Introductory AstrSolar System
Introductory AstrSolar System ASTR 111
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ASTR 111 003 Fall 2006 Lecture 14 Dec 4 2006 Introduction To Modern Astronomy Final Review Final exam 730 PM to 1015 PM on Dec 182006 100 multiplechoice questions 17 chapters from Chap 1 to Chap 17 For each chapter all sections are covered except those explicitly excluded For each chapter all boxes are excluded except those explicitly included Chap 1 Astronomy and the Universe 8 sections excluding 12 13 14 18 11 Scientific methods hypothesis model theory and laws of physics 15 Angular measure angular diameter angular size angular distance 16 Powersoften notation 17 Units of astronomical distances AU light year parsec Chap 2 Known the Heavens 8 sections excluding 26 28 covering box 21 and box 22 21 Ancient civilization positional astronomy 22 Constellations 23 Diurnal motion of stars Earth rotation Annual motion of stars Earth orbital motion Polaris 24 Celestial sphere celestial equator celestial poles zenith Box 21 celestial coordinates right ascension declination 25 Seasons tilt of Earth s axis of rotation ecliptic plane two reasons of why summer is hotter or winter is colder equinoxes vernal and autumn solstices summer and winter Sun s daily path 27 Timekeeping meridian noon apparent solar day mean sun mean solar day time zone universal time Box 22 sidereal time sidereal day Chap 3 Eclipses and the Motion of the Moon 6 sections excluding 36 31 Phases of the Moon new waxing crescent first quarter waxing gibbous full waning gibbous third quarter waning crescent and new the cause of the phases 32 Synchronous rotation of Moon synodic month 295 days sidereal month 273 days 33 Solar and lunar eclipses causes and configurations 34 Lunar eclipses umbra penumbra totality 35 Solar eclipses eclipse path totality Chap 4 Gravitation and the Waltz of the Planets 8 sections excluding 43 41 Ancient geocentric models direct motion retrograde motion of planets Ptolemaic systems cycles on cycles deferent epicycle 42 Heliocentric model of Copernicus explanation of retrograde motion planetary configuration Inferior planets elongation evening stars morning stars superior planets conjunction opposition synodic period sidereal period of planets 44 Kepler s three laws of planetary motion first law of shape of orbit second law of orbital speed perihelion aphelion third law of orbital period and size P2a3 45 Galileo s usage of telescope phases of Venus 46 Newton s three laws of motion first law of inertial second law of force Fma third law of action and reaction 47 Newton s law on universal gravitation orbital motion caused by gravitational force conic sections 48 Tidal force high tide low tide spring tide neap tide Chap 5 The Nature of Light 9 sections all covered box 51 and box 55 51 Speed of light 52 Wave property of light Electromagnetic radiation different types of electromagnetic radiation wavelength frequency color 53 Blackbody Blackbody radiation Box 51 three temperature scales 54 V en s law on wavelength of maximum emission Stefan Boltzmann s law on total energy of blackbody radiation 55 Dual properties of light particle and wave 56 Spectral lines Kirchhoff s laws on spectrum continuous spectrum emission line spectrum and absorption line spectrum 57 Structure of atom Box 55 periodic table 58 Bohr s model of atom orbit and energy level emission absorption 59 Doppler effect red shift and blue shift Chap 6 Optics and Telescopes 7 sections excluding 64 66 61 Refraction Refraction telescope focal point lightgathering power magnifying power 62 Reflection telescope objective mirror 63 Angular resolution diffraction limit seeing 65 Spectrograph grating 67 Telescope in orbit Optical window radio window advantages in orbit Chap 7 Comparative Planetology I Our Solar System 8 sections excluding 73 78 71 Solar system Terrestrial planets versus Jovian planets in size mass density and composition 72 Seven large satellites 74 Chemical composition Light elements heavy elements lces in the solar system 75 Asteroids comets 76 lmpact