February 11, 2003Lynn Cominsky - Cosmology A3501 Professor Lynn Cominsky Department of Physics and Astronomy Offices: Darwin 329A and NASA EPO (707) 664-2655.
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February 11, 2003Lynn Cominsky - Cosmology A3501 Professor Lynn Cominsky Department of Physics and Astronomy Offices: Darwin 329A and NASA EPO (707) 664-2655 Best way to reach me: firstname.lastname@example.org Astronomy 350 Cosmology
February 11, 2003Lynn Cominsky - Cosmology A3502 GEMS: Invisible Light Sources and Detectors Different stations have different types of light sources and detectors All stations have same set of materials Try each of the 5 stations For each material: Predict whether or not it will block the light, then test your prediction Write your predictions and results down on the worksheets that are provided Hand in worksheets before leaving class
February 11, 2003Lynn Cominsky - Cosmology A3503 SIRTF video Seeing the World with Infrared Eyes Starring Michelle Thaller from JPL Infrared is brighter where things are hotter Also –check out this powers of ten java applet on line - http://micro.magnet.fsu.edu/primer/java/scienceopticsu/powersof10/
February 11, 2003Lynn Cominsky - Cosmology A3504 Looking back through space and time Constellation-X JWST, FIRST MAP, Planck LISA, GLAST Big Bang inflation first stars, galaxies, and black holes clusters and groups of galaxies microwave background matter/radiation decoupling Early Universe Gap First Stars Gap
February 11, 2003Lynn Cominsky - Cosmology A3505 Ultimate Time Machine Doing astronomical observations is like traveling back in time If an galaxy is 1 million light years away, then the light that you are seeing left that galaxy 1 million years ago, and you are seeing what it looked like long ago Do the Time Machine Activity
February 11, 2003Lynn Cominsky - Cosmology A3506 Powers of Ten Earth diameter ~1.3 x 10 4 km
February 11, 2003Lynn Cominsky - Cosmology A3507 Powers of Ten Solar System diameter ~5.9 x 10 9 km
February 11, 2003Lynn Cominsky - Cosmology A3508 Solar System Relative sizes and order of planets Sun Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
February 11, 2003Lynn Cominsky - Cosmology A3509 Planet Distance Orbital Period Diameter Mass Moons (10 3 km) (days) ( km) (kg) Mercury 57910 87.97 4,880 3.30e23 0 Venus 108200 224.70 12,104 4.869e24 0 Earth 149600 365.26 12,756 5.9736e24 1 Mars 227940 686.98 6,794 6.4219e23 2 Jupiter 778330 4332.71 142,984 1.900e27 39 Saturn 1429400 10759.50 120,536 5.68e26 30 Uranus 2870990 30685.00 51,118 8.683e25 21 Neptune 4504300 60190.00 49,532 1.0247e26 8 Pluto 5913520 90800 2274 1.27e22 1 Solar System
February 11, 2003Lynn Cominsky - Cosmology A35010 Formation of the Solar System Activity Examine the figures and tables that are provided in the handout Answer the questions on the worksheet Feel free to discuss them with your neighbor!
February 11, 2003Lynn Cominsky - Cosmology A35011 Solar system architecture The planets are isolated from each other without bunching, and they are placed at orderly intervals The planets' orbits are nearly circular, except for those of Mercury and Pluto. Their orbits are nearly in the same plane; Mercury and Pluto are again exceptions. All the planets and asteroids revolve around the Sun in the same direction that the Sun rotates (from west to east).
February 11, 2003Lynn Cominsky - Cosmology A35012 Solar system architecture Except for Venus, Uranus, and Pluto, the planets also rotate around their axes from west to east. Studies of chemical composition suggest that the small, dense Terrestrial planets are rocky bodies that are poor in hydrogen; the large, low-density Jovian planets are fluidlike bodies that are rich in hydrogen; and most of the outer planets' satellites, comets, and Pluto are icy bodies.
