1. The Solar System
Chapter 23

2. 23.1- The Solar System
Earth-centered model- The idea that the sun, moon, and all of the stars revolved around Earth
Who believed? Early Greek Scientists

3. 2. Sun-centered model- The moon revolves around Earth, but all planets revolve around the Sun.
First proposed? Nicholas Copernicus in 1543

4. 3. Percent of mass Sun has of our Solar System- 99.86%
4. How solar system formed?
Large cloud of ice, gas, and dust began to contract, gravity pulled matter inward, formed sun, planets formed from remaining materials
- How long ago did it form? 4.6 billion years ago

5. 5. When did sun become a star
5. When did sun become a star? When the temperature of the core reached 10 million degrees Celsius.
6. Nuclear fusion- Atoms with low mass combine to form heavier elements.

6. 7. Inner planets:
1. Mercury 2. Venus
3. Earth 4. Mars
Another name? Rocky or Terrestrial

7. 8. Outer Planets:
1. Jupiter 2. Saturn
3. Uranus 4. Neptune
Another name? Gas or Jovian Planets

8. 9. Shape of planets’ orbit: elliptical
Who discovered this? Johannes Kepler in 1600’s

9. 23.5 Other Objects in Space
Comet- a large “dirty snowball” that circles the sun
How long does it take Halley’s comet to orbit the sun? about 76 years
2. What are comets comprised of?
Frozen gases, ice, and dust particles

10. 3. Oort Cloud- a large collection of comets surrounding the solar system
Located? Beyond Pluto’s orbit

11. 4. Meteoroid- piece of rock moving through space
Meteor- meteroid that burns up in Earth’s atmosphere
Meteorite- meteor that strikes Earth’s surface

12. 5. What are meteors commonly called? Shooting stars
6. Asteroid- piece of rock smaller than a planet

13. - Between what two planets is the asteroid belt? Mars and Jupiter
How do scientists suspect it formed?
- Strong gravitational tugs from Jupiter kept a planet from forming
7.Kupier Belt hundreds of icy objects beyond the orbit of Neptune