craters meteoroids geologic activity internal heat 77 Magnetic field of planets core of conducting fluid dynamo Chap 8 Comparative Planetology II the Origin of Our Solar System 6 sections excluding 86 81 Requirements of solar system model 82 Abundance of Chemical elements Origins of H and He and heavy elements interstellar medium 83 Solar system age radioactive agedating 84 Solar nebula hypothesis protosun 85 Protoplanetary disk condensation temperature ice particles planetesimals protoplanets Chap 9 The Living Earth all 7 sections 91 Active Earth Three sources of energy Greenhouse effect Greenhouse gas 92 Earth s interior structure crust mantle and core outer and inner cores seismic waves 93 Plate tectonics Pangaea Asthenosphere lithosphere Seafloor spreading subduction Earthquake 94 Earth s magnetosphere solar wind 95 Earth s atmosphere Composition Nitrogen and Oxygen Effects of living organism Photosynthesis and oxygen 96 Temperature profiles troposphere and convection stratosphere and ozone 97 Earth s biosphere Global warming Ozone hole Chap 10 Our Barren Moon 5 sections excluding 104 101 Surface Craters Terrae Maria 102 Manned exploration 103 Interior No plate tectonics 105 Formation Collisionejection theory Tidal force Chap 11 Mercury 4 sections 111 Difficulty in observing Mercury 112 Rotation 32 spinorbit coupling 113 Surface No plate tectonics No atmosphere 114 Interior Large core Chap 12 Venus 6 sections 121 Morning Star Evening Star Elongation 122 Retrograde rotation of Venus 123 Thick atmosphere High temperature Sulfuric acid clouds 124 Hotspot volcanism Clouds 125 Climate evolution Venus versus Earth Recycle of greenhouse gases Runaway greenhouse effect 126 Surface Volcanism and Interior no plate tectonics Chap 13 Mars 8 sections excluding 136 137 and 138 131 Best observation of Mars opposition 132 Illusion of seasonal color changes Canal illusion 133 Surface Craters Volcanoes Olympus Mons Dichotomy southern highlands versus northern lowlands 134 Water on Mars Polar ice caps Frozen water 135 Climate evolution Atmosphere Runaway icehouse effect Frozen water Locked carbon dioxide Chap 14 Jupiter and Saturn 12 sections excluding 145 14814111412 141 Orbital motion opposition Cloudtop Dark belts Light Zones Great Red Spot 142 Differential rotation of Jupiter and Saturn 143 Atmosphere Composition hydrogen and helium Saturn s helium deficiency Great Red Spot 144 Energy of atmospheric motion Internal energy source Temperature gradient 146 Oblateness Core lnternal structure of Jupiter and Saturn 147 Magnetic field Liquid metallic hydrogen 149 Saturn s rings Rings and gaps 1410 Ring s composition Ring particles Roche Limit Chap 15 Satellites of Jupiter and Saturn 10 sections excluding 155 157 1510 151 Jupiter s Galilean satellites lo Europe Ganymede Callisto Synchronous rotations 152 Relative density and composition of the four Galilean satellites 153 Origin of the Galilean satellites Jovian nebula 154 lo Volcanoes Tidal heating 156 Europe World of water ice Geological activity Tidal heating 158 Titan Atmosphere and appearance of Titan 159 Jupiter s small moons Capture of asteroids Chap 16 Uranus Neptune and Pluto 9 sections excluding 165 166 167 168 161 Chance discovery of Uranus Predicted discovery of Neptune 162 Uranus s atmosphere High concentration of Methane color Unusual rotation axis Exaggerated seasonalchange 163 Neptune s atmosphere Dynamic atmosphere Great Dark Spot Internal heat Gravitational contracting 164 Internal structure of Uranus and Neptune rocky core liquid waterammonia liquid hydrogenhelium atmosphere 169 Pluto Charon Kuiper Belt Pluto not a planet any more Note In class I went over problems 17 and 20 Here is some details of the diagram that I put on the chalkboard l7In Figure 2 what happens to beam A when it enters the glass It continues straight It bends up It bends down It re ects back It re ects up See the following gure or the lecture notes to see how to zoom in on a surface and then use the principles of optics to tell you which way the light will bend 3358 Line A bends towardthe normal normal