1. Locating Objects in the Night Sky
Where is it?
Locating Objects in the Night Sky

2. The Celestial Dome
The Celestial Dome is the sky as we see it with the naked eye.
Until about 500 years ago, we assumed that the entire universe was contained in an “inverted bowl” that stretched from horizon to horizon, 180◦ around.
We still use the term Celestial Dome as a convenient way to map the sky as we see it.

3. The Horizon
The Horizon is the edge of the Celestial Dome, where the Dome meets the Earth, 180⁰ around (again!)

4. Altitude and Azimuth
Altitude and Azimuth are simple ways to locate where an object is in the sky.

5. Altitude
Altitude (Alt.) is the angle of Elevation in degrees to the object from the Horizon.
The Horizon is at 0° Alt.
Directly UP is the… Zenith at 90° Alt.
Straight DOWN is the… Nadir at – 90°Alt .

6. Azimuth
Azimuth (Az) is the angle from North, measured clockwise in degrees.
North = ° Az. East = ° Az.
South = 180° Az. West = 270° Az.

7. Finding Azimuth
A Compass shows the direction of the Magnetic North Pole.
An Azimuth Ring is a circular scale which rotates and is used to find the Azimuth of an object.

8. The Problem of the Two Norths
True North is where the Earth’s true axis is.
Magnetic North is at not the same location as True North; in fact, Magnetic North changes over time.
Azimuth is measured from True North, so we must correct for it.

9. Magnetic North is 13° East of True North in California.
(This is called the angle of deflection.)
When finding Azimuth you need to take that into account. SO either…
Add 13° ~or~
Set the azimuth dial (if you have one) so that North is 13° west of the direction the needle points.