February 11, 2003Lynn Cominsky - Cosmology A35013 Solar system architecture The Terrestrial planets have high mean densities and relatively thin or no atmospheres, rotate slowly, and possess few or no satellites--points that are undoubtedly related to their smallness and closeness to the Sun. The giant planets have low mean densities, relatively thick atmospheres, and many satellites, and they rotate rapidly--all related to their great mass and distance from the Sun.
February 11, 2003Lynn Cominsky - Cosmology A35014 Formation of the solar system Animation shows a simplified model
February 11, 2003Lynn Cominsky - Cosmology A35015 Solar system formation Protoplanetary Nebula hypothesis: Fragment of interstellar cloud separates Central region of this fragment collapses to form solar nebula, with thin disk of solids and thicker disk of gas surrounding it Disk of gas rotates and fragments around dust nuclei– each fragment spins faster as it collapses (to conserve angular momentum) Accretion and collisions build up the mass of the fragments into planetesimals Planetesimals coalesce to form larger bodies
February 11, 2003Lynn Cominsky - Cosmology A35016 Solar System Formation Formation of the Sun Solar nebula central bulge collapsed to form protosun Contraction raised core temperature When temperature reaches 10 6 K, nuclear burning can start Solar winds could have blown away remaining nearby gas and dust, clearing out the inner solar system
February 11, 2003Lynn Cominsky - Cosmology A35017 Formation of Inner Planets While the terrestrial planets formed (and shortly thereafter), they were bombarded by many planetesimals Bombardment made craters and produced heat which melted the surfaces, releasing gases to form atmospheres, and forming layered structures (core, mantle, crust) Additional heat provided by gravitational contraction and radioactivity
February 11, 2003Lynn Cominsky - Cosmology A35018 Cratering Mercury and the Moon show the results of bombardment during early formation of solar system Mercury Moon
February 11, 2003Lynn Cominsky - Cosmology A35019 Earth’s Surface Q: Why does the Earth’s surface show little evidence of cratering? Bombardment of Earth was similar to that of the Moon, Venus, Mars and Mercury A: Earth’s surface is actively reforming due to volcanic activity, erosion from water, plate tectonics,etc.
February 11, 2003Lynn Cominsky - Cosmology A35020 Volcanic Activity Io Jupiter’s Moon) shows volcanic activity Venus also has lava flows Prometheus volcano on Io Magellan Radar image of Venus
February 11, 2003Lynn Cominsky - Cosmology A35021 Erosion and Water Erosion (most likely due to liquid water) also seems to have affected Mars, which also has mountains and craters Moon has frozen water at poles but no signs of erosion Mars
February 11, 2003Lynn Cominsky - Cosmology A35022 Where is the Water? Europa (Jupiter’s Moon) thin outer layer of water ice (1-10 km thick) possible liquid water ocean underneath the surface Callisto (Jupiter’s Moon) Ice-rock mix throughout Possible salt water underneath surface
February 11, 2003Lynn Cominsky - Cosmology A35023 Where is the Water? Saturn Rings are mostly water ice Will be studied by Cassini in 2004 Titan (Saturn’s Moon) Water icebergs in an ocean of methane? No water in atmosphere Huygens probe will be dropped from Cassini
February 11, 2003Lynn Cominsky - Cosmology A35024 Elements in the Planets Chemical composition at formation depended on temperature (mostly determined by distance from Sun) Asteroid belt had lower temperature, so carbon and water-rich minerals could coalesce in the planetesimals From Jupiter outwards, temperatures were much lower, so frozen water coalesced with frozen rocky material, or at even lower temperatures, frozen methane or ammonia
February 11, 2003Lynn Cominsky - Cosmology A35025 Formation of Moon Lunar samples from Apollo revealed the similarity (but some differences) between the materials in the Earth’s crust and mantle and the Moon Collisional ejection would explain these similarities – a Mars sized body impacts the cooling Earth – part is absorbed, part splashes out material which cools to form the Moon Problems remain with the lunar orbital plane vs. the equatorial plane of the Earth
