1. Planet Motion Chapter 8, Section 1

2. Models of the Solar System The Ancient Greeks believed in the geocentric model. In the geocentric model, the Earth was at the center of the universe and that the stars consist of two spheres; one that was consistently spun around the Earth and one that seemed to wander (planet translates to “wandering star”)

3. Ancient Greek (Ptolemy) Geocentric model

4. The Ancient Romans did not seek out much in terms of science about the cosmos. They did however name three days of the week after it: –Saturday – Saturn –Sunday – Sun –Monday – Moon –(The other four were named after Norse gods; Tiu, Woden, Thor, & Friya)

5. In the geocentric model, the solar system would have been arranged in the following order:

6. A map of the Geocentric model

7. Copernicus In 1543, Copernicus came up with the heliocentric model Stated that the moon revolved around the Earth and all of the planets revolved around the sun. (Helios was the Greek god of the Sun.) Did not count on ellipses and thus his model could not accurately predict the location of the planets and was not widely accepted

8. Galileo Found that Venus has phases much like our moon Found that Jupiter has moons that revolve around it. This evidence further supported the heliocentric model. He invented the modern telescope and was the first person to document sunspots. Was forced by the church to recant all his findings 6/22/1623

9. Kepler Mathematician who took the work of other astronomers and put it together. Found that the paths of planets were ellipses Planets travel at different speeds.

10. Understanding the Solar System In the early 1600s, a German mathematician Johannes Kepler calculated the speeds of the planets and found that they were ellipses. He also learned that the speed of each of the planets was different and the outer planets took much longer to orbit the Sun (Mercury=88 days, Saturn= 29.5 years).

11. In the heliocentric model, the solar system would have been arranged in the following order:

12. Scientists now use two units to measure distance in space: –one is the astronomical unit which is equal to the average distance between the Earth and the Sun, and the light year which is the distance traveled by light in space in one year. (L.Y. = 9.5 Trillion km)

13. By definition, there are eight planets which consist of four terrestrial planets which are closer to the Sun and four gaseous giant planets which are further away. The terrestrial and gas planets are separated by a belt of rocky debris known as the asteroid belt. Beyond the orbit of the gas giants are no less than 100 small planet-like objects known as planetoids (including Pluto).

14. The solar system also contains a sizable collection of meteors, comets, and belts of rocky materials that also orbit the Sun. The solar system is thought to have formed from a condensing cloud of gas and dust known as a nebula. As the cloud contracted, it became super-heated and created our Sun. The remaining dust and gasses condensed into the planets.

15. Other Solar systems So far, over 300 stars have been found to have planetary systems. Upsilon Andromedae is one star with planets around it.

16. The Inner Planets Chapter 8, Section 2

17. Planets near the Sun The solar wind and heat have all but stripped most of the gases and lighter elements off of the terrestrial planets. (Planet size ratio is not accurate)

18. Mercury Smallest of the planets; size of our moon Has no atmosphere Surface temperatures vary from 427°C to -170°C

19. Mercury Taken by Mariner 10

20. Mercury in color

23. Mercury view from sun

24. Venus Size and mass similar to Earth Surface pressure is 92x greater than Earth Atmosphere is almost entirely CO 2 Surface temperatures vary from 450°C to 475°C RETROGRADE ROTATION: Backwards rotation of a planet

25. Venus As seen from Earth

26. Venus As pictured by Magellan spacecraft

28. It takes 223 days for Venus to revolve. Rotation takes 243 days! Notice something???? Thousands of volcanoes Silicon and Oxygen in crust

29. The Surface of Venus

32. Radar Images of Surface

34. Venus in front of the sun

35. Earth

36. Allows water to exist as a solid, liquid, and a gas Atmosphere burns up most meteors before they hit the ground Ozone in the atmosphere protects the life from U.V. rays Temp. range: -88 to 58 °C

38. Mars Known as the red planet due to the high level of iron oxide (rust) Has polar ice caps Appears to have once had flowing water on its surface Mars is tilted 25° on its axis and has seasons Atmosphere is mostly CO 2 and does not filter out harmful rays Surface temperatures vary from 37°C to -123°C Mars has two small moon; Deimos and Phobos ½ size of Earth!

