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Earth Sciences
Earth Sciences 1086F/G
Natalie J.Allen

Eartschi final exam notes Earth Science Final Exam Study Notes Unit 5: The Gas Giant Planets Introduction- Definition of a gas/ice giant:  Large in size and mass  Low density  Composed primarily of hydrogen, helium, methane and ammonia in either gaseous or liquid state Origin in the solar system  Either formed within the first 10 million years of development of star-planet systems, or they didn’t ever develop (because all liquid and volatile elements would gather quickly not slowly like other elements)  The volatile elements grew into large masses very quickly and interfered with orbits of smaller masses, flinging the smaller masses out of the solar system or in towards the center  This period caused adjustments in planetary orbits (planets tossed smaller masses back and forth and some were even hit by the smaller masses) Collision of Shoemaker-Levy 9 with Jupiter  Comet Shoemaker-Levy 9 was captured into orbit around Jupiter sometime in the past  1992: came close to planet and was pulled into 21 pieces  July 1994: As a strand of small comets, the pieces fell back and hit Jupiter  The impacts released energy equivalent to a few million megatons of TNT (A LOT!!) and fireballs were produced that could be seen from Earth  Importance? A) Astronomers could use the impacts to further their understanding of Jupiter’s atmosphere, and they created a relatively good representational model B) Reminds us that planets are hit by large objects very often-including large impacts on Earth (comet that killed off dinosaurs etc.) Chapter 14- Jupiter General planetary properties  Distance from Sun: 5.3 AU  Density: 1.326 g/cc  Rotation: Fast! 9.925 hours, 13.07 km/s  Oblate due to high speeds of rotation  Inclination: Upright! 3 degrees of obliquity  Satellites and Rings: -Approximately 63 satellites orbit the planet -1979: Voyager 1 spacecraft photographed Jupiter’s rings -Very dull, less than 100 times as bright as Saturn’s rings -Insubstantial rings, composed of dust particles Missions  No race for exploration of Jupiter-No landings possible as there is no solid surface to land on!  Important automated missions include: Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Galileo, New Horizons  P1 and P2 have now left the solar system and are no longer in orbit around Jupiter  V1 found active volcanoes, V2 found many of them were erupting  Galileo: Meant to orbit Jupiter for 2 years, lasted through 8 years of collecting data. It was deliberately destroyed because it would have contaminated other experiments -G allowed scientists to hypothesize that Europe (satellite) has a salt-water ocean and may contain microbial life -G was the first probe to fly past an asteroid -G changed the way we think of the solar system  New Horizons: Launched in 2006 -Heading for Pluto, but has passed Saturn and Jupiter and will pass Uranus -Amazing photographs of these planets (Jupiter’s rings, satellites etc.) Geology  Knowledge of rocky core comes from heat flow, density calculation -Where does this heat come from? The slow escape of gravitational energy released during its formation -As the planet took shape, some of its gravitational energy was converted into heat in the interior and this heat is slowly leaking out through atmosphere of planet  Magnetosphere -Jupiter has an extremely strong magnetic field (strongest in solar system except for Sun, 14 times stronger than Earth’s) -It traps electrically charged particles (from solar wind) and turns them into radiation -Auroras like those on Earth occur on Jupiter -Dynamo effect: Atmosphere -Extremely strong winds, think atmosphere -Much heat escaping from interior pf planet -Dry, no condensation Dark Belts and Bright Zones:  Come from the high rate of rotation of the planet  Zones: white or yellow, lower temperature than belts, higher in atmosphere, they are regions of rising gas, brightly lit hence light colour  Belts: reddish brown in colour, higher temperature than zones, lower in atmosphere, they are regions of descending gas, dimly lit hence colour  They are separated by winds blowing at hundreds of km/h Cyclonic Storms  Light and dark spots that are mixed within the belt-zone circulation  Dark spots=openings through which we see deeper, darker clouds  White spots=higher cloud circulations  Great Red Spot: largest white spot, existed for more than 330 years -Twice the diameter of Earth, higher than its surroundings -Formed by rising gas carrying heat upward from deep below the clouds Weather  Weather patterns are dominated by the interior  High speed wings that bound the belts and zones extend deep into the atmosphere  Heat rising from the interior drives convection and generates circulating storms Satellites Regular Satellites: Galilean satellites Properties-  Large and round in size and shape  Stable, simple, circular orbit  Tidally locked to Jupiter  Move in plane equal to planet’s equatorial plane  Formed: a) Out of same nebula that built solar system b) Out of collision (like Moon) Callisto-  If it has layer of liquid water beneath the icy surface, the heat to keep the water from freezing comes from radioactive decay heat from its interior Ganymede-  Largest of Jupiter’s satellites, composed of silicate rock and water ice, and has a molten iron-rich core  Appears to have a liquid water salty ocean, a magnetic field and its own atmosphere Europa-  Mostly made of rock and metal, surface is icy with limited craters, surface has been resurfaced periodically, doesn’t have its own magnetic field Io-  Closest satellite to Jupiter, highest density of all 4 G sats  Has a core of iron (and maybe sulfur), a mantle similar to Earth (silicate minerals), brittle outer crust  No impact craters, meaning the satellite is extremely volcanically active (most in solar system) Potential life?  