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Chapter 3

Chapter 3. The Solar System. 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

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Chapter 3

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  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. Inertia Gravity What keeps them there?

  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

  17. Two moons of Mars Phobos Deimos

  18. Jupiter

  19. 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

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

  21. 16 moons • 4 seen by Galileo helped change science

  22. 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

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

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

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

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

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

  28. 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

  29. 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

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

  31. 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

  32. Solar wind Coma Tail Nucleus

  33. 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.

  34. 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

  35. 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.

  36. 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.

  37. 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

  38. 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.

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

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