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AST251 MARCH 19.docx


Department
Astronomy & Astrophysics
Course Code
AST251H1
Professor
Susan Pfieffer

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AST251 MARCH 19, 2012
FROM JOVIAN AND EXTRASOLAR
RECAP
- Mars warmer, may have liquid water on mars today
The outer solar system
- Jupiter 62 moons Saturn 60 and Uranus 27 and 13 for neptine
Jovian moons
- Jup, styrn nepturn,
First dis
- By Galileo, looked at Jupiter dots always appeared in line and orbited Jupiter as Jupiter moved
not fixed stars
- Orbital periods few days very quickly
- Heliocentric
- Obkects circle jup not outrageous circle around sun
- Biggest moon staurn was tian by Huygens after the probe
Galiean moons
- Bc gal dicoverd,
- Io eurp, gan and calisto distance closer to far, size of moon,
- 4 moons part of the large jovian moons
- Saturn titan
- And Neptune triton
- Gan big the mercury and Pluto can deform rocks in circle shape and orbit in equatorial plane of
planet
Moons of jovian planets
- Sun in middle, gas disk in middle for planetismals, gaseous outer planets have own disks, centur
jupoiter around form seprearte planetiskmals mini solar systems same rot as big planet
- One exception is trition opp of Neptune and not in equatroal plane it was captured triton like
Pluto happen come to close and captured by it
- Pluto is eccentric orbit further then Neptune but other inside Neptune orbit and may get
captured but captire unlikely
Composition
- Mixture of rocks and ices, cinsitent of solar nebula model, ice to condense further out

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- Jupiter only water ice, temp cold enough to water to form but
- Closest to furtherst fraction of ice increases with furthest, hotter closer Jupiter, io little water
- Staurn beyond more ice and organic mole ices
- Know density and comp send space crafts nearby and compute mass and size and get density
Captured moons
- So small not round
- Saturns moons all shapes and sizes
- Mostly captured asteroids
- Orbits all over the place
- Like asteroid no role discussion in life
Rings
- Asteroid in rings fo planets most famo is Saturn very small particles dust to grains to boulders
- Jovian has rings
- Thines 1km, extremely thin
- Sheet paper 30 meters across
- Structure of them determine by moons that orbit the rings separd moons sheprarrd the rings
Large moons of jup
- Properties
- Density is lower earth bc ice
- Decreases density further from Jupiter bc water ice increases rock decreases
- In nebula condesns further form Jupiter
Orbits of the for main moons
- Each of 4 moons orbit about axis
- Eurpa period is twice of ios io twice europa once,
- Are important for life
Synchrous rotation
- Rotation period like earths moon, once axis per orbit show same side to earth
Tidal forces
- Newton gravity stonger force if two bodies close together and weak further
- Distance earth moon such center of eath accelation of eath in center balance by moon, close
side closer to moon has accleation to moon
- Far side of earth less acc or force moon not pull strong lack of focrce manifest pull in opp
direction

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- Earth Is deformed, and in water, water rises average 2 avg land deforems by land by 1cm app for
any body in solars system
Contd
- Tidal force with roation
- Rotates time bulge to form bulge move ahead of moon off by cetain angle by blue relative black
dash
- Two effects moons gravity acts on bulge slows rot of earth tiny bit longer days 1 sec 50000
years, 1000 sex 50 million, 100000 sec longer then earth, earth rot faster day lasted 6 hrs
- 6hrs to 24 today casue by moon
- Attracts moon moves quicker then actually would increase distance to moon by 4cm by year
laser light by left mirrors on moon
- Ss so old large distance
- Past closer on tenth current distance and 10 times bigger
- Earth slowing down
- Same to moon in past moon faster but slower
- Tidal lockuing very quickly
- Galilean moons born with roation rates but by synchrous rotation
Volcanism on io
- Io has craters all over the place
- Lava flow lava on io hotter on earth
- Exteremly geologically active
- Hotspots on io not good for life bc lava and no life
- Why so hot g
Most important for explain iinteral temps of terrestrial so d and so c and d
Why mars so different from earth bc of the size, lack of magnetic field was lower temp of mars bc no
liquid iron or concetion lower temp by lower size
Ios temp
- Why io hot bc of tidal forces
Tidal heating
- Io not circular, closer and further, ellipse Jupiter is one focal point, distance changes strength
tidal force changes, closer large every 2 days different direction bu sig amount generates lot of
heat 200x then radiaoactive heat then earth
- Origan tides is earths tides now not earths tides at all
Orbital resonance
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