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A Tour Through Our Solar System “Martha visits every Monday and just stays until noon, period.” 11/15/99 Norm Herr (sample file) Only write the yellow text. The SOLAR SYSTEM • The sun • Nine planets • Lots of satellites (moons) • Many comets and asteroids 11/15/99 Norm Herr (sample file) Some Definitions • Planet: an object that travels in a path around the sun or a star. • Moon: an object that travels in a path around a planet (or an asteroid). • Revolution: The motion of one object around another. E.g. Earth revolves around the sun. • Rotation: Besides orbiting the sun, all planets spin. This is the motion around its axis. 11/15/99 Norm Herr (sample file) The Sun • 75% hydrogen and 25% helium by mass • Large enough to hold 1 million Earths! • Provides Earth with light, heat and gravity to remain in orbit 11/15/99 Norm Herr (sample file) 11/15/99 Norm Herr (sample file) This slide shows the relative sizes of the planets and sun. 11/15/99 Norm Herr (sample file) This slide shows the relative sizes of the planets. Norm Herr (sample file) 11/15/99 The Terrestrial Planets • Mercury, Venus, Earth, and Mars\ • Hard, rocky (silicate) outer parts (crust and mantle) and inner cores of Fe-Ni metal. 11/15/99 Norm Herr (sample file) • • • • 11/15/99 Orbit close to the Sun. Volcanoes, mountains, valleys. Very few moons. No rings. Norm Herr (sample file) Comparing Interiors active geology 11/15/99 Norm Herr (sample file) inactive geology MERCURY • Closest planet to sun • Orbits the Sun in 88 Earth days (revolution) • Turns on its axis every 59 days (turns 1.5 times every orbit) • One day equals 176 Earth days (rotation) • T varies from -173 to 330 °C • No atmosphere • No satellites (moons) 11/15/99 Norm Herr (sample file) Composite picture of mercury weak magnetic field large metallic core 11/15/99 Norm Herr (sample file) Welcome to Venus! • No spacesuit would save you on Venus. The air pressure is 90 times Earth’s, and the air is almost entirely carbon dioxide, with traces of various acids. Worse yet, the surface is hot enough to melt lead! • Michael A. Seeds. 11/15/99 Norm Herr (sample file) • Venus is covered in a thick blanket of white clouds thought to be made of droplets of sulphuric acid. • 17 probes have landed on its surface. 11/15/99 Norm Herr (sample file) VENUS • 2nd planet from the Sun • Third brightest object we can see in the sky • One rotation = 243 Earth days (in the opposite direction of Earth) • One revolution = 225 days Collision with planetesimal or solar tides in atmosphere reversed its direction. 11/15/99 Norm Herr (sample file) • Atmosphere 96% carbon dioxide, 3.5% nitrogen, 0.5% water vapor and acids • Atmospheric pressure is 90 times that of Earth • T = 470 ° C due to the “Greenhouse effect” caused by CO2 in atmosphere 11/15/99 Norm Herr (sample file) 2004 image of Venus from Galileo Spacecraft showing clouds! 11/15/99 Norm Herr (sample file) Hubble Telescope view Venus 11/15/99 Norm of Herr (sample file) 1999 in ultraviolet Venus Surface image from the Venera 13 spacecraft 11/15/99 Norm Herr (sample file) Radar Map of Venus – clouds have been removed. 11/15/99 Norm Herr (sample file) Venus has Craters 11/15/99 Norm Herr (sample file) Venus is Volcanic 11/15/99 Norm Herr (sample file) EARTH • 3rd planet from the Sun • period of rotation: 24 hours (1 day) • Revolution equals 365.26 days (1 year) • T = - 50 to 50 ° C • Atmosphere: nitrogen, carbon dioxide, oxygen • 1 satellite is our Moon 11/15/99 Norm Herr (sample file) 11/15/99 Norm Herr (sample Photo of the Earth taken by thefile)Apollo 13 mission Where are we? 11/15/99 Norm Herr (sample file) 11/15/99 The Earth as seen Norm from the surface of the Moon. Herr (sample file) The MOON • Orbits Earth every 28 days. • Moon turns once on its axis every 28 days! (tidal coupling) • This means that we see the same side of the moon. • Moon rocks are hardened molten rock and contain no water (unlike Earth). 