Notes Unit IV-I “Mercury & Venus” S.W.B.A.T
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Notes Unit IV-I “Mercury & Venus” Name: ____________________ S.W.B.A.T • Identify _______________ characteristics of Mercury & Venus • Understand how the two _____________ planets compare • Discuss the evolutionary ______________ of both planets Planet Mercury • Smallest, closest & _______________ planet to orbit the Sun • Heavily cratered surface resembles the _______________ • Average _______________ from the Sun .39 AU or 58 million kilometers (36 million _______________) • 2440 km in _______________ or about .38 the size of Earth • _______________ the Sun in 88 days • Spins _______________ on its axis every 59 days (sidereal period) • Surface temperature ranges from - 300oF to + 800oF (over ___________ difference!) • Only inner planet besides _______________ to have a measurable magnetic field • Inner iron core (nucleus) is very _______________ • Iron core spins _______________ an electric/magnetic field effect like _______________ • Caloris Basin – very large _______________ structure near the equator created about ____ billion years ago • One of the _______________ impact basins in the Solar System • The impact created “_______________ terrain” on the other side of Mercury (ex.’s mountains, scarps & ____________ ) • Because of Mercury’s small size it _______________ quickly helping to form the “weird” crustal terrain • Very _______________ metallic/rock crust composition • _______________ axial tilt (3o) • Highly _______________ orbit (.206 compared to Earth’s .016) • No _______________ & no (real) atmosphere • Mercury may have been _______________by a planetesimal early in its history stripping away _______________ material • This may explain why the core is so _______________ Planet Venus • .72 AU or 109 million km from the __________ • _______________ (on average) & brightest planet as seen from Earth • 6000 Km in radius or about ______ size of the Earth • One year = 225 _______________ days • One _______________ day = 243 Earth days • A Venusian day is longer than its _______________! • Rotates opposite or _______________ from all the other planets (east to west) • Most _______________ planet – 177.4o from the solar plane • Tilt may be due to a _______________ later in formation • Internal _______________ resembles Earth – core, mantle, crust • Venus was _______________ to cool down and remains hotter internally than _______________ • Planet _______________ itself roughly every 500 million years with fresh _______________ flows • Lack of eroded impact _______________ may indicate active volcanism • Currently no _______________ tectonics; no oceans (way too hot) or magnetic _______________ • Surface is relatively _______________ (500 million years old) • Thick atmosphere of CO2 – ______ times thicker than Earth’s • “_______________” greenhouse effect – trapping the Sun’s _______________ at the surface • Causes temperatures to be over _____oF – hotter than Mercury • Almost _______________ orbit - .008 eccentricity • No moons • Magellan (1989) radar _______________ over 160 volcanoes & 1000 craters on the _______________ • Venera’s (1970’s) spacecraft _______________ on the surface • Detected _______________ & thunder & returned a few pictures • Venus Express (2006 - ?) currently _______________ the planet • Discovered huge polar _______________ of unknown origin in the atmosphere 3/23/20 •Identify physical characteristics of Mercury & Venus •Understand how the two inner planets compare •Discuss the evolutionary history of Astronomy both planets •Smallest, closest & •Average distance from fastest planet to orbit the Sun .39 AU or 58 the Sun million kilometers (36 •Heavily cratered million miles) surface that •2440 km in radius or resembles the Moon about .38 (less than half) the size of Earth •Orbits the Sun in 88 days •Only inner planet besides •Spins once on its axis every 59 Earth to have a measurable days (sidereal period) magnetic field •Surface temperature ranges •Inner iron core (nucleus) is from -300oF to +800oF (over very large 1000o difference) •Iron core spins creating an electric/magnetic field effect like Earth 1 3/23/20 Earth’s Internal Structure Compared With Mercury •Caloris Basin – very large impact structure near the equator created about 4 billion years ago •One of the largest impact basins in the Solar System • The impact created “weird terrain” on the other side of Mercury (ex.’s mountains, scarps & cliffs) • Because of Mercury’s small size it cooled quickly also helping to form the “weird” crustal terrain 2 3/23/20 •Ver y dense metallic/rock crust composition •Small axial tilt (3o) •Highly eccentric orbit (.206 compared to Earth’s .016) •No moons & no (real) atmosphere Video (1:26) “Planet Mercury Facts” • Mercury may have been struck by