39. Mars

41. NASA on Mars NASA sent probes to Mars in the 1970s and 80s but much more detailed information has come from the Mars Rovers; Spirit and Opportunity In 1996, structures identical in nature to some bacteria were found fossilized in a fragment of rock from Mars.

42. Mars Rover

45. A Face on Mars?

46. How Disappointing!

47. Evidence of Water?

51. Sunset on Mars

52. Olympus Mons: Largest Volcano in Solar System Three times taller than Mt. Everest 342 miles across

54. What do the inner planets have in common? small Planets with a solid surface are called terrestrial Contain iron cores Crust contains heavier elements

55. The Outer Planets Chapter 8, Section 3

56. The Outer Planets Why are the outer planets so different? The outer planets have large amounts of lighter elements such as H and He. Are not as affected by the solar wind than the inner planets

57. Jupiter Is the largest planet Composed of hydrogen and helium SIMILAR TO THE SUN! As you get closer to the surface, the pressure is equal to 50 million Earth atmospheres and the temperature is apx. 20,000°C Thin rings

58. Has continuous storms that cause swirls in the atmosphere Has more than 60 moons, of which Io, Europa, Ganymede, and Callisto are thought to have water and conditions possible for life to occur

59. Jupiter

61. Jupiter with moons

62. Comet that struck surface in ‘94

63. Eclipses on Jupiter

64. Aurora on Jupiter

65. Saturn Saturn is the second largest planet; HYDROGEN AND HELIUM! Has rings made of chunks of rocks and ice Has 53 moons The largest is Titan

66. Saturn

67. Saturn Edge View

68. Saturn Surface

69. Saturn Aurora

71. Uranus Axis is tilted on its side (north to south) Has a blue/green color due to its methane atmosphere Has 27 moons

72. Uranus

73. Uranus with rings

74. Infrared Image of Uranus

75. Neptune Was actually predicted by mathematical calculations before it was ever seen (It was known that an object was affecting Uranus’ orbit) Has blue color due to methane in its atmosphere Has 13 moons The largest is Triton –Has poles covered in ice –Has eruptions

76. Neptune

78. The Great Dark Spot

79. What do the outer planets have in common? Large and gaseous Have rings H and He make up atmospheres Many moons Iron cores

80. Planetoids (Pluto) Is smaller than the Earth’s moon Has its own moon, Charon Another planetoid is Sedna

82. Pluto and Charon

83. Comets and other objects Comet – dust, ice, frozen water, methane, and ammonia, ROCK!!! Asteroids – chunks of rocks (>10 meters) Meteoroids – chunks of rocks that can pass through the Earth’s orbit and into the atmosphere of the Earth; SOME OF THESE ARE LEFT BEHIND BY COMETS (<10 meters)

84. Comet

87. Hale~Bopp Comet

89. Asteroid

90. Another Asteroid

91. Asteroid belt between Mars and Jupiter

92. Meteor vs. Meteoroid. vs. Meteorite METEROID: a rock that travels aimlessly in space METEOR: a streak of light we see when a rock is burning up in the atmosphere METEORITE: if the rock makes it to the ground, it’s now a meteorite.

93. Meteoroid

94. Meteors: known as shooting stars!

95. Meteor Shower: Leonid

96. Meteorite!

97. When Meteors Attack

100. Chapter 8, Section 4 Is There Life Beyond Earth

101. Life on other worlds? All living things contain CARBON on Earth Most life forms on Earth need water and a comfortable temperature…….but…… Life has been found to exist in places with extreme living conditions on Earth These extreme living conditions include scalding hot areas, freezing cold areas, completely dark areas, etc.

102. Life on Europa, Jupiter’s Moon The surface is covered in large moving chunks of ice that are possibly made of frozen water.

103. Europa, Getting Closer…

104. Close up of Europa

105. Titan, Saturn’s Moon Nitrogen atmosphere….don’t plants on Earth use nitrogen? Contains hydrocarbons…isn’t life on Earth based on carbon? Surface pics show old riverbeds of ethane….and liquid METHANE!!! These are hydrocarbons.

106. Titan’s Surface from Sky… yes, it’s real

110. Titan’s surface