1. Bell Ringer
Take out your notebook
Draw a line under your last bell ringer answers
Put today’s date in the left hand margin
Complete Day 1 Bell Ringer Questions

2. Stars Essential Question:
How is the Hertzsprung Russell (H-R) Graph used to classify stars?
Stars
Essential Question:
How is our Sun similar or different than other stars?

3. What is a star?
A large spherical body that is composed of gases and emits light.

4. Characteristics of Stars
1 - Size of stars
*Stars are measured in solar radii
*The Sun is measured at 1 S.R. (solar radius)

5. Size of Stars Star Size (in solar radii) The Sun 1 Polaris 46 Rigel 78
Betelgeuse
1200 (approx)
VY Canis Majoris
1,400 (approx)
UY Scuti
1,700 (approx)

6. Size of Stars

7. Characteristics of Stars
2 – Color and Temperature
*The color of a star indicates its temperature
*Blue – White – Yellow – Orange – Red (Hottest) (Coolest)

9. Characteristics of Stars
3 - Magnitude (brightness of stars)

10. Characteristics of Stars
*Apparent Magnitude - How bright a star appears to be from Earth
Star
Apparent Magnitude
The Sun
26.8
Sirius
-1.46
Vega
+0.03
Betelgeuse
+0.5

11. Characteristics of Stars
*Absolute Magnitude
How bright a star actually is
Star
Apparent Mag
Absolute Mag
The Sun
26.8
+4.8
Sirius
-1.46
+1.2
Vega
+0.03
+0.6
Rigel
+0.12
-8.1
Betelgeuse
+0.5
-7.2

12. Bell Ringer
Take out your notebook
Draw a line under your last bell ringer answers
Put today’s date in the left hand margin
Complete Day 2 Bell Ringer Questions

13. Hertzsprung-Russell Diagram
A graph measuring the star's absolute magnitude (brightness) against its temperature (color).