a large planetesimal Video Animation (:43) “Messenger’s Journey To Mercury” early in its history stripping away mantle material • This may explain why the core is so large •.72 AU or 109 million km from the Sun •Closest (on average) & brightest planet as seen from Earth •6000 km in radius or about .95 size of the Earth 3 3/23/20 •Rotates opposite or •One year = 225 Earth retrograde from all the days other planets (east to •One Venusian day = 243 west) Earth days •Most tilted planet – 177.4o from the solar •A Venusian day is longer plane than its year! •Tilt may be due to a collision later in formation •Internal structure •Planet resurfaces itself roughly resembles Earth – every 500 million years with fresh core, mantle, crust lava flows •Venus was unable to •Lack of eroded impact craters may cool down and indicate active volcanism remains hotter internally than Earth •Currently no plate •Thick atmosphere of CO2 tectonics; no oceans – 100 times thicker than (way too hot) or Earth’s magnetic field •“Runaway” greenhouse effect – trapping the Sun’s •Surface is relatively heat at the surface young (500 million •Causes temperatures to years old) be over 900oF – hotter than Mercury 4 3/23/20 •Almost circular orbit - .008 eccentricity •No moons •Magellan spacecraft (1989) radar mapped over 160 volcanoes & 1000 craters on the surface •Veneras (1970’s) spacecraft landed on the surface •Detected lightning, thunder & returned a few pictures of the surface •Venus Express (2006 - ?) currently orbiting the planet •Discovered huge polar vortexes of unknown origin in the atmosphere Video (5:00) “Atmosphere & Weather on Venus” 5 Notes Unit IV-II “Earth & Mars” Name: _________________ S.W.B.A.T • ______________ physical characteristics of Earth & Mars • Compare & ______________ both planets • Understand why Mars ______________ is important & relevant Earth • ______________ of the terrestrial planets • Only planet where ____________ is known to thrive • Average ______________ from the Sun: 1 AU or 150 million km (about ____ million miles) • Tilted 23.5 degrees from the ______________ (solar) plane • This tilt causes the ______________ • 6300 km (3900 miles) in ______________ • Orbits the _________ in 365.24 days • Spins once on its ___________ every 24 hours (synodic day) • Only inner planet with one ______________ moon • ______________ temperature averages about 52oF (11 oC) • Water covers ____% of the surface • Iron core; liquid molten __________ (thickest layer); thin crust • Atmosphere 77% ______________; 21% oxygen; 2% Argon • ______________ provided mostly by biological processes (photosynthesis) Mars • Average ______________ 1.52 AU from the Sun or 228 million km (142 million miles) • ____th planet from the Sun • 3600 km (2240 miles) in _____________ • ______________ once every 24 hours & 39 minutes • Axial tilt about 25o causing ______________ temperature changes like Earth • _____________ ice caps grow & recede with the seasons (like ______________) • Takes about 2 years to ______________ the Sun • Highly ______________ orbit - .093 eccentricity • Average surface _____________ -67oF (-55 oC) • Temperature ______________ from -270 to +80oF (-168 to + 27 oC) • ______________ includes possible solid core; mantle & crust • Lithosphere is _____________ than Earth’s because Mars (smaller) cooled ______________ • Very weak to non-existent ______________ field • Two small moons – Phobos (“fear”) & Deimos (“terror”) are likely ______________ asteroids • Soil is red due to iron oxide (______________ of rocks) • ______________ ice caps made up of mostly water • If all the _____________ melted Mars would be covered by an average depth of _______ft! • ______________ features prominent • Water once ______________ freely & collected in seas or oceans • Salty water may still “______________” to the surface from crater walls • ______________ canyon – Valles Marineris 4,000 km long • Largest ______________ (inactive) Olympus Mons – 3 times higher than Mt. Everest • Atmosphere is 100 times ______________ than Earth (94% CO2) • Currently very ___________ & very ___________ • Two ground ______________ & three satellites are currently studying Mars • Other ______________ included Mariner 4 (1965) flyby; ViKings 1 & 2 (1976) that landed & tested (inconclusively) for ______________ life • Many more ______________ missions will visit Mars • Future ____________ missions are planned; Europe & India are also _____________ more space probes • Eventually a ______________ mission (U.S. or ?) will occur Why Mars? • Was once a wet, blue-world like ______________ • Still the most _____________ - like planet in our solar system • Life may have ______________ & may still be present 3/23/20 • Identify physical characteristics of Earth & Mars • Compare & contrast both planets • Understand why Mars exploration