11/15/99 Norm Herr (sample file) The Origin of the Moon • 4 possible theories – Fission hypothesis: a rapidly spinning Earth broke in two • What happened to all that angular momentum? • Why isn’t the moon in the same plane as Earth’s equator? – Condensation hypothesis: both the Moon and Earth condensed from the same cloud of material 11/15/99 • Should have the same composition – but they don’t Norm Herr (sample file) – Capture hypothesis: Moon formed near Mercury and was knocked over to Earth • Relies on a chain of unlikely coincidences. • Earth’s gravity couldn’t have captured it without ripping it apart. – Large-impact hypothesis: A large planetesimal collided with Earth. Material was ejected into a disk around Earth and eventually formed the Moon. • This is the currently accepted theory. 11/15/99 Norm Herr (sample file) Photos of the ‘Far side of the Moon’ 11/15/99 Norm Herr (sample file) 11/15/99“Almost full Moon”Norm taken Apollo 13 on it’s journey home. Herr by (sample file) Galileo picture of moon taken in violet, red, and near infrared 1990 11/15/99 Norm Herr (sample file) Moon 11/15/99 Norm Herr (sample file) Welcome to Mars! • Without a spacesuit, you could live only about 30 seconds on the surface of Mars. The temperature might not be too bad. On a hot summer day at noon, the temperature might reach 20°C. But the air is 96% carbon dioxide, is deadly dry, and contains almost no oxygen. 11/15/99 Norm Herr (sample file) Welcome to Mars! • Also, the air pressure at the surface of Mars is only 0.01 that at the surface of Earth. Stepping onto the surface of Mars without a space suit would be about the same as opening the door of an airplane flying at 30 000 m above Earth. (Jets fly under 12 000 m!) 11/15/99 Norm Herr (sample file) Welcome to Mars! • Because of the low atmospheric pressure, if you stepped outdoors on Mars without a space suit, your own body heat would make your blood boil! Michael A. Seeds. 11/15/99 Norm Herr (sample file) MARS • • • • • • 4th Planet from the Sun Mars is known as the Red Planet One rotation = 24 h 37 min One revolution = 687 days T = -140 to 20 ° C Atmosphere of carbon dioxide, argon and nitrogen • Two moons 11/15/99 Norm Herr (sample file) 11/15/99 Norm Herr (sample file) Mars: The Red Planet The Surface of the Red Planet Photo taken by the spacecraft rover ‘Opportunity’ in Jan. 2004 11/15/99 Norm Herr (sample file) Olympus mons – the largest volcano in the solar system! 11/15/99 Norm Herr (sample file) Martian surface as taken by the Viking Lander 11/15/99 Norm Herr (sample file) 11/15/99 Norm Herr (sample file) Landing of the Martian Land Rover 2004 Martian Land Rover – Sojourner 11/15/99 Norm Herr (sample file) Mars’ Polar Caps Frozen carbon dioxide and possibly water underneath. 11/15/99 Norm Herr (sample file) The Moons of Mars Deimos (Panic) and Phobos (Fear) Named for the horses that pulled the chariot of Ares, the Greek God of war. They are thought to be captured asteroids! 11/15/99 Norm Herr (sample file) Asteroid Belt • Asteroids are irregularly shaped, rocky objects • Located between Mars and Jupiter • Largest is 1 000 km across 11/15/99 Norm Herr (sample file) Ida – as taken by Galileo. It is estimated to be 52 km in length. 11/15/99 Norm Herr (sample file) Galileo’s Deployment 11/15/99 Norm Herr (sample file) Three Asteroids 11/15/99 Norm Herr (sample file) Ida and Its moon 11/15/99 Norm Herr (sample file) Double Asteroids 11/15/99 Norm Herr (sample file) Eros 11/15/99 Norm Herr (sample file) The Jovian Planets The “Gas Giants” • • • • • • 11/15/99 Jupiter, Saturn, Uranus, and Neptune Many times larger than terrestrial planets. Separated by enormous distances. Primarily gaseous or liquid. Have thick atmospheres. Have many moons and complex ring systems. Norm Herr (sample file) Welcome to Jupiter! • If you parachuted into Jupiter with a small rubber boat, expecting to go sailing on the liquid hydrogen ocean, you would be disappointed. Mathematical models tell us that there is no surface. Deep below the clouds, the temperature and pressure exceed the critical point for hydrogen, the temperature and pressure above which liquid hydrogen and gaseous hydrogen have the same density and are indistinguishable. 