When a light ray goes from air into glass or water it bends toward the normal 18In Figure 2 what happens to beam C when it arrives at the glass a It bends down and to the right b It re ects up and to the left c Both of the above 1 Both of the below e It bends up and to the right i It bends down and to the right l9Does any of the light from Beam A in Figure 2 get re ected a Yes down and to the left b Yes up and to the right c Yes up and to the left 1 No 20 In Figure 2 if the light area represents glass and the dark area represents air what happens to beam A when it enters the air from the glass beam A is still going from left to right a Continues straight b Bends up c Bends down 1 Re ects along same direction ASTR 111 003 Fall 2007 Lecture 01 Aug 27 2007 Introduction To Modern Astronomy I Solar System Introducing Astronomy JCM Astronomy and the Universe chap 16 Ch2 Knowmg the Heavens Ch3 Eclipses and Planets and Moons the Motion of the Moon chap 715 Ch4 Gravitation and the Waltz of the Planets Ch5 The Nature of Light Chap 16 our Sun Ch6 Optics and Telescope Chap 28 Search for Extraterrestrial life Highlights A total lunar eclipse Tuesday morning Aug 28 2007 EDT PDT Partial eclipse begins 451 AM 151 AM Total eclipse begins 552 AM 252 AM Total eclipse ends 423 AM Partial eclipse end 524 AM lIGoogle Earth searches the sky Astronomy Picture of the Day 20070827 Huge Void in Distant Universe Today s Sun 20070827 NSGISDUP MSH s r A J 0 s Lcngf tuHPr39m lEg39EIIH39nIJIer Astronomy and the Universe Chaptr One Scientific Methods Scientific Method based on observation logic and skepticism Hypothesis a collection of ideas that seems to explain a phenomenon Model hypotheses that have withstood observational or experimental tests Theory a body of related hypotheses can be pieced together into a self consistent description of nature Laws of Physics theories that accurately describe the workings of physical reality have stood the test of time and been shown to have great and general validity Example Theory Earth and planets orbit the Sun due to the Sun s gravitational attraction Formation of Solar S stem Mercury Venus I Earth J upm Mars Uranus Neptune Th Sun and Planet to Shale By exploring the planets astronomers uncover clues about the formation of the solar system Terrestrial and Jovian Planets Meteorites 456 billion years Solar nebula Evolution of Stars 4 x I I 3 3tl elrl t ijgn yme Our JLJIJ Jud 1 JUL A star has a full life cycle be born evolve and die Theme L dear feasibn thQHJb Origin and Fate of the universe Galaxies are flying away from each other Expanding universe Big bang theory Angular Measure Denote position and size of astronomical object degree the basic unit of angular measure One entire cycle is 360 Angular diameter or angular size The Moon is 12 and also the angular size of the Sun Complete circle r o 939 Angular Measure Angular distance If you draw lines from your eye to each of two stars the angle between these lines is the angular distance Angular Measure The adult human hand held at arm s length provides a means of estimating angles About 10 for the fist About 1 for the finger Angular Measure Subdivide one degree into 60 arcminutes minutes of arc abbreviated as 60 arcmin or 6039 Subdivide one arcminute into 60 arcseconds seconds of arc abbreviated as 60 arcsec or 60 1 60 arcmin 6039 139 60 arcsec 60 For example Moon O5 30 arcmin or 1800 arcsec Saturn 20 arcsec A star much less than 1 arcsec can not be resolved by any telescopes Angular Measure Small angle formula D linear size of an object d distance to the object 0i angular size of the object in arcsec D Cl cl 206265 If same linear size the more distant the object the smaller the angular size If same angular size the more distant the object the greater its actual linear size Size of a proton Size of an atom gt Size of a virus Size ofa human Diameter of the Earth gt Diameter of the Sun gt Distance from gt Earth to Sun Distance to the nearest gt star beyond the Sun Dlameter of gt the Galaxy Size of the observable universe 1010 1015 102039 1025 Powersof ten notation