ASTR Final Exam Study

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ASTR Final Exam Study
2015-05-11 16:17:21
ASTR 206 Final

Final Exam Study
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  1. Formation of Jovian Planets
    • -Core Accretion Model (Bottom-Up): Started with a core of icy and rocky materials. Gravitational pull allowed it to trap H and He
    • -Disk Instability Model (Top-Down): Protoplanetary disk-like formation. Started with a clump of H and He
  2. Jupiter Overview
    • -2.5 times size of all planets in solar system combined
    • -4th Brightest object in sky
    • -Fastest spinning planet in solar system (10 hour days)
    • -Period: 11.9 years
    • -Eccentricity: 0.05
    • -Semimajor axis: 5.2 AU
    • -Oblate (flatter at poles due to high rotation speed)
    • -Mass: 317 Earth masses
    • -11.2 Earth diameters
  3. Jupiter Exploration
    • Chronological Order
    • -Pioneer (mid 70's)
    • -Voyagers 1 and 2 (79')
    • -Galileo (95')
    • -Cassini (2000)
    • -New Horizons (Jupiter fly-by in 07')
    • -JUNO (On way to Jupiter)
  4. Jupiter Facts
    • -Struck by comet Shoemaker-Levey in 1994
    • -Comprised of 75% H, 24% He, and 1% other.
    • -Radiates 1.6 times the amount of energy it gets from the sun. Residual heat from collapse of solar nebula. Also slow thermal contraction
    • -Internal heat drives atmospheric weather
  5. Jupiter's Atmosphere
    • -Tops of clouds visible, made of H and He with some methane, water vapor, and ammonia.
    • -Rapid rotation creates visible bands, which blow in opposite directions.
    •   -Belts are the dark zones and are lower in the atmosphere
    •   -Zones are the light zones and are higher in the atmosphere
    • -Equator rotates faster than the poles do
  6. Jupiter's Red Spot
    • -A storm that has lasted over 400 years
    • -Dark IR, so cooler and higher in atmosphere
    • -Since it is brown but high in atmosphere, it is similar to belts and zones
    • -Other storms: brown ovals are holes in upper cloud systems and white ovals are large storms but smaller and also high in atmosphere
  7. Jupiter's Interior
    • -Rocky core larger than Earth
    • -Core may be surrounded by liquid water, ammonia, methane, and other.
    • -Middle layer is helium and liquid metallic hydrogen. (Under extreme pressure, like in inner Jupiter, H can become metallic and conduct electricity)
    • -Outer layer is H and He
  8. Jupiter's Magnet
    • -Thought to be because of liquid metallic hydrogen.
    • -14 times stronger than Earth's
    • -Largest magnetosphere in solar system
    • -Jupiter's rotation rate determined by magnetic field, which is static, so it is a great indicator of rotation.
  9. Jupiter's Other Features
    • -Large and bright
    • -Partially caused by Io
    • -Jupiter has rings made of ice and discovered by Voyager. Not visible from Earth
  10. Saturn Basic Facts
    • -9.5 AU
    • -29.5 year period
    • -Eccentricity: 0.05
    • -Day: 10.2 hours, only slightly longer than Jupiter
    • -40 Moons
    • -9.5 Earth diameters
    • -More oblate than Jupiter
    • -Lowest density of all planets
    • -27 degree tilt
  11. Saturn Missions
    • -Flybys by Pioneer Saturn and Voyagers 1 & 2
    • -Orbiters/Landers: Cassini and Huygens
  12. Saturn's Rings
    • -Galileo thought they were ears that "disappeared." He died not finding the answer
    • -Largest rings by 10^5
    • -Composed of ices
    • -May be youngest rings
    • -Gaps in the rings
    • -Particles in rings can be micrometers to 10 meters in size
    • -3 Broad rings
    • -10 km thick
    • -To remain intact, ring particle orbits must be highly circular and on a plane
  13. Saturn's Atmosphere
    • -Mostly H with small amounts of He and Methane
    • -Also has atmospheric banding like Jupiter
    • -Sometimes there are visible storms but they are short lived
    • -Wind speeds on Saturn are faster than on Jupiter
    • -North pole region has hexagonal shape
    • -South pole has giant storm with an eye unlike any seen on Earth
  14. Saturn's Internal Heat Source
    • -Stronger heat source than Jupiter
    • -Cool atmosphere causes He to rain down, causing an He deficiency near upper atmosphere and this causes an H2 friction that causes the planet to heat
  15. Saturn's magnetic Field
    • -Weaker than Jupiter's due to less liquid metallic hydrogen
    • -Large magnetosphere, but not detectable from Earth
    • -Saturn's magnetic field and axis are in complete uniform line
  16. Planetary Rings
    • -All jovian planets have rings
    • -No terrestrial planets have rings, but all terrestrial planets likely did at one point
    • -Ring gaps can be caused my Shepard satellite objects or by ring particles in resonance with the planet or a satellite
    • -Ring color depends on light refracting from differently sized ring particles
    • -Particles do not migrate outside their orbit
    • -Rings are likely short-lived because gravity from the planet, satellites, and the sun disturb rings as do collisions
  17. The Roche Limit
    -Due to tidal forces, all planets have a roche limit. within the roche limit, satellites break apart. Outside of it, they remain intact. All rings occur within a planet's roche limit.
