1. Chapter 3
The Solar System

2. How was it formed The Nebular Theory
Started as nebula about 5 billion years ago
Composed of hydrogen and helium
Nearby supernova sent shock waves through galaxy
caused gases to be pulled inward
supplied new elements
Shrank to a spinning disk –10 billion kilometers across
Gravity heated center to protostar - the sun

3. How was it formed Other matter spun around the new sun
gathered into clumps- protoplanets
Near the sun the light weight gases boiled away
Mercury, Venus, Earth, Mars
In those far away the gases did not boil away
Jupiter, Saturn, Uranus, Neptune
the gas giants

4. How was it formed
Around the protoplanets smaller clumps formed moons or satellites.
Pluto is thought to be a moon of Neptune that broke away.
Asteroid belt- clumps of rocks between Mars and Jupiter
Jupiter’s gravity stopped a planet from forming
Oort Cloud- Near the edge clumps of matter- home of comets.

5. History People have used the stars for ages.
Used constellations to set planting times
Used constellations to guide travels
Some lights in the sky wandered through the constellations
Called them “planets” which is Greek for wanderers

6. Ptolemy Greek scientist Placed earth at center of universe
Other objects moved in orbits around the earth
Because circle was considered a perfect shape, thought they moved in circular paths

7. Copernicus Polish astronomer
Found Earth and planets revolved around sun
In the same direction
At different speeds
Thought the orbits were circular

8. Kepler German mathematician and astronomer
Used others observations (Tycho Brahe)
Calculated the orbits of planets were ovals or ellipses
Closer to the sun - shortest time of orbit
Farther from the sun - greater time

9. Planets
Move in an elliptical orbit

10. Planets Period of revolution
the time it takes to go once around the sun
one year
Mercury 88 days, Pluto 248 years

11. What keeps them there?
Law of inertia - objects motion won’t change unless acted upon by an outside force.
Won’t change speed or direction
Why do they curve?
Gravity pulls them toward the sun

12. What keeps them there?
Inertia
Gravity

13. Rotation Planets spin on their axes One rotation is a day
Mercury 58 days, Jupiter 10 hours

14. Special Features of the Planets
Mercury
Many Craters
no atmosphere
no erosion
Slow rotation makes it hot and cold

15. Venus Thick atmosphere of carbon dioxide Sulfuric acid clouds
Greenhouse effect
carbon dioxide traps heat.
Makes Venus hotter than Mercury
Retrograde rotation - rotates backward

16. Mars Red planet- covered by iron oxide (rust) Mons Olympus -
Largest volcano in the solar system
Two ice caps
north - water -never melts
south -carbon dioxide melts in summer

18. Two moons of Mars
Phobos
Deimos

21. Jupiter

22. Jupiter Largest of the gas giants Huge storms - red spot
Small solid core
Liquid metal layer makes a huge magnetic field
Magnetosphere
Gives off more heat than it receives from the sun
Thin ring

23. Jupiter Gives off more heat than it receives from the sun.
By far the largest planet.

24. 16 moons
4 seen by Galileo helped change science

25. Saturn Similar to Jupiter Clouds, magnetosphere, gives off heat
Rotates in 10 hours - makes it bulge in the middle and flat at the poles
Low density- would float in water

26. Saturn
Many rings
complex system
made of water
weave in and out

27. Saturn
Many moons -
Titan- the largest is like the early Earth.

28. Uranus Twice as far from the sun as Saturn.
Covered with ocean of superheated water
Tilted on axis
Rings of methane ice
Many moons

29. Neptune Like Uranus Hydrogen and helium atmosphere
Surface of water and methane
Rings made of dust
Eight moons

30. Triton Large moon Thought to be captured Retrograde revolution
out of plane of Neptune’s rotation

31. Pluto Moon sized Made of methane Pink atmosphere on the sunny side
Moon Charon 1/2 the size of Pluto
Scientists think it is a moon broken away from Neptune
Orbit crosses Neptune
Orbit not in plane with other planets

32. Other Stuff Meteor- the shooting star -the light you see the sky
Meteoroid- solid rocky objects circling the sun
Meteorite- When a meteor hits the ground
Most don’t because they burn up in the atmosphere
Some meteoroids are iron and nickel
Some are stony
Others are combinations

33. Meteorites Leave a crater where they hit the ground
Meteorite Crater in Arizona
Evidence of meteorites from the moon and from Mars

34. Comets Chunks of dust and gas from the Oort Cloud that orbit the sun
When it gets close to the sun it gets hotter
Some of the gas and dust form a cloud around the head called the coma
Solar wind pushes the gases away from the sun and make the tail
Tail is pushed by the solar wind
Tail always points way from the sun

35. Solar wind
Coma
Tail
Nucleus

37. Comets Comets orbit the sun
Long period comets take a long time to go around
Thousands of years
Short period comets return every few years
Halley’s every 75 to 79 years
Last time in 1986
Suspect a nearby star disrupts the Oort cloud to send more comets toward sun.

38. Asteroids Chunks of planetlike material floating in space
Most between Mars and Jupiter
Most 1km in diameter
Ceres- 1000km in diameter
Some pass near Earth
Caused craters on moon, and inner planets

39. Looking for life On other planets
Need liquid water and moderate temperatures.
Earth is just the right distance to have the right temperatures
Looking for evidence of former life on Mars- used to have water.
On Titan atmosphere like early earth.

40. Rockets Rely on Netwon’s Third law of Motion
For every action there is an equal and opposite reaction.
Reward blast of hot gases causes rocket to shoot forward.
First developed by Chinese in 1000
Tube full of gunpowder with cap on one end.

41. Escape Velocity
The minimum speed needed to leave the gravitational pull.
Depends on mass of planet and distance from the center of planet.
Earth 11.2 km/sec
Moon 2.3 km/sec
Jupiter 63.4 km/sec
Pluto 0.3 km/sec
Sun 616 km/sec

42. Rockets and Escape Velocity
Solid rockets burn up fuel quickly
Large thrust early
Gravity eventually slows them down.
Liquid fuels provide continuous thrust.
Goddard- gasoline and liquid oxygen
Space shuttle liquid hydrogen and liquid oxygen
Multiple stages to reduce weight.

43. Spacecraft Probes have gone past all the planets except Pluto
Have sampled comets tails
Have taken pictures of planets and moons.