The Planets (in two parts) The Inner Planets. The inner 4 planets are called Terrestrial planets

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1 The Planets (in two parts) The Inner Planets The inner 4 planets are called Terrestrial planets

2 What do you think? Is the temperature on Mercury, the closest planet to the Sun, higher than the temperature on Earth? What is the composition of the clouds surrounding Venus? Does Mars have surface liquid water today? Is life known to exist on Mars today?

3 First, we need some basics Within the solar system we measure distances with the unit of an Astronomical Unit This is the average distance between the Sun and the Earth

4 We will use the Earth as a basis for Comparison

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6 Mercury Large portions of Mercury weren t imaged until finally bought complete images of Mercury

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8 This image of Mercury is from NASA s Messenger probe from October 2008

9 Photographs from Mariner 10 (1973) reveal Mercury s lunar like surface. What are the similarities? What are the differences? What does that tell us about Mercury? Mercury Moon

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11 Caloris Basin Note the edge of a huge crater on the left, mostly in shadow.

12 Unusual, Hilly Terrain The tiny, fine-grained wrinkles are actually closely spaced hills.

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14 Mercury also has numerous long cliffs, called scarps, believed to have formed when the planet cooled Link to formation of a scarp

15 Mercury is not hospitable for Human Life Mercury s temperature range is the most extreme in the solar system Mercury s slow 58 Earth day rotation and the lack of an appreciable atmosphere means temperatures vary enormously from one side of the planet to the other. Daytime with the Sun overhead reaches 700K (or 800 F) Midnight with the Sun completely obscured is 100K (or F) Earth typically has temperature differences between day and night of about 11K (or 20 F)

16 Mercury Fast Facts Mercury has a dry dusty surface The surface of Mercury is much like our Moon Mercury has almost no atmosphere Mercury has wild temperature swings Mercury has no moons

17 Venus The surface of Venus is completely hidden beneath permanent cloud cover

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19 Mercury is called Evening Star Why would it be called this? Although it is 0.723AU from the Sun, to us it always appears close to the Sun

20 Venus Atmosphere is 96% CO 2 and 4% N 2 Venus has dropplets of concentrated sulfuric acid in its clouds The atmospheric pressure on Venus is 90 times that of Earth Temperature is 750K much higher than Mercury daytime AND nightime. Why? caused by the greenhouse effect

21 The greenhouse effect heats Venus s surface

22 We see dramatic increases in both pressure and temperature as we approach the surface of Venus. At the surface, the temperature is an astounding 860 F, even hotter than Mercury.

23 The extreme heating of Venus surface is caused by the greenhouse effect The carbon dioxide in the atmosphere of Venus acts as a greenhouse, trapping the heat from the Sun underneath and the temperature rising until finally thermal equilibrium is reached when the surface is 860 F!

24 This suggests that they were formed from a large single piece of falling debris that was broken up by the Venusian atmosphere. A global view of Venus using radar images from the Magellan spacecraft The craters found on Venus tend to be in clusters.

25 Venus is covered with gently rolling hills, two continents, and numerous volcanoes

26 The Magellan spacecraft, in an orbit around Venus, was able to see through the thick clouds using radar, giving us the best view of our sister planet.

27 This false color map of Venus, equivalent to a topographical map of Earth, shows the large-scale surface features of the planet.

28 Venus fast facts Venus is about the size of Earth Venus has an atmosphere that is very thick, giving a very high atmospheric pressure On Venus it rains concentrated sulfuric acid The atmosphere is mostly CO 2, leading to a nasty greenhouse effect Venus rotates in the opposite direction of other planets Venus has no moons

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30 Mars has been the Center of Speculation about Extraterrestrial Life Early telescope images showed features which were perceived as irrigation canals. People feared an attack from Mars, like this one portrayed in The War of the Worlds.

31 Mars Atmosphere Mars has an atmosphere, but it is only times as dense as that of the Earth. It is made up of CO 2 and N 2 It is thought that Mars used to have liquid water What happened?

32 Mars as viewed from Earth

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34 Impact Craters on Mars Most of these craters are found in the Southern Hemisphere, suggesting that the northern vastness has been resurfaced.

35 Like Earth, Mars has polar ice caps that grow and shrink with the changing seasons. Unlike Earth, the polar ice caps are not water but frozen carbon dioxide or what we know as dry ice.