Powersof ten notation I1O Number 10 is multiplied n times 105 1OX1OX1OX1OX1O 1039 number 10 is divided n times 105110X11OX11OX11OX11O Example Earth diameter 128 X 104 km Sun s diameter 139 X 106 km SunEarth distance 150 X 108 km One light year 946 X 1012 km One year 316 X 107 s Mass of the Sun 199 X 1030 kg Mass of Proton 167 X 103927 kg Units of Astronomical Distances Astronomical Unit AU One AU is the average distance between Earth and Sun 1496 X 108 km or 9296 million miles Jupiter 52 AU from the Sun Light Year ly One ly is the distance light can travel in one year at a speed of about 3 x 105 kms or 186000 miless 946 X 1012 km or 63240 AU Pr oxima Centauri the nearest star 42 ly Parsec pc the distance at which 1 AU subtends an angle of 1 arcsec 1 pc 309 gtlt1013 km 326 ly Milky Way galaxy 50 kpc Units of Astronomical Distances 1AU X W Earth39s orbit Distance 1 parsec 326 lightyearsi Angle 1 arcsec 1 At a distance of 1 parsec a length of 1 AU subtends an angle of 1 arcsec V Observer Final Notes on Chap 1 There are 8 sections Section 1 to 7 are studied There are 3 boxes Box 1 and 2 are studied Jupiter and Saturn Lords of the Planets Chapter Twelve ASTR 111 003 Fall 2007 Lecture 11 Nov 12 2007 Introduction To Modern Astronomy I Solar System Introducing Astronomy chap 15 Ch7 Comparative Planetology Ch8 Comparative Planetology Ch9 The Living Earth Ch10 Our Barren Moon panets and Moons Ch11 Mercury Venus and Mars chap 715 Ch12 Jupiter and Saturn Ch13 Satellites of Jupiter amp Saturn Sun and Life Highlights Ch14 Uranus Neptune and Beyond Chap 16 amp 28 Ch15 Vagabonds of Solar System MW My Average distance from Sun Maximum distance from Sun Minimum distance from Sun Eccentriciiy of orbit Average orbital speed Orbital period Rotation period inclinaiion of equator to urbit inclination of orbit to ecliptic Diameter Mass Average density Escape speed Surlace gravity Earth 1 Albedo Average temperature at cluudiaps Atmospheric composition by number of molecules Largest Planet Jupiter Data lvpim 5203 AU 7783 X 108 km 5455 AU 81 50 X 1 08 km 19950 AU 7408 X 103 km 0048 131 kms ill 86 years 9quot 50 28s equatorial 9quot 55m 295 internal 312 1 30 142381 km 11209 Earth diameters equatorial 1 33708 km 1G482 Earth diameters paler 1899 X 1027 kg 3178 Earth masses 1326 kgm3 602 kms 236 165 K 862 hydragen Hz 136 helium He 02 methane Ci1h ammonia Nil13 water vapor HEB and other gases Saturn Da a Saturn Data table 14 2 Average distance from Sun 9572 AU 1432 x 109 km Maximum distance from Sun 10061 AU 1508 x 3 109 km 9063 AU 1356 X109 km Minimum distance from Sun Eccentricity oi orbit Average orbital speed 96 kms Orbital period 2937 years Rotation period 10h 1339 59s equatorial mh 3939quot 255 internal Inclination of equator to orbit 2673 Inclination of orbit to ecliptic 248 Diameter 120536 km SAAB Earth diameters equatorial 108728 km 3523 Earth diameters polar Mass 5685 x 125 kg 9516 Earth masses Average density 687 kgm3 Escape speed 355 kms Suriace gravity Earth 1 092 Albedo 046 Average temperature at cloudtops 430 C 292 F 93 K Atmospheric composition 963 hydrogen Hz 33 helium He by number of molecules 014 methane CHA ammonia N143 water vapor H20 and other gases l M nifice 1 Rings Orbital Motion Best viewed at opposition Jupiter orbital period 12 years distance 52 AU Jupiter moves across the zodiac at the rate of one constellation per year Jupiter synodic period 13 months oppositions of Jupiter occur at intervals of about 13 months Saturn orbital period 30 years distance 96 AU Saturn s oppositions occur at intervals of about one year and two weeks Zones lightcolored Apparent Views Elicolored The visible surfaces of Jupiter and Saturn are actually the tops of their Clouds The rapid rotation of the planets WM 10 hours twists the Clouds 5 into dark belts and light zones that run parallel to the equator The Great Red Spot in Jupiter is a longlived stable storm system that has lasted for at colored least 300 hundred years V Shadow of Mimas a moon of Saturn Differential Rotation Differential rotation for Jovian planets Equatorial regions rotate faster