A. __________ Dec. ______________ (on today’s date)
18. M31 R.A. __________ Dec. ______________
19. Why can’t we see the stars of the constellation Capricorn on this date?
20. There are a number of stars and constellation we will never see from York, PA. Rotate the
celestial globe and notice that there are stars and constellations that NEVER rise above the
horizon (can you find the constellation called the Crux also known as the Southern Cross?).
They all are located at declination minus _______ degrees and higher. What is the R.A and
Declination of the Southern Cross (Crux)?
21. The second brightest star in the sky is Canopus at R.A 6h, 30m / Dec. -53 o . Can you see it
from York? Why or why not?
22. See the instructions in #1. Set the celestial globe for Mexico City (latitude 20 o ). Could you
see the Southern Cross from here? Where would you look? (direction and height or angle above
the horizon).
23. Set the globe for the North Pole (today’s date) and describe the path the stars travel. Where
is the sun? What is it like at the North Pole this time of year?