1. The Celestial Sphere
Model describing the sky. (Glass bowl over the Earth)
Pretend that the stars are attached to it
Celestial Meridian: Line North to South.
Zenith: Spot straight up.

2. Celestial Sphere The sun and stars rise from East to West.
What causes this?
Earth’s Rotation
What star is that?
North Star (Polaris)

3. Finding Your Latitude Find the Big Dipper. Use Pointing stars.
Measure angle from ground to the North Star.
That angle is your latitude.

4. North Star from different latitudes
At the North Pole, where is the North Star in the sky?
Answer: Straight up!
At the Equator, where is the North Star in the sky?
Answer: On the Horizon!

5. Right Ascension (RA)
Corresponds to longitude, but different units are used.
Instead of 360°, a circle is broken into 24 hours of right ascension.
So, 360° = 24 h R.A., 15° = 1 h R.A., and 1° = 4 min R.A. Right ascension increases from west to east (note that we are looking at the exterior of the celestial sphere in the above picture).

6. Declination (Dec)
Corresponds to latitude - relative to the celestial equator (0° dec).
Circles of constant declination are all parallel to the celestial equator

7. With the two numbers of declination and right ascension, the position of any object in the sky can be precisely described.

8. Ecliptic Stars are fixed relative to each other.
The Sun traces out a circle on the celestial sphere called the ecliptic.
Ecliptic is tilted at an angle of 23.5° with respect to the celestial equator.

9. The Ecliptic & Zodiac

10. First Point of Aries

11. Cardinal Directions
Why is East & West
switched?

12. Equatorial Starmaps

13. Reading a Map Key – Different objects Magnitude Identify Zodiac
Plotting RA & Dec. of stars
Plot a moving or wandering object over time.