Slight possibility of bacteria-like life on Europa  Like on Earth, water is needed for life forms to grow, but photosynthesis can’t happen Irregular Satellites=Are of unknown origin or capture, and orbit at great distances and on odd trajectories. Sometimes their orbits are retrograde (opposite to planet’s direction of spin) Trojan Satellites=Orbit Sun but are also gravitationally bound to Jupiter, also considered companions to Jupiter because they don’t actually orbit Jupiter Chapter 15- Saturn General Planetary Properties  Distance from Sun: 9.5 AU  Density: Very low! 0.687 g/cc (Would float on water)  Rotation period: Fast but slower than Jupiter’s, 10.5 hours, 9.87 km/s  Tilt: 26.73 degrees, can been seen from Earth (because of rings)  Has as least 60 satellites and hundreds of rings organized into 8-10 groups Missions  Important missions: Pioneer 11, Voyager 2 and Voyager 2  Cassini-Huygens: First spacecraft to orbit Saturn, launched in 1997 -Entered Saturn’s orbit in 2004  New Horizons: The new information given by NH is still being processed Atmosphere Lack of distinction between atmosphere and planet surface  Slow gradual change from gaseous atmosphere to liquid planet  No surface in the same sense that Earth has, would be impossible to land on Saturn Composition  91% hydrogen, 6% helium, rest is made up of nitrogen, oxygen, carbon, water, ammonia and methane  Outer layers contain hydrocarbons (acetylene, thane, propane, methane) Belt/Zone Patterns  Come about in the same way as Jupiter’s, same compositions (Zones are higher clouds formed by rising gas and belts are lower clouds formed by sinking gas)  Clouds aren’t as distinct as on Jupiter, or as warm Winds  Has fewer winds that bound the belts and zones like Jupiter has, but are stronger Geology  Knowledge of rocky core through high heat flow -Despite low density, Saturn must have a very hot rocky core, as heat flow is high as seen through infrared observations -Helium in liquid hydrogen is falling toward Saturn and the friction of the droplets and the compaction of them in the core heat the planet  Magnetic Field -Matching magnetic and geographic rotational poles=perfectly symmetrical magnetic field -Dynamo through interaction between the core and the metallic hydrogen inner mantle, resulting in a weaker field than Jupiter Rings  Who discovered them? -Christian Huygens  Why do they ‘hug’ the equatorial plane? -Saturn has significant bulge at its equator (due to its fast rotation and its low density), and a body orbiting around Saturn feels a greater pull toward the equator than the polar zones because there is more material below it  What are they made of? -Billions of particles of water ice, mixed in some areas with dirt  Origins? Theory A: Rings were created when Saturn was accreted from nebula Theory B: Rings were created in the last 100,000 years, are young! They were once a satellite of Saturn whose orbit decayed until it came close enough to be ripped apart by the tidal force of interaction with Saturn  Role of shepherd satellites: =Were previously though to act as ring stabilizers, but can actually provide material for rings or take material away -Sometimes, the satellites disintegrate and replenish the ring material, and sometimes the ring material accretes into small satellites -If true, newness of rings cannot be important property used to tell age Satellites  Saturn has at least 60, they look like dirty ice balls  Saturn has one really large satellite, 7 medium sized ones and many tiny ones  Mimas (Image of Death Star-Star Wars) and Iapetus (Line down equator) Titan:  Very large (larger than Mercury, almost as large as Jupiter’s largest satellite)  Has a dense atmosphere with main component nitrogen  Orange coloured atmosphere-due to complex hydrocarbons (methane) that make the surface indistinguishable  Surface is very cold, and there is thus not much biological activity possible (how is there methane then?)  