February 11, 2003Lynn Cominsky - Cosmology A35026 Formation of Earth’s Moon Simulation shows formation of Moon due to impact on Earth
February 11, 2003Lynn Cominsky - Cosmology A35027 Formation of Outer Planets In the outer, cooler regions, icy planetesimals collided and adhered. Hydrogen and helium were then accreted onto these Earth-sized bodies. More H and He adhere to larger bodies, explaining their relative lack in Uranus and Neptune Uranus and Neptune are richer in heavier elements such as C, N, O, Si & Fe
February 11, 2003Lynn Cominsky - Cosmology A35028 Formation of Outer Planets Formation of moons of Jupiter and Saturn are mini-versions of the solar system evolution Heat from Jupiter when it formed resulted in inner moons that are rocky, and outer moons that are icy Comets and Kuiper belt objects are remnants of original icy planetesimals, located far from Sun
February 11, 2003Lynn Cominsky - Cosmology A35029 Rings Saturn has 7 named rings (A-F) Jupiter has faint dark rings A-ring B-ring Cassini division Encke division
February 11, 2003Lynn Cominsky - Cosmology A35030 Rings Uranus has 11 known rings HST image of Uranus and its rings Neptune has 3 dark rings HST image of Neptune
February 11, 2003Lynn Cominsky - Cosmology A35031 Formation of Rings Rings appear too young to be primordial – maybe only 10 8 y - i.e., they must have formed after the planets Rings are ubiquitous in the outer planets – whereas we once thought they were rare (only Saturn had rings) Perhaps collisions between moons and interlopers provides material for the rings – seems to work for Uranus and Neptune, but not for Jupiter and Saturn
February 11, 2003Lynn Cominsky - Cosmology A35032 Formation of Rings Saturn’s rings have a resonant relationship with its satellites – i.e., the satellites sweep out gaps between the rings and create fine structure in the patterns seen in the rings A-ring Resonance – the satellite Janus orbits Saturn 6 times while the ring material orbits 7 times, creating a six-lobed structure at the ring’s outer edge Cassini gap – Mimas has a 2:1 resonance with the outer edge of the B-ring at the gap
February 11, 2003Lynn Cominsky - Cosmology A35033 Is Pluto really a planet? Smallest planet, has elliptical, highly inclined orbit Usually furthest from Sun, but orbit crosses inside Neptune Smaller than 7 moons in our solar system But it has its own moon named Charon It resembles asteroids Rock and ice, little atmosphere Pluto and Charon
February 11, 2003Lynn Cominsky - Cosmology A35034 Meteorites Most meteorites are chunks of asteroids, the Moon or Mars; some are from comets >50 billion meteorites have traveled between Earth and Mars since the birth of the solar system Panspermia = Life comes from space Some think meteorites could have carried life from Mars to Earth or vice versa
February 11, 2003Lynn Cominsky - Cosmology A35035 Life on Mars? “Face on Mars” 1976 Viking View Mars Global Surveyor Image April 2001
February 11, 2003Lynn Cominsky - Cosmology A35036 Life on Mars? Martian Meteorite Found in Antarctica in 1984 but origin is Mars Left Mars 16 million years ago, arrived in Antarctica 13,000 years ago Evidence of water infiltration while on Mars Carbonite mineral globules contain shapes that could be dead, fossilized bacteria and their byproducts MeteoriteCarbonate GlobulesFossilized Shapes
February 11, 2003Lynn Cominsky - Cosmology A35037 Planetary Missions MESSENGER (MErcury Surface, Space ENvironment, GEochemistry and Ranging), being built for launch in 2004, arrives at Mercury in 2009 Venus program – no current plans Mars program - Pathfinder (1996), Global Surveyor (1999) then two disasters. Two new Rover missions are in the works – with launches in May 30 and June 25, 2003 Landings on Mars - January 4 & 25, 2004
February 11, 2003Lynn Cominsky - Cosmology A35038 Planetary Missions Galileo mission is orbiting Jupiter, currently sending back data – flew by Io on 1/17/02, and by Amalthea on 11/05/02 --will plunge into Jovian atmosphere in September 2003 Tape recorder failures incurred when Galileo flew close to Jupiter in November during the Amalthea flyby. Data are just now being recovered. Amalthea data may be present on the tape recorder, have not yet been released.