11/15/99 Norm Herr (sample file) Welcome to Jupiter! • As you parachuted down through Jupiter’s atmosphere, the temperature, pressure, and density would rise, and gradually the gas would become a fluid. You would never splash down and your rubber boat would be useless. Below the clouds of Jupiter lies the largest ocean in the solar system – and it has no surface and no waves. Michael A. Seeds 11/15/99 Norm Herr (sample file) Jupiter • Jupiter contains over 70% of the mass in the solar system outside the Sun. • It is the 5th planet from the sun and the 1st planet of the outer solar system. • Jupiter is a ball of gas and liquid (mostly hydrogen and helium). 11/15/99 Norm Herr (sample file) • • • • • 1 rotation = 10 hours long 1 revolution = almost 12 Earth years 63 satellites (moons) T = - 148 ° C Atmosphere of hydrogen, helium, and methane • Has a ring system made of three parts 11/15/99 Norm Herr (sample file) Jupiter Has A Ring The dust making up Jupiter’s ring is young and is most likely coming from neighbouring moons. 11/15/99 Norm Herr (sample file) The ring system of Jupiter and 4 of it’s moons. 11/15/99 Norm Herr (sample file) The Great Red Spot of Jupiter is 20,000 km wide which is almost twice the width of the Earth (diameter = 12,756 km) It is a giant storm which has existed for over 300 years! Note the White Oval just below the Red Spot 11/15/99 Norm is Herr 9000 (sample file) It is another storm which km wide! The Great Red Spot 11/15/99 Norm Herr (sample file) A view of Jupiter showing one of it’s moons, Io. 11/15/99 Norm Herr (sample file) Four of the major moons of Jupiter… 11/15/99 Norm Herr (sample file) Jupiter is hot Inside 11/15/99 Herr (sample file) The temperature at theNorm core is estimated to be 30 000 K. Other moons: Callisto 11/15/99 Norm Herr (sample file) Valhalla Basin, Callisto 11/15/99 Norm Herr (sample file) Ganymede 11/15/99 Norm Herr (sample file) Ganymede 11/15/99 Norm Herr (sample file) Close-up of Ganymede 11/15/99 Norm Herr (sample file) Europa 11/15/99 Norm Herr (sample file) Europa’s Icy Crust 11/15/99 Norm Herr (sample file) Io – orbits Jupiter in under 2 days! In order to hold on to Io, Jupiter must be 318 times Earth’s mass! 11/15/99 Norm Herr (sample file) Io Has Active Volcanoes 11/15/99 Norm Herr (sample file) Lava Flows on Io 11/15/99 Norm Herr (sample file) Eruption on Io 11/15/99 Norm Herr (sample file) SATURN • Rotation period 10 hours 39 min • Length of year is 29. 5 Earth years • Has a ring system made of over 1 000 separate rings! • T = - 178 °C • 56 moons 11/15/99 Norm Herr (sample file) • It has strong surface winds (500 m/sec). • Hydrogen, helium and methane make up its atmosphere. • Saturn is less dense (0.7) than water so it could float!!!. Infrared picture of Saturn taken 11/15/99 Norm Herr (sample file) in 1998 by Voyager. The rings are made up of billions of ice particles 11/15/99 Norm Herr (sample file) The ice is constantly replenished from Saturn’s icy moons. Spacecraft Voyager 11/15/99 Norm Herr (sample file) The cratered surface of Saturn’s moon Rhea looks a lot like Mercury or Earth’s Moon. It is only 1500 kilometers in diameter and has an icy crust. 11/15/99 Norm Herr (sample file) Other moons: Mimas 11/15/99 Norm Herr (sample file) Enceladus 11/15/99 Norm Herr (sample file) Tethys 11/15/99 Norm Herr (sample file) Titan 11/15/99 Norm Herr (sample file) Two views of Saturn’s largest moon, Titan. Photo on left shows a band of clouds near the N. pole. Other photo shows a blue haze of nitrogen. Titan is the only moon in the solar system with an atmosphere! 11/15/99 Norm Herr (sample file) A comparison of the size of the inner planets and the large moons. 