1. Our Sky & Constellations
(Power Point 02)

2. Student Learning Objectives
Construct a model of the Solar System
Identify locations on the celestial sphere model
Define locations in our sky
List attributes of constellations

3. What is the celestial sphere?
The celestial sphere model represents our view of motions in the sky.
Stationary Earth at Center
All objects orbiting Earth

5. Positions in the Sky Zenith (above) Nadir (below) Meridian (N  Z S)
Altitude (height)
Azimuth (N  E)

6. Degrees & Arcseconds There are 360° in a full circle.
Arcminutes: 1° = 60′
Arcseconds: 1′ = 60″
Extended fist = 10° Ɵ
Ɵ = 31 arcminutes

7. Practice How many arcseconds? a. 1° b. 1/2° c. 2° d. 2′
2) Through how many degrees does the Earth rotate in 1 hour?

8. What is a constellation?
Constellations were originally identified as visible groupings of stars that appeared to have a pattern.
Different distances
Different ages
Different brightness
a, b, g, d, e, z, …

9. Summer Triangle Asterism
Image Credit: space.com

10. Constellations
Circumpolar constellations are always above an observer’s horizon.
Seen all year
Never set
There are 88 constellations recognized by the IAU.

11. Image Credit: daviddarling.info
What is the Zodiac?
Image Credit: daviddarling.info

12. Practice
What is the difference between a constellation and an asterism?
Why do constellations appear to rise in the East and set in the West?
Can you name a constellation that is circumpolar?