1. The sun makes up about 99% of our solar systems mass.
AIM: What is Astronomy? Do Now: Answer the following question in your notebook. Where is the sun in our solar system? What percent of our Solar System’s mass is occupied by the Sun? (if you added everything together)
The sun makes up about 99% of our solar systems mass.

2. Why do some objects appear to be moving in space?
Astronomy is the science that studies the universe and all objects in it.
**Apparent motion= what an object appears to be doing, not what it is actually doing**
Why do some objects appear to be moving in space?

3. Which one is true? I. Two Views: Geocentric: Heliocentric:
- Earth is motionless at the center of the universe with all planets revolving around it. (could not explain motion of the sun)
Heliocentric:
- Sun is the center of the solar system; all planets revolve around it. (simple explanation)
Which one is true?

4. II. Planetary Motion
1. The path of each planet (orbit) around the sun is an ellipse, with the sun as one focus.
- a focus is an object that a planet moves (orbits) around.
Johannes Kepler

5. Eccentricity = Distance between the foci
- Eccentricity measures the ellipse and describes it’s shape.
Eccentricity = Distance between the foci
Length of the major axis
ESRT Cover
Focus 1
Focus 2
Major Axis

6. Eccentricity = 1 (a line) Eccentricity = 0.5 Eccentricity = 0
- Eccentricity can described a planets ellipse as:
Eccentricity = 1
(a line)
Eccentricity = 0.5
Eccentricity = 0
(a circle) F
Most Eccentric F F
Least Eccentric
From the back table take an Ellipse worksheet from the top bin and a ruler

7. 2. The closer a planet is to the Sun (foci) the faster it revolves.
Slower

8. III. Measurement in Space
Astronomical unit (AU)
- it is about 150 million kilometers.
- is the average distance between Earth and the sun.
Light Year
- the distance light travels in one year.

9. In which diagram does the star have the greatest gravitation force?
IV. Gravitational Force
increases as distance between objects decrease. (closer together = stronger force)
increases as mass increases. (more mass = more force)
In which diagram does the star have the greatest gravitation force?
The greatest mass and least distance

10. V. Other Motions:
Retrograde Motion
- the apparent reverse motion of a planet as compared to the background stars.

11. Obtain your review book from the back of the room.
Closure:
Obtain your review book from the back of the room.
Review Book
p #1-4
1) 2) 3) 4)
p #1-13
1) 2) 3) 4) 5)
6) 7) 8) 9) 10)
11) 12) 13)

12. Eccentricity = Distance between the foci
Closure:
- Obtain an “Intro to Astronomy” worksheet (back bottom bin)
Using your ESRT and the notes answer the questions.
Eccentricity = Distance between the foci
Length of the major axis
Focus 1
Focus 2
Major Axis