11/15/99 Norm Herr (sample file)bigger than Mercury! Notice that Ganymede and Titan are both URANUS • • • • Uranus has 27 moons 1 rotation = 17 hours 18 min 1 revolution = 84.1 Earth years Rotates “on it’s side” with S. pole facing the Sun • T = - 216 °C 11/15/99 Norm Herr (sample file) URANUS • Orbit can take it past Pluto • Atmosphere of hydrogen, helium and methane • Has at least 12 rings made of fine dust 11/15/99 Norm Herr (sample file) Infrared photos of Uranus taken 90 minutes apart shows 11/15/99 Norm Herr (sample file)a view of the rings. movement of 7 of the moons and Photo of the gas giant Uranus… …blue colour is due to the presence of methane in the atmosphere 11/15/99 Norm Herr (sample file) Uranus from Voyager 11/15/99 Norm Herr (sample file) The Rings of Uranus 11/15/99 Norm Herr (sample file) The Moons of Uranus 11/15/99 Norm Herr (sample file) Miranda 11/15/99 Norm Herr (sample file) Rift on Miranda 11/15/99 Norm Herr (sample file) Triton 11/15/99 Norm Herr (sample file) NEPTUNE • • • • • • 1 rotation = 15 hours 40 min 1 revolution = 165 Earth years 13 moons T = - 214 °C Ring system present Atmosphere of hydrogen, helium and methane 11/15/99 Norm Herr (sample file) • The blue colour is due to the presence of methane • The Great Dark Spot was a storm that moved at 1200 km per hour • Winds around the GDS moved at 2000 km per hour! • The Scooter was an irregularly shaped cloud that traveled around the planet every 16 hours 11/15/99 Norm Herr (sample file) As seen by Voyager 2 The Great Dark Spot (GDS) and Scooter. The GDS is 6000 km wide Scooter is the white area to the lower left Below it is a smaller dark spot with a bright core. All 3 move at different speeds around the planet 11/15/99 Norm Herr (sample file) This photo shows another view of the GDS which appears to rotate counter-clockwise and is accompanied by white clouds. The Scooter and ‘small dark spot’ are also in the photo. According to the Hubble Space Telescope, the GDS has since disappeared. 11/15/99 Norm Herr (sample file) The Rings of Neptune. The black band blocks reflected light from the planet. Otherwise the rings could not be seen. 11/15/99 Norm Herr (sample file) A comparison of the Jovian planets 11/15/99 Norm Herr (sample file) PLUTO • The smallest “planet”or dwarf planet • Often the most distant object from the Sun • 1 rotation = 6.4 Earth days ( in the opposite direction of Earth) • 1 revolution = 247.7 Earth years • T = - 230 °C • 3 moons • No longer a planet ? 11/15/99 Norm Herr (sample file) PLUTO • Thin atmosphere of methane and nitrogen • Discovered in 1930 by accident. • Some astronomers believe that Pluto is not a planet but rather the largest member of the Kuiper belt. 11/15/99 Norm Herr (sample file) Pluto 11/15/99 Norm Herr (sample file) 11/15/99 Norm Herr (sample file) Pluto and the satellites orbiting him…. Notice the orbits of Pluto and Neptune….. 11/15/99 Norm Herr (sample file) An artist’s conception of the surface features of Pluto (on left) and Charon (on the right) Pluto is 2300 km in diameter, Charon is 1200 km wide. 11/15/99 Norm Herr (sample file) Pluto and it’s moon Charon Hubble telescope image at 4.4 billion km from Earth. This is the clearest image ever taken of them. They are so close together that when seen through a telescope from Earth they would look like one object. 11/15/99 Norm Herr (sample file) Beyond Pluto? • Sedna – a “new” miniplanet past Pluto – It is the coldest body in the solar system • Quaoar • Plus lots of others! 11/15/99 Norm Herr (sample file) Kuiper Belt 30 – 50 AU • Vast reservoir of icy rocks beyond Neptune’s orbit • Possibly number in the millions! • Each are thought to be half rock and half ice • On occasion a gravitational “bump” from Neptune knocks a Kuiper belt object out of orbit and sends it toward the sun forming a comet 11/15/99 Norm Herr (sample file) Oort Cloud 10 000 – 100 000 AU • Envelops the entire solar system • Consists of trillions of loose lumps of dust and gases – leftovers from the formation of the planets • Comets originate here 11/15/99 Norm Herr (sample file)