  18. Galilean Satellites (Jupiter's Satellites)
    • Closest to Furthest
    • -Io (2nd smallest, Very volcanic b/c tidal forces from Jupiter)
    • -Europa (Smallest, icy and may have under-ice ocean)
    • -Ganymede (Largest, moon colored)
    • -Castillo (2nd Largest, dark)

    • -They all make shadows on Jupiter and can be seen through small telescopes 
    • -Obey Kepler's laws
    • -Io, Europa, Ganemede are in 1:2:4 orbital periods
  19. Galilean Satellite Formation
    -May have formed by mini-protoplanetary disk. Supporting evidence comes from the fact that density decreases as distance from Jupiter increases
  20. Io
    • -Innermost Galilean satellite
    • -Pizza color/pattern
    • -1.7 day period
    • -Most geological active in solar system
    • -Youngest sufrace in solar system: no impact craters
    • -So active that it has a new surface every 100 years
    • -Active surface is due to intense tidal flexing from Jupiter
    • -In one orbit, parts of Io's surface can raise as much as 300 ft, causing tremendous friction
    • -Io leaves a plume in a ring shape around Jupiter as it travels caused by its volcanos
  21. Europa
    • -Smallest Galilean satellite
    • -Period: 3.5 days
    • -One of the brightest solar system objects b/c of ice
    • -No elevation changes more than 1km. Very smooth
    • -Few craters
    • -Ice from water according to spectroscopy
    • -Surface criss-crossed by fractures in ice, thought to be caused by the tides of a liquid ocean underneath
    • -Inner layer of salt water predicted to be cause of the magnetic field
  22. Ganymede
    • -Largest Galilean satellite/satellite in solar system
    • -Period: 7.1 days
    • -Tidally locked with Jupiter like Earth's moon
    • -Low mass because of a composition of equal parts ice and rock
    • -Dark areas more heavily cratered than light areas
    • -Younger light areas that are heavily grooved
    • -Older dark areas with many craters

    -Ganymede only moon to have a magnetosphere. Internal heat from formation or electromagnetic heating from Jupiter. Active interior
  23. Castillo
    • -Second largest Galilean satellite
    • -Period:16.7 days
    • -Low density
    • -Tidal locking with Jupiter
    • -Not part of the 1:2:4 orbital resonance as other Galilean satellites
    • -Most heavily cratered body in solar system b/c it is also the oldest surface in solar system
    • -Geologically dead
    • -May have salt water ocean under surface
    • -Darkest Galilean satellite
    • -No craters on it deeper than 1km
  24. Titan
    • -Titan: 2nd largest satellite in solar system, but smaller than Ganymede.
    • -Thick atmosphere and higher atmospheric pressure than on earth
    • -Synchronous rotation with Saturn
    • -Atmosphere rich in methane, nitrogen and hydrocarbons
    • -Titan's surface not visible from space b/c thick atmosphere
    • -Young surface, may have cryo-volcanos
    • -Evidence of lakes made of liquid methane
  25. Saturn's Other Moons
    • Closest to Furthest. All moons are tidally locked with Saturn. All are low density and primarily ice
    • -Mimas: Death-star looking b/c large crater
    • -Enceladus: highest albedo in solar system. May have liquid water beneath ice surface. May have tidal heating from other Saturn satellites keeping interior warm. Has geyser-like sprays
    • -Tethys
    • -Dione
    • -Rhea
    • -Lapetus: Has oddly shaped rige on dark side
  26. Uranus and Neptune
    • -Uranus visible with naked eye, Neptune not
    • -No surface features visible without filters
    • -More heavy elements than Saturn/Jupiter
    • -Likely formed elsewhere and migrated to current orbits
    • -Have magnetic fields due to ionized water, do not have liquid interiors
    • -Magnetic fields steeply inclined relative to axis of rotation and also offset from the center of the planet
    • -Both have thin, dark rings
  27. Uranus Facts
    • -14 times Earth mass
    • -Orbital period: 84 years
    • -19 AU from sun
    • -17 hour days
    • -27 moons
    • -Mostly made of H, He and Methane too
    • -No internal heat source
    • -Tilt of 92 degrees. Thought to be b/c of a collision
    • -Clouds running up and down b/c tilt
  28. Neptune Facts
    • -17 times Earth mass
    • -Orbital period is 165 years
    • -29.8 AU from sun
    • -16 hour days
    • -13 moons
    • -Atmosphere is also H, He, and methane
    • -Has internal heat source
    • -Fast rotating clouds and storm systems
    • -Clouds made of frozen methane
    • -More activity than Uranus b/c active interior
  29. Triton
    • -Neptune's moon
    • -Retrograde orbit: only large moon to do this
    • -Highly inclined relative to Neptune's equator
    • -Very young surface
    • -Thought to have tidal heating from Neptune
