Discover the Universe Week 9
Discover the Universe Week 9 AST 1002
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This 9 page Class Notes was uploaded by Jocelyn on Sunday October 25, 2015. The Class Notes belongs to AST 1002 at University of Florida taught by Reyes, Francisco J in Summer 2015. Since its upload, it has received 28 views. For similar materials see Discover the Universe in Science at University of Florida.
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Date Created: 10/25/15
Tuesday October 20 2015 Discover the Universe Week 9 Chapter 8 Satellites rings and Plutoids Jovian Planets Satellites There are six large satellites similar in size to our Moon 12 medium sized 4001500 km and many small satellites Jupiter 67 Satellites Saturn 62 Satellites Uranus 27 Satellites and Neptune 13 Satellites Jupiter s Satellites lo active volcanoes Europa covered with layer of frozen water strong indications of ocean Ganymede and Castillo may have sub surface ocean Ganymede All of these satellites have sufficient mass selfgravity forcing them to be spherical and most have substantial amounts of ice Largest Satellites 1 QPONFDQT P N Ganymede Titan Mercury Castillo lo Moon Europa Triton Pluto 10Titania Tuesday October 20 2015 lo s Volcanoes 80 active volcanoes have been found using data mainly from Voyager and Galileo spacecrafts Eruptions mainly composed of sulfur and sulfur dioxide What causes lo volcanic activities lo is squished and stretched as it orbits Jupiter This releases heat and rises the internal temperature Elliptical Orbit orbital resonance between the orbital period of lo Europa and Ganymede The three closest satellites line up every 7 Earth days resonance Tugging in the same direction distorts the orbit from a circle to an ellipse Smooth Europa lcy surface covering a large rocky core smooth and young surface Fractured into ice rafts and floes a few kilometers across Repaved by water or geysers through the cracks in the ice Just a few impact crater young surface Salty water oceans below thick layer of ice twice as much water as Earth Mostly salty water some magnesium sulfate Tidal stresses crack Europa s surface ice Similar to icebergs large chunks of ice have been broken and reassembled One possibility 100200 km of convective ice above a rocky core The most probable scenario based on measurement of Europa s magnetic field Thin ice crust a few km thick over a 100 km deep water ocean How can Europa maintain liquid water Tidal heating due to the elliptical orbit Tuesday October 20 2015 Thermal vents may bring the heat from the core Heat may keep the interior temperature above freezing point Possibility of life The existence of water does not imply the existence of life because the salty water is a hostile environment Titan Saturn s largest satellite and the second largest in the solar system Titan is the only satellite in the solar system to have a permanent atmosphere It has a methaneammonia atmosphere The atmosphere is so thick that the surface cannot be seen in the visual part of the spectrum Properties Mass 002 x Earth s mass Radius 04 X Radius of Earth Density 1900 kgmquot3 lcy mantle over a rocky core Composition 80 Nitrogen 3 Methane Argon Hydrocarbons Ethane C2H6 Acetylene C2H2 Ethylene C2H6 Propane C3H8 lo active volcanoes Europa covered with layer of frozen water strong indications of ocean Tuesday October 20 2015 The Huygens Probe The Huygens lander was carried by the Cassini spacecraft Titan s Liquid Lakes Titan s Interior to Exterior Silicate core High pressure ice Liquid water Near surface ice Surface It has a retrograde orbit lt orbits in direction opposite to Neptune s rotation Probably a captured object from the Kuiper belt such as Pluto Voyager 2 detected geysers of nitrogen has rising several km high The gas jets of nitrogen come from liquid nitrogen heated by some internal source of heat 37 K temp and a very thin atmosphere Rings Although all Jovian planets have rings the most spectacular are Saturn s rings They are just a few km thin Rings are not solid objects They are comprised of many small solid particles that in orbit around the planet The primary consultant is water ice Why do rings form The tidal forces of the large planet break apart a close enough moon or satellite Particles that make up that rings follow Kepler s Laws Inner particles revolve faster than those farther out Tuesday October 20 2015 rings are not rotating as a solid body rather individual mooniest are revolving around the planet If ring particles are widely spaced they move independently If the particles are close to each other there is a gravitational interaction between them The gravitational attraction resonance of the satellites or moons clear gaps in rings Saturn and its main rings The Cassini division is caused by a resonance with the orbital period of Mimas one of Saturn s satellites Origin of rings Breakup of shattered satellite Remains of particles that were unable to come together and form satellite The Roche Limit Roche Limit the closest distance an object can come to another large mass object without being pulled apart by tidal forces If the density of the planet is similar to the density of the satellite the roche limit 2446 Rpanet A large moon orbiting inside the Roche limit will be destroyed Roche limits for some planets Earth 18470 km Jupiter 175000 km Saturn 