than polar regions Jupiter The equatorial region rotates at 9 hours 50 minutes The polar region rotates at 9 hours 55 minutes Saturn The equatorial region rotates at 10 hours 13 minutes The polar region rotates at 10 hours 39 minutes Solid rotation for terrestrial planets Differential rotation typifies Jupiter and Sat m Particles at different location 39 the fluid take different lengths 0 time to complete one rotation Atmosphere Composition Similar to that of the Sun from the nebula Jupiter s atmosphere by the number of molecules is 862 hydrogen H2 136 helium He 02 methane CH4 ammonia NH3 and water vapor H20 Saturn s atmosphere by the number of molecules is 963 hydrogen Hz 33 helium He 04 methane CH4 ammonia NH3 and water vapor H20 Compared with Jupiter Saturn has a serious helium deficiency in the atmosphere At Saturn s low temperature 180 C at cloudtop helium gas forms droplets and falls deeper into the planet Jupiter s temperature is relatively warmer 108 C at cloudtop helium does not yet form rain droplets Atmosphere ActIVIty Great Red Spot Brown ovals and White ovals are storm systems with circular wind Different colors due to seeing clouds at different height having different temperature eg brown seeing deeper anH1ernhEmis hale Sou 1em hen s hale fl Emu npzmcd Mm 0an pmd plumes Atmosphere Great Red Spot Winds within the Great Red Spot circulate counterclockwise J 39 20000 km 7 1 l quot 77 1quot 3939 r g l 3 I r I l Winds on the south side ofthe Great Red Spot I l flow eastward H I Winds on the north side of the Great Red Spot flow westwar t l Earth s diameter The great red spot was first seen in 1664 but may be much older It is larger than the size of the Earth The spot rotates counterclockwise with a period of about 6 days Winds on the north flow westward Winds on the south flow eastward The spot is red because it is made of clouds at relatively high altitude Atmosphere Activity Storm systems under development J a gtltNcw storm Great Red Spot Jupiter s new storm Saturn s new Storm Gemini North Teescope Cassini spacecraft infrared Internal Heat Weather patterns in Earth s atmosphere are powered by suanht Weather patterns in Jupiter and Saturn are powered mainly by internal heat as well as sunlight Jupiter emits twice as much energy as from Sunlight The internal energy comes from the thermal energy left after the initial creation of planets Because of the large size Jupiter and Saturn has retained substantial thermal energy even after billions of years As the result of the continuous heat flow from below the temperature of the atmosphere increases with increasing depth causing strong updown convection Coupled with fast rotation convection flows in the atmosphere create a global pattern of eastward and westward zonal winds eg 500 kms Zonal wind changes direction at the boundary of light zones and dark belts Internal Heat a Jupiter s atmosphere b Saturn s atmosphere 200 39The temperature 0f JSaturn hasower the atmospheres 3333253525 increases with 10 M Saturn has weaker surface gravity than Jupiter so its cloud layers are more increasing depth 39Very steeper NH3 CIOUds 7 spread out changes for Jupiter quotquot4SHC39 quot 39S l 400 H20 clouds r L 7 NH clouds The atmosphere may have three layers of clouds Jupiter and Saturn have no 393 solid surface NH3ammonia NH4SH clouds quot200 NH4SH ammonium 39 hydrosulfide H20 water H rlnurl l o N no I l I Temperature 0 Temperature C Altitude km above 100millibar level 200 160 Internal Heat Dark belts are regions we can see into the atmosphere s lower levels Dark belts appear brighter in infrared images thus warmer in temperature and deeper in altitude White zones and Great Red Spots are clouds at higher altitude where temperature is lower Zones appear dark because their high altitude clouds are cold Belts appear bright because we see to warmer depths of the atmosphere 4 The Great Red Spot region of cool highaltitude clouds A appears dark Great Red Spot a Visiblelight image 3 Infrared image Galileo Probe The mission continued for 58 minutes The probe reached 200 km below the