1. Our Solar System

2. Early ideas about our solar system… Many early Greek scientists believed that we lived in a geocentric universe. A geocentric or earth-centered model is described with the earth in the center and all other planets, moons, Sun, and stars revolving around it.

3. This was NOT the case. Polish astronomer, Nicholas Copernicus published a different view in 1543. He proposed that the earth, along with the other planets and moons, revolved around the Sun. This is called a heliocentric or sun-centered model. Galileo discovered evidence to support Copernicus’ ideas when he invented the telescope in the early 1600’s. (He found Venus went through different phases just like the Moon)

4. Formation of our Solar System Solar Nebular Theory – the sun and the solar system were formed from a cloud of gas and dust more than 4.6 billion years ago.

5. The steps of the Solar Nebular Theory: 1) A gravitational attraction among the particles caused them to drift toward the center of the cloud. 2) As the cloud contracted (pulled in), it began to rotate (spin). 3) As more gas and dust were pulled toward the center of the cloud, it began to rotate faster and flatten into a disk. 4) The core of the cloud became so dense that nuclear fusion began – and our Sun was born! 5) The remaining gas and dust combined together to form our planets and their moons.

6. The Solar Nebular Theory

7. The Planets in our Solar System

8. Our Planets The planets in order from closest to farthest from the Sun: MercuryVenusEarthMarsJupiterSaturnUranusNeptune Pluto (dwarf planet now)

9. The Sun and Planets

10. Motions of our planets Orbits of the planets are ellipses (not circles) Planets closer to the Sun travel faster than planets farther away Outer planets take much longer to orbit the Sun than inner planets

11. The Inner Planets The Inner planets are also called the Terrestrial planets Mercury, Venus, Earth, & Mars are all terrestrial planets Terrestrial planets are small and rocky Terrestrial planets have few or no moons and no rings

12. MERCURY

13. MERCURY Closest planet to the Sun Surface is heavily cratered and looks much like our moon Very thin atmosphere (sodium, helium, potassium, hydrogen) Has the greatest extremes in temperature (450˚C on the daytime side and -170˚C on the nighttime side) Mercury has no moons

14. VENUS

15. VENUS Sometimes called Earth’s twin or sister planet because its size and mass are very similar Venus is covered entirely by a very thick atmosphere made of carbon dioxide and droplets of sulfuric acid Its atmosphere has 90 times more pressure than Earth’s The carbon dioxide (greenhouse gas) in the atmosphere traps in solar energy and causes a surface temperature of 470˚C (that is 878˚F!!!!!!) Venus has no moons

16. EARTH

17. EARTH Only planet in our solar system to have surface temperatures which allow water to exist as a solid, liquid, or gas 93 million miles away from the Sun (or 1 Astronomical Unit) 1 moon

18. MARS

19. MARS Called the “red planet” because iron oxide in its rocks gives it a reddish color Satellite pictures have shown a barren, rocky windswept planet Long channels in the soil appear to have been carved by running water in Mars’ past Largest volcano in the solar system, Olympus Mons, is found on Mars 2 small moons, Phobos and Deimos

20. The Outer Planets The outer planets are also called the Jovian planets Jupiter, Saturn, Uranus, & Neptune are all Jovian planets Jovian planets are large and gaseous Jovian planets have many moons and a ring system

21. JUPITER

22. JUPITER Largest planet in the Solar System Large atmosphere composed of gaseous hydrogen, helium, and some ammonia, methane, and water vapor Ocean of liquid hydrogen and helium lies beneath this gaseous atmosphere A small core of ice and rock The Great Red Spot (a never-ending storm on Jupiter’s surface bigger than Earth!) 4 Rings 63 Moons – 4 of which are the Galilean Moons

23. The Galilean Moons Io (volcanically active) Europa (like a large billiard ball) Ganymede (largest satellite in the solar system) Callisto (most heavily cratered object in the solar system)

24. SATURN

25. SATURN Known as the Ringed planet (has millions of rings) Saturn’s rings are composed of pieces of ice and rock and can range in size from pebbles to boulders tens of meters across Least dense of all the planets (could float in H 2 0) Large atmosphere composed of hydrogen and helium with small amounts of ammonia, methane, and water vapor Ocean of liquid hydrogen and helium below the gaseous atmosphere A small core of ice and rock 62 Moons

26. URANUS

27. URANUS Axis of rotation is at 90˚ (tilted on its side) Large atmosphere composed of hydrogen, helium, and methane (methane gives the planet its green/blue color) Ocean of liquid water, methane, and ammonia surround a probable rocky core 11 Rings 27 Moons

28. NEPTUNE

29. NEPTUNE Composition very similar to Uranus (hydrogen, helium, and methane) The Great Dark Spot (dark colored storm similar to the Great Red Spot on Jupiter) 4 Rings 13 Moons

30. PLUTO (the dwarf planet)

31. PLUTO Pluto is now a dwarf planet (A dwarf planet is defined as a celestial body orbiting the Sun that is massive enough to be rounded by its own gravity but has not cleared its neighboring region of planetesimals and is not a satellite) It is unlike all of the other outer planets Has a solid, rocky surface Its interesting orbit makes Pluto sometimes closer to the sun than Neptune No rings 3 Moons (Charon – very close in size to Pluto, Hydra, and Nix)

32. Video Clips Why is Pluto not a planet? Why is Pluto not a planet? http://m.youtube.com/watch?v=Z_2gb GXzFbs http://m.youtube.com/watch?v=Z_2gb GXzFbs Uranus…..how do you say it again? Uranus…..how do you say it again? http://www.youtube.com/watch?v=h3 ppbbYXMxE http://www.youtube.com/watch?v=h3 ppbbYXMxE

33. Other Objects in the Solar System

34. Comets composed of dust and rock particles mixed in with frozen water, methane, and ammonia Come from the Oort Cloud and the Kuiper Belt The Oort cloud is a cloud that completely surrounds the solar system and contains a large collection of comets The Kuiper Belt is far out beyond Neptune’s orbit

35. Structure of a comet a comet is similar to a large dirty snowball a comet has three parts: coma, nucleus, and tail the nucleus, the solid middle, is surrounded by the coma which is formed from vaporized gases

36. Structure of a comet

37. The Sun’s solar wind vaporizes the comet to create the tail After many trips around the sun, all that is left of a comet is small particles spread out in its orbit

38. Halley’s Comet (will return in 2062)

39. Meteoroids, Meteors, and Meteorites Meteoroid – small pieces of rock moving through space (often broken off pieces of comets) Meteor – meteoroid that burns up in Earth’s atmosphere (this is what we call a shooting star) Meteorite – meteoroid that is too large to completely burn up in the Earth’s atmosphere and strikes Earth

40. Meteoroid Meteor Shower Meteorite http://www.youtube.com/watch?v=5Y3I1 w5Becs http://www.youtube.com/watch?v=5Y3I1 w5Becs

41. Asteroids

42. Asteroids pieces of rock similar to the material that later formed into planets most asteroids lie in the asteroid belt between Mars and Jupiter Ceres, once the largest asteroid known, is now a dwarf planet Here are some others: others: