1. Solar System
Expectations: D2.1, D2.4, D2.5, D3.3

2. The Solar System
Consists of the Sun, eight planets and their moons and billions of celestial objects.
Planets:
must orbit a star
have enough mass to be pulled into a stable sphere shape by gravity
dominate its orbit (Pluto does not dominate its orbit! Dwarf planet)

3. Retrograde Motion
The apparent motion of an object in the sky, from east to west, rather than its normal motion from west to east.
The Earth travels around the Sun faster than Mars. As Earth passes Mars in its orbit, Mars appears to first stop and then travel backwards in the sky before continuing forward again. (only with planets beyond Earth)

5. Astronomical Unit = the distance between the Earth and the Sun (1AU = 150 million km)

6. Inner Planets

7. Outer Planets

8. The Sun

9. Asteroids
Small celestial objects in the Solar System composed of rock and metal.
The asteroid belt lies between Mars and Jupiter.

10. Meteoroids
Piece of metal or rock in the Solar System smaller than an asteroid. (dust to size of a car or building)
If they get pulled into Earth’s atmosphere, they will burn up (friction), it is then called a meteor. Commonly called a shooting star.
If it reaches Earth it is called a meteorite.

11. Arizona impact crater

12. Meteorite

13. Comets Large chunks of ice, dust and rock that orbit the Sun.
The gas tail form points directly away from the Sun and a dust tail forms in the direction from which the comet came.

14. Comet

15. Homework
Page 317 # 5, 6, 9