147000 km Uranus 62000 km For comparison Saturn s outer diameter of a ring is 137000 It is inside the Roche limit Comparing Jovian Ring Systems Tuesday October 20 2015 Compared to Saturn the ring system of other Jovian planets have fewer particles are smaller in extent have darker particles The rings of Uranus were discovered in 1977 when the planet passed in front of a star and the rings dimmed the light from the star Pluto a dwarf planet and Charon Discovered in 1930 by Clyde Tombaugh at Lowell Observatory Charon the first satellite discovered was found in 1978 Image taken with ground based telescope Pluto has a total of 5 satellites including Charon Pluto is located at 40 times the Earth s distance from the Sun 40 AU The New Horizons missions launched in January 2006 arrived in July 14 2015 Similar in mass and size to Neptune s large moon Triton Probably formed in the Kuiper belt comet birth place The Kuiper belt is located outside the orbit of Neptune at distances between 3050 AU Pluto has a highly inclined orbital plane Orbital period 248 years Average density 2000 kgmquot3 Pluto has only 20 the mass of our Moon Mass about 00022 mass of Earth Diameter 1160 km 018 diameter of Earth In 2003 it was renamed as a dwarf planet by the International Astronomical Union IAU The New Horizons mission arrived at Pluto on July 14 2015 and it took about 10 yeas to make the trip and also happened to be the first spacecraft to reach Pluto Tuesday October 20 2015 Pluto has haze and blue layers The Kuiper Belt Located outside the body of Neptune A region of the solar system located between 3050 Au from the Sun Bodies from the Kuiper belt are composed of ices mainly methane ammonia and water ices Pluto Eris Makemake and Haumea are examples of Kuiper belt objects Some short period comet periods lt 200 years are also objects that belong to the Kuiper belt The discovery of Eris in 2005 showed that Pluto was no unique These objects seem to be the largest of the Kuiper belt objects known as plutoids The Structure of the Solar System Comets Astronomer Fred Whipple named them dirty snowballs they are composed of dust and rock in methane ammonia and water ices The light we received from a comet is reflected light from the Sun or comes from the gas released by the comet being ionized and excited by UV emission from the Sun and emitting light Parts of a comet Nucleus coma hydrogen envelope and the ion and dust tails The nucleus is the soil part of the comet The size of the nucleus is just a few km in diameter The orbits of most comets take up to 1 million years to orbit the Sun and these comets originate in the Oort cloud Tuesday October 20 2015 The orientation of their orbits are random respect to the plane of the ecliptic Short period comets orbit the Sun in 200 years or less Halley s comet The orientation of their orbits are close to the ecliptic plane Short period comets may have originated in the Kuiper belt Kuiper belt comets get kicked into an eccentric orbit bringing them into the inner part of the solar system The development of the gas and dust tails as the comet approaches the Sun The dust forms when the dust tail which points in the direction of the trajectory of the comet The gas points in direction opposite to the Sun and forms the gas or iron tail Meteoroid Meteor and Meteorite Meteroroid interplanetary rocky material smaller than 100 m down to grain size Meteor When it enters and burns in the Earth s atmosphere Meteorite If some material survives the entry and makes it to the ground Meteor showers are the result of Earth passin through the orbit of a comet which has left debris along its path They take the name of the constellation where the radiant seems to be located Types of Meteorites Stony most common usually covered by a dark crust created by melting of the surface dining the entry in the atmosphere IronNickel easy to find This kind is a fragment of a larger body The body was large enough to generate internal heat and went through the differentiation process StonyIron Most meteoroids are rocky A small fraction are mainly iron and nickel and some contain carbonaceous material rich in organic material Tuesday October 20 2015 Meteoroids are old 45 billion years based on carbon datingmost were formed when the solar system formed Asteroids rocks with sizes greater than 100m across About 2000 asteroids have orbits that cross Earth s path Called NEO Near Earth Objects Most asteroids are in orbit around the Sun in what it is called the Asteroid Belt between the orbits of Mars and Jupiter Some of these may come at distances lt 005 AU from the Earth They are called PHA s Potentially Hazardous Asteroids Extinction of the Dinosaurs A 1015 km size asteroid that collided about 65 million years ago in Chicxulub in the Yucatan peninsula mexico It left a crater about 180 Km in diameter A layer of clay enriched in iridium found in many parts of the world fits the age of the impact lridium is found in meteorites and asteroids The cloud of dust may have shrouded the planet for a few years extinguishing the Sun s rays killing plants and disrupting the food chain The Tunguska event in 1908 in Siberia is one of the most recent The body 30m exploded several km above the surface It did not create a crater just a depression The most recent the Chelyabinsk meteor fell in Russia on February 15 2013 Size was about 1720 m