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Home , Astronomy, Axial tilt, Venus

Notes Unit IV-I “ & ” Name: ______S.W.B.A.T • Identify ______characteristics of Mercury & Venus • Understand how the two ______planets compare • Discuss the evolutionary ______of both Mercury • Smallest, closest & ______planet to the • Heavily cratered surface resembles the ______• Average ______from the Sun .39 AU or 58 million kilometers (36 million ______) • 2440 km in ______or about .38 the of • ______the Sun in 88 days • Spins ______on its axis every 59 days (sidereal period) • Surface ranges from - 300oF to + 800oF (over ______difference!) • Only inner planet besides ______to have a measurable • Inner core (nucleus) is very ______• Iron core spins ______an electric/magnetic field effect like ______• Caloris Basin – very large ______structure near the created about ____ billion ago • One of the ______impact basins in the • 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 composition • ______axial tilt (3o) • Highly ______orbit (.206 compared to Earth’s .016) • No ______& no (real) • Mercury may have been ______by a early in its 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 = 225 ______days • One ______day = 243 Earth days • A Venusian is longer than its ______! • Rotates opposite or ______from all the other planets (east to ) • Most ______planet – 177.4o from the solar plane • Tilt may be due to a ______later in formation • Internal ______resembles Earth – core, , 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 • 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 • “______” – trapping the Sun’s ______at the surface • Causes to be over _____oF – hotter than Mercury • Almost ______orbit - .008 eccentricity • No • (1989) ______over 160 volcanoes & 1000 craters on the ______• ’s (1970’s) ______on the surface • Detected ______& thunder & returned a few pictures • (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 ) surface that •2440 km in radius or resembles the about .38 (less than half) the size of Earth

• 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 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

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•Ver y dense metallic/rock crust composition •Small (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 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 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 of unknown origin in the atmosphere Video (5:00) “Atmosphere & on Venus”

5 Notes Unit IV-II “Earth & ” 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 (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% ; 2% • ______provided mostly by biological processes () 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 (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 – (“fear”) & (“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) – 3 times higher than Mt. Everest • Atmosphere is 100 times ______than Earth (94%

CO2) • Currently very ______& very ______• Two ground ______& three are currently studying Mars • Other ______included (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 • may have ______& may still be present

3/23/20

• Identify physical characteristics of Earth & Mars • Compare & contrast both planets • Understand why Mars exploration is important & relevant

Astronomy

•Largest of the •Tilted 23.5 degrees terrestrial planets from the •Only planet where life (solar) plane is known to thrive •The tilt of the axis •Average distance from causes the seasons – the Sun: 1 AU or 150 along with Earth’s million km (about 93 revolution around million miles) the Sun

•6300 km (3900 miles) in radius •Orbits the Sun in 365.24 days Video (2:24) “Earth’s Seasons” •Spins once on its axis every 24 hours (synodic day) •Only inner planet with one major moon

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•Surface temperature averages about 52oF (11 oC) •Water covers 71% of the surface •Iron core; liquid molten mantle (thickest layer); thin crust

•Atmosphere 77% ; 21% oxygen; 2% Argon •Oxygen provided mostly by biological processes (photosynthesis)

•Average distance 1.52 AU from the Sun or 228 million km (142 Million miles) •4th planet from the Sun •3600 km in radius •Rotates once every 24 hours & 39 minutes

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•Axial tilt about 25o causing seasonal temperature changes like Earth •Polar ice caps grow & recede with the seasons (like Earth)

•Takes about 2 years to •Interior includes possible solid orbit the Sun core; mantle & crust •Highly elliptical orbit •Lithosphere is thicker than (.093) eccentricity Earth’s because Mars (smaller) cooled faster •Average surface temp. - 67oF (-55 oC) •Temperature ranges from - 270 to + 80oF (- 168 to + 27 oC)

•Ver y weak to non-existent magnetic field •Two small moons – Phobos (“fear”) & Deimos (“terror”) are likely captured

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•Soil is red due to iron oxide (rusting of rocks) •Polar ice caps made up of mostly water •If all the water melted the planet would be covered by an average depth of about 70 feet ROVER OPPORTUNITY EXPLORING MARS SINCE 2005

• features •Largest – prominent Valles Marineris •Water once flowed 4,000 km long freely and collected in •Largest seas or oceans (inactive) Olympus Mons – 3 times •Salty water may still higher than Mt. “bubble” to the surface Everest from crater walls

4 3/23/20

• Atmosphere is 100 • Other missions times thinner than included Mariner 4 Earth (94% CO2) (1965) flyby; Vikings 1 & • Currently very dry & 2 (1976) that landed & very cold tested (inconclusively) • Two ground rovers & FIVE satellites are for microbial life currently studying • Many more robotic Mars missions will visit Mars Video (1:30) “NASA’s MAVEN Reveals How Mars May Have Lost Its Water”

•Future NASA missions are planned; Europe & India are also sending space probes •Eventually a manned mission (U.S. or ?) will occur

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•Was once a wet, blue-world like Earth •Still the most earth-like planet in our solar system •Life may have evolved & may still be present Video (9:33) “Why Mars Died & Earth Lived”

• Using a Venn Diagram – compare & contrast both Earth & Mars. Include facts from your notes & textbook

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