1. Chapter 28 Notes
Our Solar System

2. Our Solar System

3. The Inner Planets (and Pluto)

4. All the Planets (and Pluto)

5. The Planets and the Sun (and Pluto)

6. Formation of the Solar System
Nebular Theory:
Interstellar cloud contracts and spins
Dense center begins nuclear fusion (sun)
Remaining material forms planetesimals and then planets

7. Historical Solar System Models
Geocentric (Earth-centered) model
One problem was how to explain retrograde motion
Copernicus’ heliocentric model
1543, Polish scientist
Planets (including Earth) orbit the Sun in circular orbits
Supporting evidence collected by Tycho Brahe

8. Kepler’s laws of planetary motion
Johannes Kepler inherited Tycho’s data after his unexpected death.

9. Galileo First person to use a telescope to observe the sky
Discovered moons orbiting Jupiter
Also observed sun spots, phases of Venus, and Moon craters

10. Newton and Gravity
Newton’s discovery of the law of universal gravitation provided an explanation for the heliocentric model of the solar system

11. Zone 1: Inner Planets Terrestrial: “Earth-like” Small
Composed of rock (high density)
Close to the Sun
Few or no moons
No rings

12. Mercury Smallest Closest to the Sun No moons No atmosphere
Cratered like the Moon
1 orbit = 1.5 rotations (2 years = 3 days)

13. Venus No moons Earth’s “twin” in size Rotates backwards
1 day = 243 Earth days
Very high CO2 concentration in the atmosphere causes super greenhouse effect
Surface temperature of 464C!!
Can be seen as a bright morning or evening “star”

14. Earth One moon Tectonically active O2 in atmosphere
Water exists in all 3 phases
Mild greenhouse effect to keep the planet warm enough for life

15. Mars The red planet CO2 atmosphere 2 moons (Phobos and Deimos)
Has seasons like Earth, but a year is twice as long
Largest volcano in the solar system: Olympus Mons
Once had liquid water, has polar CO2 ice caps

16. Outer Planets Gas giants or “Jovian”: Jupiter-like Large Low density
Lots of moons
All have ring systems
Far from the Sun

17. Jupiter Largest planet Banded appearance Great red spot
Faint ring system
4 large moons, more than 60 total
Rapid rotation (10 hours = 1 day); shortest day of all the planets

18. Saturn Famous for ring system More than 55 moons
Density lower than water
Largest moon, Titan, has an atmosphere of nitrogen and methane
Another moon, Enceladus, shows evidence of geologic activity

19. Uranus Discovered in 1781 Rotational axis is 98 At least 27 moons
Rings are dark and nearly invisible
Appears blue because of the way it reflects light

20. Neptune Discovered 1846 13 moons Distinctive clouds and belts
Predicted before it was discovered
6 rings composed of dust particles
Largest moon, Triton, orbits backwards

21. Other Solar System Objects
Dwarf planets
Asteroids
Kuiper belt objects (KBOs)
Comets (the Oort cloud)