February 11, 2003Lynn Cominsky - Cosmology A35039 Cassini mission to Saturn arrives July 2004. Will drop an ESA probe (Huygens) onto Titan, and flyby Titan and three smaller moons. New Horizons - Pluto –Kuiper belt mission was chosen, and funded through 2002 by NASA. FY03 budget is uncertain. If funded, will launch in 2006, arrive at Pluto by 2015 Europa orbiter still on hold, not in FY03 budget. New propulsion technology is being developed to speed up the journey. Planetary Missions
February 11, 2003Lynn Cominsky - Cosmology A35040 Planets around other stars Over 100 planets around other stars are known
February 11, 2003Lynn Cominsky - Cosmology A35041 Planets around other stars PSR 1257+12 (a radio pulsar, Wolczan 1995) 3 objects orbiting this stellar corpse 1 is the size of the Moon 2 are the size of the Earth probably formed after the supernova explosion that made the pulsar 51 Pegasi (Sun-like star, Mayor and Queloz 1996) at least one object, about 1/2 of Jupiter orbit of only 4 days closer to star than Mercury, so very hot 42 light years from Earth
February 11, 2003Lynn Cominsky - Cosmology A35042 Planets around other stars 70 Virginis (Sun-like star, Marcy and Butler 1996) 116 day orbit 9 Jupiter masses (1 Jupiter = 317 Earth masses) temperature of planet may allow liquid water to exist 78 light years from Earth 47 Ursae Majoris (Marcy and Butler 1996) 1100 day orbit 3 Jupiter masses temperature of planet may allow liquid water to exist 44 light years from Earth
February 11, 2003Lynn Cominsky - Cosmology A35043 Another solar system Upsilon Andromedae: Multiple planet solar system discovered by Marcy et al. a) 4.6 d b) 240 d c) 1313 d Ups And
February 11, 2003Lynn Cominsky - Cosmology A35044 How they find extra-solar planets Stars are too bright to see reflected light from planets directly Unseen planet causes star to wobble as it orbits – star’s light is Doppler shifted
February 11, 2003Lynn Cominsky - Cosmology A35045 Doppler Shift Wavelength is shorter when approaching Stationary waves Wavelength is longer when receding
February 11, 2003Lynn Cominsky - Cosmology A35046 Doppler Shift Comparison of laboratory to blue-shifted object Comparison of laboratory to red-shifted object
February 11, 2003Lynn Cominsky - Cosmology A35047 Doppler Shift Doppler shift song by AstroCapella
February 11, 2003Lynn Cominsky - Cosmology A35048 Other methods: Astrometry – measuring the exact position of a star as it wobbles Hipparcos was an ESA satellite operational from 1989-93
February 11, 2003Lynn Cominsky - Cosmology A35049 Other methods: Photometry – measuring the change in brightness of a star as a planet transits in front of it, obscuring some of the light (~2%)
February 11, 2003Lynn Cominsky - Cosmology A35050 The first transiting planet HD209548 – a visualization by Aurore Simonnet
February 11, 2003Lynn Cominsky - Cosmology A35051 The first transiting planet STARE project found the first transit in HD209548 – Brown and Charbonneau 1999 The planet’s mass is 63% of Jupiter (about 200 Earth masses) with radius 1.3 times Jupiter density 0.39 g/cm 3 (< water!) It transits the star every 3.5 days Its atmosphere is very hot (1100 o C) since it is only 6.4 million km from the star When the planet passed in front of the star, the star’s light passed through the planet’s atmosphere and sodium was observed by HST
February 11, 2003Lynn Cominsky - Cosmology A35052 Saturn mass planets (95 times Earth) Both planets are very close to their stars - This makes them easier to detect If each planet orbited the Earth’s Sun:
February 11, 2003Lynn Cominsky - Cosmology A35053 Latest news (1/6/03) Transiting observation used to discover planet in constellation Sagittarius OGLE TR-56b Most distant and hottest planet yet found – 29 hour “year” for Jupiter-sized planet Transiting planets can be seen to smaller sizes than Doppler Shift technique, offering the possibility that Earth-sized planets can someday be spotted Millions of candidates events were analyzed in the OGLE survey (was looking for gravitationally lensed events) to find 59 possible transiting planets. These were studied using a bigger telescope, and – this one is confirmed, and 2 more may be.