36 Martian Seasons Mars is tilted on its axis by (nearly the same as Earth) and the hemispheres experience seasons that can be observed by examining the polar caps. Large ice cap made mostly of frozen carbon dioxide (dry ice) The dry ice melts, leaving a much smaller polar cap

37 Enormous shield volcanoes Valles Marineris is many times larger than the Grand Canyon. On Earth is would stretch from NY to LA

38 Topographical Map of Mars

39 Olympus Mons - the largest volcano in the solar system has a base larger than the state of Colorado

40 The Martian surface also has some unusual features Apparent face on the Martian surface 22 years later, with improved technology the feature looks more natural

41 Surface features indicate that water once flowed on Mars Ohio River valley on Earth River channels on Mars

42 Surface features believed to be ancient waterways A dried riverbed An ancient lake Sedimentation

43 Viking I Lander Picture from 1976 The red color comes form oxidized iron (rust)

44 1999 Picture from the Mars Pathfinder Lander - Sagan Station Note the remotecontrol rover, Sojourner, next to a Martian rock

45 Martian air is thin and often filled with dust Mars thin atmosphere is 95% CO 2 Mars atmospheric pressure is about 1% as high as Earth s Mars coldest temperatures occur at the poles at about 160K (-170 F) Typical Mars temperatures range between 50 F and -80 F Dust storms and dirt devils form on Mars

46 The Martian meteorite found in Antarctica has not provided conclusive evidence about life on Mars

47 Mars two moons, Phobos and Deimos, look more like potatoes than spheres

48 Mars fast Facts Mars has an atmosphere, but it is only <1% of Earth s Mars is dry, but used to have water Mars is colder than Earth Mars poles are so cold, the polar caps are dry ice Mars is a little smaller than Earth The Red color is due to oxidized iron (rust)

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50 Part 2: The Outer Planets also called Jovian Planets Gas planets are big balls of gas, they are held together by gravity, but they don t have a solid surface.

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53 Jupiter s clouds move in east-west bands Reddish-colored belts alternate with white-colored zones.

54 Against the background of zones and belts, turbulent swirling cloud patterns, called white and brown ovals, form. The Great Red Spot is a huge typhoon-like storm of swirling gasses that has lasted for at least 300 years and in which two Earths could fit side to side.

55 Jupiter is a called a gas giant. It is called this because it is made up of mostly gas. It is thought to only have a small solid surface. You could not stand on Jupiter because there is nothing to stand on. Jupiter is a long way from the Sun. The average temperature of its surface clouds is - 108⁰C (-162⁰F)

56 Jupiter has rings too! These 6 pictures were taken from Earth (Hawaii) in the IR spectrum of Jupiter s rings which are mostly made of small rocks

57 Jupiter has 63 moons, so many some of them have not even been named yet! These are some of the big ones. These are the ones Galileo saw in

58 Europa Europa houses liquid water under its icy surface. Scars on Europa s surface are believed to be caused by rising warmed ice.

59 Ganymede Ganymede, the largest satellite in the solar system, is even larger than Mercury. These images of Ganymede s largest feature, a huge, dark, circular region called Galileo Regio, show deep furrows in the moon s icy crust.

60 Jupiter fast facts Jupiter is 318 times as massive as Earth Jupiter has a diameter ~11 larger then Earth, this doesn t seem like a lot until you see a scale diagram The density of Jupiter is only 0.24 Earth density, Earth would float on Jupiter! The Earth could float on Jupiter because it doesn t have a solid surface! Although the Jupiter is so much, much more massive, it is also larger than Earth, its gravity is only 2.4 times as great Jupiter has rings made of mostly rocks

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62 Saturn, like Jupiter, has bands of belts and zones There is much less contrast between the belts and zones on Saturn than on Jupiter. Also, there is very little swirling structure in Saturn s clouds. It s cold! In contrast to Jupiter, Saturn s rings are made almost entirely of water ice

63 Comparison of Jupiter s and Saturn s Atmospheres

64 The interiors of Jupiter and Saturn are similar in structure. However, with less mass, Saturn does not convert as much of its hydrogen into liquid. (On both planets, the hydrogen is under such intense pressure that it forms metallic hydrogen. Metallic hydrogen is degenerate matter, which means it is so compressed that the spacing between the nucleus an the electrons is no longer spaced like we conceive of it on Earth)

65 Our view of Saturn s rings during its 30-year revolution around the Sun At some points in its orbit, we see the full face of the rings, and sometimes the rings disappear when we see them edge-on.

66 Saturn has Many Diverse Moons MINAS ENCELADUS TEHY S Saturn has 60 moons, many recently found, one Titan, is the 2 nd largest in the solar system DIONE RHEA

67 SATURN S MOONS IAPETUS PHOEB E Titan has an atmosphere three times thicker than that of Earth. It is composed of nitrogen, methane and a variety of carbon-hydrogen compounds called hydrocarbons.