Appears to have continents, ‘oceans,’ sand dunes, volcanoes>Resembles of Earth Enceladus:  Discovered in 1789  Is small, orbits very close to Saturn very fast  Exhibits craters and evidence or resurfacing  Source of material for E-ring  Exhibits great plumes of icy water and snow from fountains along troughs at south pole  Very cold throughout, warmer at south pole (heat comes from friction from tidal attraction of Saturn) Chapter 16- Uranus and Neptune General planetary properties Uranus Distance from Sun: 19.2 AU Density: 1.27 g/cc Rotational period: 17 hours and 14 mins Axial tilt: 98 degrees (almost exactly sideways-was most likely pushed by a large object during heavy bombardment) Orbital period: 84.32 years (very long-increase as you go outwards from Sun) Satellites: 27 Rings: 13 dark, faint individuals Magnetic field: Generated from a spot about 1/3 of the way toward the South Pole. Generator has to do with rotational motion between the ammonia and water ocean layers of the planet. Neptune Distance from Sun: 30.1 AU Density: 1.64 g/cc Rotational period: 16 hours and 6 mins Axial tilt: 30 degrees Orbital period: 164.79 years (an even greater increase) Satellites: 13 Rings: Maybe 5, though 3 distinct Magnetic field: Not very strong, is 55 percent the way to the surface of the planet, and is probably generated by the dynamo effect acting in the conducting fluid mantle. Missions  Voyager 2 is the only mission close enough to Uranus and Neptune to collect reasonable data  New Horizons will cross the orbits of both planets but will be too far from them to collect more than just pictures  The Hubble Space Telescope has also collected much of the information about these planet Atmosphere (Similar for both planets)  Upper atmosphere: Molecular hydrogen and less helium, bit of methane  Next layer down: Increased methane  Farther down: Ammonia and water become significant -Methane causes greenish/bluish tint of planets (methane absorbs the red wavelengths and allows for more blue wavelengths to get through)  No actual surface but upper stratosphere and lower troposphere-temperature rises from top to bottom of troposphere  Belt/zone cloud pattern is controlled by rotation not amounts of sunlight (like Jupiter)  Neptune: Cyclonic storms are very common -Great Dark Spot is close to the equator, and is an anti-cyclone storm -Scooter, Small Dark Spot also exist in the Southern hemisphere Rings and Satellites  Rings are smaller and darker than those of Saturn  Uranus has a bright blue ring, Neptune rings vary in density  Heating of satellites: Due to the distance of Uranus from Sun, they are heated by the radiation belt -Radiation may convert methane trapped in their ices into dark carbon deposits and further darken their surfaces -Radiation comes from core of Uranus -Near the heat source radiation is effective and further away the photons are simply absorbed or scattered, thus defining an outer limit of the ‘belt’  Ice content: Uranus-all satellites contain frozen water and their surfaces are very dark, so astronomers first assumed they were made of dirty ices. Actually, density is too high for just ice, so they are probably a mix of relatively large rock cores surrounded by icy mantles -Water ice is as hard as granite and liquid nitrogen act like water, forming a subsurface layer analogous to the water table beneath Earth’s surface  Triton: Discovered in 1846, has a nearly circular and backwards orbit. Triton is that only large satellite in the solar system with a retrograde orbit. This lowers Triton’s orbit towards Neptune. In the future, it will either break up or crash.  Nerid: Discovered in 1949, orbits in the right direction but has a highly elliptical and very large orbit. Its orbit resembles that of a comet. Unit 6: Plutoids, TNOs and Comets Chapter 17- Plutoids and TNOs Plutoids  Definition: A plutoid is a celestial object that satisfies three conditions: it orbits Sun at an average distance greater than that of Neptune; it is massive enough that its own gravity brings it to hydrostatic equilibrium, making it near-spherical; and it has not cleared the neighbourhood around its path from other orbiting debris  This describes Pluto-like trans-neptunian dwarf planets  Includes Pluto, Eris, Makemake and Haumea Discovery of Pluto  Percival Lowell worked from the observed irregularities in the motion of Neptune, used mathematical calculations like the ones used to find Neptune  Lowell predicted the size and position of Pluto in the sky, and predicted it would be 7 times as large as Earth  Clyde Tombaugh was the one that actually discovered Pluto  Technique: Tombaugh obtained 2 glass plates exposed two to three days apart, and mounted them in a blink comparator (machine with microscope at small spot on one plate and then at the flip of a lever, see the same spot on the other plate) to search them. As he blinked back and forth (with machine), he finally saw an image that had moved from plate to plate (signaling an orbiting planet)  Actual size of Pluto was much smaller than what was expected (and thus had no measurable effect upon the motions of giants such as Uranus and Neptune) Planetary Facts  Orbit: Most planetary orbits in our Solar System are nearly circular, but Pluto’s is elliptical (oval)  Density: 2. 03 g/cc  Tilt: 119.6 degrees, has potential of seasons (not much heat)  Best guess of interior: (outside to inside) frozen nitrogen, water ice, silicate rock and water ice-definitely has a component of rock due to high density Charon  Initially called Pluto’s natural satellite, half the diameter of Pluto  Orbits Pluto in a nearly circular orbit around Pluto’s equator  They are tidally locked to each other  The balance point of gravity is not within Pluto but is between the two planets  Charon is thus not actually a satellite of Pluto, but a binary planet  They together contain 35% ice and 65% rock Eris, Makemake, Haumea-Trans-Neptunian Objects  Eris: Largest TNO found so far -Orbits Sun in a region of space farther than Pluto but very slightly closer to Sun
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