1. Chapter 29 The Solar System
The Planets

2. Overview of Our Solar System
M V E M J S U N P (Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune, Pluto) (My Very Energetic Mother Just Sent Us Nine Pizzas.)
All planets and their moons (satellites) orbit the Sun in the same direction.
All orbits lie in the same plane except Pluto’s orbit.

4. Early Ideas
Planets slowly change position each night relative to the position of the stars.
Geocentric Model – Use to think Earth was the center and sun, stars, & planets orbited us.
Planets orbit to the east as viewed from earth, but occasionally move in the opposite direction (RETROGRADE MOTION).

5. Early Ideas
Copernicus suggested that sun is center of solar system (Heliocentric Model)
Earth and inner planets, which are closer to sun move faster in orbits and pass up outer planets at certain points in their path making them appear to move backwards.

6. Early Ideas
Kepler’s First Law = Planets orbit the Sun in an ellipse, not a circle.
1 Astronomical Unit (AU) – average distance between the sun and earth. (1.496 x 108 km) Other planets’ distance from sun is compared to that of the earth.

7. Early Ideas
Perihelion – point in elliptical orbit when planet is closest to sun.
Aphelion – point in elliptical orbit when planet is farthest from sun.

8. Early Ideas
Galileo first person to use a telescope to observe sky. (Saw 4 largest moons of Jupiter)
Newton – studied gravity (attractive force between two bodies that depends on their masses and the distance between the two masses. Also found that each planet orbits a point between it and the sun called the center of mass, which is closest to the heaviest body.

9. Section 29.2 The Terrestrial Planets
Inner four planets
Close to size of earth
Solid, rocky surfaces
Mercury, Venus, Earth, Mars

10. The Solar System

11. Mercury
No moons
1/3 size of earth.
Slow rotation (Its revolution (year) is 1/1/2 of its days!)

12. Mercury

13. Mercury
No atmosphere
Hot daytime 427 degrees Celsius; Cold night –173 degrees Celsius. Largest temperature difference of all the planets.
Cratered surface with smooth lava created with lava flows similar to our moon.
High density suggests a Nickel-Iron core with molten interior.

14. Venus No moons Brightest planet in our nighttime sky
Covered with thick clouds of sulfuric acid
Very hot
Rotates slowly
One day is 243 Earth days

15. Venus
Clockwise spin (opposite the spin of other planets) (Rises in west & sets in east) Retrograde rotation
Sister planet to Earth (most like earth in diameter, mass, density)
Atmosphere of carbon dioxide which causes Greenhouse effect!
Few impact craters; smooth surface indicates volcanic activity
Internal structure probably similar to earth.

16. Venus

17. Earth Third rock from the sun
Distance from sun allows water to exist as solid, liquid, & gas.
Liquid water required for life
Atmosphere is 78% nitrogen & 21 % oxygen supports life
Mild greenhouse effect
Tilted 23 ½ degrees on axis causes seasons
Wobbles as it spins (precession) due to gravitational pull of moon and sun.

18. Earth

19. Mars
Red planet (iron in soil)
Smaller & less dense than earth
2 moons (Phobos & Deimos) probably captured asteroids
Atmosphere similar to Venus, with lower pressure and density & no greenhouse effect.

20. Mars Windy; dust storms
Southern surface is cratered; smooth northern surface with 4 giant shield volcanoes
Dried river & lake beds suggest water once existed on Mars; has some carbon dioxide ice (dry ice) at poles.
Probably a solid nickel & iron core.

21. Mars = The Red Planet

22. Section 29.3 The Gas Giant Planets
Outer planets are gas giants composed of fluids, gases and small solid cores.
H, He, C, N, O (all light weight)
15 to 300 x mass of earth
4 – 10 times the earth’s diameter

23. Section 29.3 The Gas Giant Planets

24. Jupiter largest planet
11 x larger diameter than earth & 10 x smaller than sun
70% of all planetary matter in solar system
banded appearance (flow patterns in atmosphere)
4 major moons + at least 12 smaller ones

25. Jupiter
volcanic moon Io (Europa, Ganymede, Callisto) made of ice & rock
H & He atmosphere
10 hour rotation (shortest of any planet)
Great Red Spot giant storm on surface
Has a ring

26. Jupiter’s Red Spot is a Storm

27. Saturn 2nd largest rotates rapidly for its size
H & He atmosphere and ammonia clouds
Extensive ring system made of rock & ice ( 7 major rings made of smaller ringlets) May have come from an asteroid that collided with planet.
18 moons (Titan is larger than earth’s moon)

28. Saturn

29. Uranus Blue planet 18+ moons & 10 rings (dark in color)
methane atmosphere reflects blue light (H & He)
Rotates almost on its side
May have been knocked sideways by an asteroid.
Cold

30. Uranus
Tilted on its side.

31. Neptune Slightly smaller than Uranus
Blueish color due to methane atmosphere
Great Dark Spot (storm ) similar to Jupiter’s Red Spot disappeared in 1994
8 moons (Triton is largest; retrograde motion ; orbits backwards; has nitrogen geysers)
6 rings made of dust particles

32. Neptune
The dark spot is a storm similar to the one on Jupiter but not a large.

33. Pluto
solid surface, but not classified as terrestrial due to low density & small size.
Made of half ice & half rock
Smaller than earth’s moon
Methane & nitrogen atmosphere

34. Pluto
Pluto’s one moon Charon is shown in the upper left corner.