February 11, 2003Lynn Cominsky - Cosmology A35054 Formation of other solar systems Most extra-solar planets that have been discovered have “hot Jupiters” – very close to star compared to our system Most are also found in elliptical orbits vs. circular orbits in our solar system It is hard to explain elliptical orbits in solar systems of any age. Close orbits can be explained by the initial formation of the planet further away, then a migration in towards the star.
February 11, 2003Lynn Cominsky - Cosmology A35055 Disks around stars There is much evidence of disks with gaps (presumably caused by planets) around bright, nearby stars, such as Beta Pic
February 11, 2003Lynn Cominsky - Cosmology A35056 Jupiter’s role in evolution of life Jupiter is believed to have a role in keeping the Earth (relatively) free from bombardment that could end life Nevertheless, there have been at least 6 mass extinctions on the Earth – one bombardment is believed to have killed the dinosaurs – and that wasn’t even the worst one! A theory has been advanced that our quasi-periodic mass extinctions are due to the passage of another planet on a very elliptical orbit “Nemesis” No evidence (other than fossil records) supports the Nemesis theory
February 11, 2003Lynn Cominsky - Cosmology A35057 Mass extinctions Mass extinctions occur every 26-30 million years This one killed the dinosaurs This one killed 95% of all life
February 11, 2003Lynn Cominsky - Cosmology A35058 Solar System habitability factors Temperature range (–15 o C to +115 o C on Earth) Protection (look what happened to the dinosaurs!) Light (or other source of heat or energy) Liquid water (geothermal or atmospheric cycles) Nutrients (chemicals, vitamins, minerals, fertilizers) Energy source (light, food, carbohydrates, fats, sugars)
February 11, 2003Lynn Cominsky - Cosmology A35059 What makes a world habitable? In groups of 3-4, take a set of cards that summarize the properties of various solar system bodies Temperature Water Atmosphere Energy Nutrients Consider the following: What does life need? What kinds of conditions might limit life? Select your top three candidates for life
February 11, 2003Lynn Cominsky - Cosmology A35060 Web Resources Nine Planets tour http://www.seds.org/nineplanets/ninepl anets Mercury MESSENGER mission: http://sd- www.jhuapl.edu/MESSENGER/ Mars Exploration program http://mpfwww.jpl.nasa.gov/ http://mpfwww.jpl.nasa.gov/ Galileo mission http://galileo.jpl.nasa.gov/
February 11, 2003Lynn Cominsky - Cosmology A35061 Web Resources New Horizons Pluto mission http://pluto.jhuapl.edu/mission.htm http://pluto.jhuapl.edu/mission.htm Europa orbiter http://www.jpl.nasa.gov/europaorbiter/EO_Info.htm http://www.jpl.nasa.gov/europaorbiter/EO_Info.htm Transiting planet OGLE-TR-56b http://cfa-www.harvard.edu/press/pr0301.html http://cfa-www.harvard.edu/press/pr0301.html Mass extinctions http://www.bbc.co.uk/education/darwin/exfiles/quest1.htm http://www.bbc.co.uk/education/darwin/exfiles/quest1.htm Solar System Formation activity http://www.astro.washington.edu/labs/clearinghouse/labs/For mss/lab.html
February 11, 2003Lynn Cominsky - Cosmology A35062 Web Resources Extra-solar planet searches http://exoplanets.org STARE: http://www.hao.ucar.edu/public/research/stare/stare.h tml http://www.hao.ucar.edu/public/research/stare/stare.h tml Solar System architecture http://www.physics.gmu.edu/classinfo/astr103 /CourseNotes/ECText/ch11_txt.htm#11.1. http://www.physics.gmu.edu/classinfo/astr103 /CourseNotes/ECText/ch11_txt.htm#11.1. Hipparcos Space Astrometry Mission http://astro.estec.esa.nl/Hipparcos/ http://astro.estec.esa.nl/Hipparcos/