68 Saturn Fast Facts Saturn has the most distinct rings of any planet in out solar system Saturn s rings are made up mostly of water ice Saturn like Jupiter is a Gas Giant and has no Solid surface Saturn is even colder than Jupiter Saturn has a diameter ~9 times larger than Earth and is 95 times more massive Like Jupiter, Saturn is much more massive than Earth, but the gravity is less,.91!

69 Uranus and Neptune are Comparable in Size EARTH ON THE SAME SCALE URANUS NEPTUNE

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71 Uranus name is Dirty Uranus can be pronounced two ways, both are equally right according to Universe Today Your anus Or Urine es Either one should have been thought out better by for us English speakers by the guy who named it Sir William Herschel

72 The Uranus axis of rotation is tilted on its side, making seasonal changes drastic.

73 The interiors of Uranus and Neptune are both believed to have the same layers.

74 The Moons and Rings of Uranus The rings of Uranus are much darker than those of Saturn. There are many fine dust particles between the main rings. Uranus has 27 known moons named after Shakespeare and Alexander Pope Characters The moon Miranda s patchwork surface suggests that huge chunks of rocks and ice came back together after a huge impact.

75 Neptune s Atmosphere Ultraviolet images reveal a band-like structure similar to Jupiter and Saturn. But it is really cold out here. The Great Dark Spot was a surprising find on a planet where it was thought that temperatures were too cold to sustain such storms.

76 Like Uranus, Neptune is Surrounded by Thin, Dark Rings

77 Neptune s moon Triton has a retrograde orbit around the planet, suggesting it was captured by Neptune. A possible frozen water ice lake

78 Uranus and Neptune Fast Facts These guys are gas giants They are very cold Both are blue and have faint rings Both are thought to have lots of water The water is not what makes them blue

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80 Before we get to Pluto, we need to make life a little Easier Here is a mnemonic to help remember the order to the planets (plus Pluto) 1. My very easy method just set up nine planets 2. My very excellent Mother Just served us nine Pizzas 3. My very educated mother just showed us nine planets

81 Pluto was Discovered as it Moved against the Background of Stars Pluto s moon Charon was originally thought to be a defect in the images of Pluto.

82 Pluto and Charon are about the same size. They are locked in a mutual synchronous orbit in which the same sides of Pluto and Charon always face each other. These images from the Hubble Space Telescope are the best we have of Pluto. They were released in Feb 2010 and show that Pluto has had a dramatic change in surface color.

83 Pluto s downfall In 2006 Pluto was downgraded from a planed to a Plutoid or Dwarf Planet This was because Many other objects of greater mass are being discovered in out solar system Pluto has does not orbit in the same plane as the other planets Bye Bye Pluto

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85 WHAT DID YOU THINK? Is Jupiter a failed star? No. Jupiter has 75 times too little mass to shine as a star. What is Jupiter s Great Red Spot? A long-lived, oval cloud circulation similar to a hurricane on Earth. Does Jupiter have continents and oceans? No. The only solid matter in Jupiter is its core.

86 WHAT DID YOU THINK? Is Saturn the only planet with rings? No. Jupiter, Uranus and Neptune also have rings. Are the rings of Saturn solid? No. The rings are composed of thin, closely spaced ringlets consisting of particles of ice and ice-coated rocks. Do all moons rise and set as seen from their respective planets? No. The one exception is Pluto s moon Charon, which remains over the same place on Pluto at all times.

87 What did you think? Is the temperature on Mercury, the closest planet to the Sun, higher than the temperature on Earth? The temperature on the daytime side of Mercury is much higher than on Earth, but the temperature on the nighttime side of Mercury is much lower than on Earth because Mercury rotates so slowly and has little atmosphere to retain heat. What is the composition of the clouds surrounding Venus? The clouds are composed primarily of sulfuric acid. Does Mars have surface liquid water today? No, but there are strong indications that it had liquid water in the distant past. Is life known to exist on Mars today? No life has yet been discovered on Mars.

88 Self-Check 1: Compare and contrast the atmospheres of the terrestrial planets in terms of temperature, pressure, and chemical composition. 2: List the properties that Mercury has in common with the other terrestrial planets and with the Moon. 3: Compare and contrast the surfaces of Mercury, Mars, and Venus with that of the Earth in terms of geologic structures and evidence regarding tectonic activity. 4: Describe plausible explanations for the absence of water vapor in the Venusian and Martian atmospheres.

89 Self-Check 6: Discuss the evidence for the existence of water on Mars surface in the past and the location and form of that water today. 7: Discuss the reasons for what we can see when we look at a planet from outer space, for example, earth has got distinct shapes that vary in color and the rest is blue.