Jupiter s upper cloud layer I At this depth temperature has increased to 152 C and pressure to 24 ATM Constant wind at 650 kms throughout the descent indicating the energy source is internal heat instead solar heating Interior Oblateness and cores Oblateness sphere is flattened at the pole Jupiter oblateness 65 Diameter across the equator is 65 larger than its diameter from pole to pole Saturn oblateness 98 Earth 03 The oblateness depends on 1 planet s rotation rate and 2 the mass distribution over its volume which can be used to infer the properties of the core Interior Oblateness and cores Jupiter has a rocky inner core It is surrounded by an outer core of liquid ices water ammonia methane A thick mantle of helium and liquid metallic hydrogen An outermost gas layer composed a Jupiter 523239 22 E Z39IL39illcail fd39EZiei quot Lquot l2ll l 9 quot primarily of ordinary hydrogen and helium Saturn s internal structure is similar a to that of Jupiter but its core makes up a larger fraction of its volume and its liquid metallic hydrogen mantle is 39 2 quot b saturn shallower than that of Jupiter Magnetic Field and Metallic Hydrogen Jupiter and Saturn have strong magnetic fields which should be generated by motion of an electrically conducting fluids in the interior Liquid metallic hydrogen instead of liquid iron in the Earth plays the role hydrogen becomes a liquid metal when pressure exceeds 14 million atmosphere Saturn39s aurorae in Jupiter b Saturn Saturn s Rings Saturn is circled by a system of thin broad rings lying in the plane of the planet s equator Largest rings in the system A ring B ring and C ring Cassini division is a gap of 4500 km separating A and B ring 274000 km 244000 km 235000 km 1 34000 km 149000 km 2 I 0536km I l Cassini division Saturn s Rings The ring appears and disappears over years The system is tilted away from the plane of Saturn s orbit which causes the rings to be seen at various angles by an Earthbased observer over the course of a Saturnian year The ring disappears when seen edgeon Rings seen edgeon 1203001mov Top rings seen Rings seen edgeon Saturn s Rings Roche Limit Saturn s rings could not be solid sheet of matter Gravitational tidal force would tear it apart Tidal force tends to keep particles separate Roche limit at this distance from a planet s center the disruptive tidal force is just as strong as the gravitational force between particles Inside Roche limit the tidal force overwhelms the gravitational force Particles can not accrete to form a larger body Instead they tend to spread out into a ring around the planet For a planet Roche limit is 24 R planet radius 12CC1SW1c Saturn s Ring Composition Saturn s rings are composed of numerous particles The ring particles are ice fragment or icecoated rocks These particles produced thousands of narrow closely spaced ringlets Inner particles move faster than outer particles in complete agreement with Kepler s third law The particles are mostly 10 cm snowball size in size ranging from 1 cm pebble size to 5 m cross boulder size Most of its rings exist inside the Roche limit of Saturn Cassini division Eane gap F ring Saturn s Rings The rings are seen as sunlight is reflected by the icy ring particles The ring pattern is affected by the gravitational effects of nearby moons Panama Ianus and Epimemms Tethys Calypso Prometht s both mm m samc orbit and Telesto 311 At s Mm Emehdm lhrce share the Pan same orbit B Cassmi Bucks amen gap Final Notes on Chap 12 There are 11 sections in total The following sections are not covered 1211 satellites affect the structure of the ring Red Planet Mars Thirteen ASTR111 003 Lecture 11 Nov 13 2006 Fall 2006 Introduction To Modern Astronomy Introducing Astronomy Chap 16 Planets and Moons Chap 717 Ch7 Comparative Planetology I Ch8 Comparative Planetology II Ch9 The Living Earth Cth Our Barren Moon Chl 1 SunScorched Mercury Ch12 Cloudcovered Venus Ch13 Red Planet Mars Ch14 Jupiter and Saturn Ch15 Satellites of Jup amp Saturn Ch16 Outer World Ch17 Vagabonds of Solar System Guiding Questions When is the best to see Mars in the night sky Why was it once thought that there are canals on Mars How are the northern and southern hemispheres of Mars different from each other What is the evidence that there was once liquid water on Mars Why is the Martian atmosphere so thin What have we learned about Mars by sending spacecraft to land on its surface What causes the seasonal color changes on Mars As seen from Mars how do the Martian moons move across the sky Average disiance from Sun Maximum distance mm Sun Ecceniri y o orhii Average orbital speed Orbi ial period Inc inalion of equator i0 0 Enc ination of 0 x10 ectipiic Mass Average densii Escape speed Surface graviiy Eariiz beds Surface temperatures Atmospheric cumposiiion by number of molecules MEAL 1521 AU 2279 x10 km 1666 A39J 2492 lt 10quot km 1381 Pquot 2067 x 30 km 010523 241 Ians 68598 days 788 24quot 3739 225 2519quot 135 679 km 2 0533 Earm diameier uh mass 3931 kgm3 50 kms 038 0515 Maximum 20quotquot 76 283 K Mean 53 C63 220 K Mi Linn 440 C 22 F 133 K 953 carbon dioxide 602 2 0o niirogen NZ 003 waier vafmr I 2 other gases Earthbased observations The best Earthbased views of Mars are obtained when Mars is simultaneously at 1 opposition and 2 near perihelion 2001 Orbit of ltMar3 At favorable opposition the Favorable opposition Mars is at opposition Unfavorableo osition Ea rth39 M a near penhellon I Mars is at oppgs39ition r near aphelion distance can be Ju39v Sun as small as E a Se t 037 AU and quot angular diameter can be as large as 2005 November 25 arcsec 7 2007 December 24 Earthbased Observations Mars has a thin almost Cloudless atmosphere that permits a Clear view of the Surface A solar day on Mars is nearly the same length as on Earth Mars has polar caps that expand and shrink with the seasons The Martian surface undergoes seasonal color Changes Earthbased observations A few observers in 19th century reported a network of linear features called canals These observations led to many speculations about Martian life However it is proven that the canals are illusion Surface Since 1960s Mars have been regularly visited by Volcanoeson unmanned spacecraft mm and their landing modules The Martian surface has numerous craters several huge volcanoes a vast rift valley and driedup riverbeds but no canals Valles Marineris Surface Martian surface is largely covered by craters Some martial surface must be extremely ancient Syrtis Major Hellas Planitia South polar 39 g V r ice cap Small craters on topp a 9 lg ones ingli cate an old surface a Mars from the Hubble SpaceTelescope b Closeup of Sinus Sabeus region Surface Olympus Mons the largest volcano in the solar system 600 km across 24 km above the surrounding plains the scarps or cliffs 6 km high It was probably formed by hotspot volcanism magma wells up from a hot spot in a planet s mantle over a long time eg millions of years The huge size of Olympus Mons instead a chain indicates the absence of planet tectonics Surface Southern highlands versus northern lowlands dichotomy The average elevation of southern highlands is about 5 km higher than that of northern lowlands Surface in the south is relatively older because of numerous craters Surface in the north is smooth and free of craters km 8 No liquid water or rainfall on the planet s surface today Liquid water once flowed on March as evident in many surface features Eg dried riverbeds on the Martian surface Island carved by flash ood n quotIslandsquot carved h ng ago Mastl an flash ood Water on Mars The impact that made the crater melted the ice beneath the surface causing these mud flows 7 YUty Crater 18 km across 39 Mud flow feature indicates a subsurface layer of water ice Sustained water carved outcanyons Water on Mars Gullies have formed by subsurface water Surrounding seeping out to the quotai surface ed by Wit unning dowh crater walls v Crater floor Water on Mars Mars s polar caps contain frozen water The Martian polar caps expand in winter as a thin layer of frozen carbon dioxide dry ice is deposited from the atmosphere North polar ice capfrozen C02 on top of frozen water Water on Mars Frozen water is contained in polar caps Frozen water is stored in permafrost under the Martian surface There might be enough water to cover the planet to a depth of 500 meters Percent abundance of water by mass 2 4 6 8 10 12 14 16 18 l7 V 57 7 30 h concentration of t subsurface water in the 0 egions lg concentration of 300 subsurface water in some 39 locations near the equator MLeeEA W 39 6o W 180 240 300 0 60 120 Water Measurement from Mars Odyssey Spacecraft Atmosphere The present Martian atmosphere is composed mostly of carbon dioxide The atmospheric pressure on the surface is less than 1 that of the Earth and shows seasonal variations as carbon dioxide freezes onto and evaporates from the poles Mars and Earth began with similar primordial atmosphere that evolved differently Mars has relatively weaker gravity Mars is geologically inactive Atmosphere Water and carbon dioxide molecules are broken into atoms which then escape into space thanks to the weaker gravity of the Mars This weakened the greenhouse effect and caused the temperature to drop A lower temperature caused more water vapor to condense to the surface carrying carbon dioxide This further reduced the temperature caused a runaway icehouse effect opposite to the runaway greenhouse effect occurred on Venus The remaining water is frozen underneath the surface The remaining 002 is locked in the rocks it is not recycles into the atmosphere thanks to the inactivity Atmosphere The remaining water is frozen underneath the surface The remaining 002 is locked in the rocks it is not recycles into the atmosphere thanks to the inactivity This resulted in a thin Martian atmosphere 2The weaker gravity also 1 Ultraviolet light from the sun broke some allowed carbon and water molecules apart due to the weaker gravity both hydrogen and oxygen escape nitrogen atoms to escape Escape Sunlight CloT i N e colder temperatures caused the remaining water to freeze beneath the surface 4 Carbon dioxide went into carbonate rocks and the regolith since plate tectonics is not active on Mars carbon dioxide is not recycled into the atmosphere b Mars Atmosphere Clouds are made of tiny water ice crystals as well as crystal of carbon dioxide ice dry ice OlympusMons Tharsis volcanoes Clouds Above Mars Mountains Atmosphere When temperature rises during the spring CO2 frost evaporates and trigger the dust storm September 4 2001 A planetwide dust storm now obscures the entire surface of the planet June 26 2001 Dust storms begin near the northern polar cap and near Hellas Planitia Atmosphere When temperature decreases during the winter freezing 002 adheres to water ice and dust grain in the air causing them to fall to the ground quot 394 II quot 39 in K a 0quot u39 A 1 I H 1 VT 39 v gt A v A f 1 a 3 1n t 7 i l J V 1 Qquot J Exploration Many spacecraft have been sent to study the Mars including both orbiting and landing spacecraft In 1970s Viking 1 and Viking 2 Landers In 1997 Mars Pathfinder Lander called Sojourner In 2004 Mars Exploration Rovers Spirit and Opportunity Human exploration on Mars is now under development Dish antenna MarsPath nderrover Hill1 km 06 mi away Cameras Mars Exploration Rover Mars Path nder rover 7 m Extendable arm Two generations of rovers a A rover on Mars Exploration G mp of rocks about 15 m 7 across 8 m from the camera ASTR 111 003 Fall 2007 Lecture 02 Sep 10 2007 Highlights of the Universe 397As7trrc qf t 7 7290 S P re 7 7 7AVA rg7 7 7 1 r r Y 7 p lt 71 j r 4 7 I 7 7 7 7 7 7 39 7 K 1 r 5 7 r 7 7 rquot 39 quot 7 7 v A 7 7 7 7 7 7 A 7 7 7 7 lt 7 7 v 7 l 39 739 7 39 7 v9 7 7 7 7 7 7 7 7 a 7 A 7 gt 7 7 7 4 90 5 42 5 76 1 b 6 quot 400 4 35 1 Galaxy Building Buocks 39n H bble H T 39 the Hubble Ultra Deep Field A SW c sTScuiHR u 73 NASA ESA aha N Pijksl STSCIIEDA Astronomy Picture of the Day 2007 Sep 2 Advanced Question Chap 1 037 in P18 Suppose your telescope can give you a clear view of objects and features that subtend angles of at least 2 arcsec What is the diameter in kilometers of the smallest craters you can see on the Moon
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