    • -Has a very thin nitrogen atmosphere
  30. Pluto
    • -39.9 AU from the sun
    • -Period: 250 years
    • -Retrograde rotation like Venus and Uranus
    • -Large eccentricity: .25
    • -Rock and ice
    • -.18 times Earth diameter
    • -Does not orbit on the same plane as real planets
    • -Moon: Chiron
    • -Is considered a trans-Neptunian object
    • -
  31. Kuiper Belt
    • -40-80 AU from sun
    • -Kuiper belt objects are made of rock and ice. Many comets originate here
  32. Asteroids
    • -Rocky bodies in orbit around the sun
    • -Leftover material from planetesimals that did not form partially because of Jupiter's gravity
    • -Without Jupiter, a planet would likely form there
    • -All smaller than 1000km
    • -Only the largest asteroids are round, most are shaped irregularly
    • -Some have moons
    • -Some made of rocky silicates, others may be carbon rich
    • -Some asteroids are low density because they are large piles of rubble loosely held together by gravity. They rotate slowly because high speeds would break them apart
    • -Near Earth Asteroids are those within the orbit of Mars
  33. Bode's Law
    • -Mathematical representation to predict the location of the semi-major axis of planets
    • -Not a scientific law, just a relationship
  34. Ceres
    • -A large asteroid, possibly the largest about 2.8 AU from sun
    • -Predicted by Bode's law
  35. Discovery of Neptune and Uranus
    • Uranus: First planet discovered by telescope
    • -Neptune: First observed by Galileo who thought it was a star. Discovered by John Couch Adams by using Newton's laws to observe gravitational forces on Uranus
  36. Kirkwood Gaps
    • -Like ring systems in planets with rings, gaps in the asteroid belt exist
    • -Also an effect of Jupiter's gravity
  37. Trojan Asteroids
    • -Asteroids that collect in the long-range points of Jupiter. Have the same orbital period as Jupiter
    • -50 Jupiter trojan asteroids known, 1 from Earth known
  38. Asteroid Impact Probability
    • -30 meter sized asteroids come close to Earth every 2 years and strike every 6,000 years
    • -Predicting asteroid paths is difficult because there are many variables
  39. Meteorites
    • -All are chunks of larger objects like the moon or Mars that are ejected and hit Earth
    • -3 categories: stony, stony-iron, and iron
  40. Stony Metiorites 420
    • -Most likely to hit Earth but are hard to find because they break apart
    • -Some are as old as the universe itself
  41. Stony-Iron Meteorites
    -Most rare to fall and to collect
  42. Iron Meteorites
    • -Less rare than stony-iron asteroids but easiest to find because the iron does not disintegrate as much on impact
    • -Were the most abundant source of metal to humans before mining
    • -Have the Widmanstatten pattern when broken apart. Produced when the iron-nickel mix slowly cools
  43. Differentiated Asteroids vs. Undifferentiated
    • -Undifferentiated: Random mix of iron and stone in a clump
    • -Differentiated: Have layers according to density like a planet does. Iron is core, stony-iron is middle layer, and stone is outer layer
  44. Chondrites
    • -Most abundant stony meteorite
    • -Primitive chemistry
    • -Formed when the Universe was formed
  45. Carbonous Chondrites
    • -Chondrites that contain water and organic compounds, whose presence means that the objects were not heated substantially
    • -Originate in solar nebulas
  46. Comets
    • -Solar system objects that orbit the sun and have a very high eccentricity. Usually not far from .99
    • -Only visible for a short time when they are near sun
    • -Outgassing is visible during this time due to particles reflecting sunlight
    • -When they are not passing the sun, they are hard to see b/c of a low albedo
  47. Short Period Comets
    • -Orbital period less than 200 years
    • -Life expectancy of 12,000 years
    • -Jupiter family comets: Orbital period less than 20 years
    • -Intermediate period comets: Orbital period of 20 to 200 years
  48. Long Period Comets
    -Comets with an orbital period of more than 200 years, although they typically exceed a period of millions of years
  49. Sun Grazers
    • -Comets that pass very close to the sun at perihelion.
    • -They can get up to 70 times closer to the sun than Mercury
  50. Origin of Comets
    • -Kuiper Belt: All comets in the short period comets section. Orbit on the same plane as the planets do
    • -Oort Cloud: All comets in long period comets section. They are distributed in a sphere and have random orbital inclinations. These comets are so far away they cannot be seen. They are disturbed by other star's gravity. Frequent observations of these comets indicates a large reservoir of comets in Oort cloud.
  51. Structure of a Comet
    • -Dust tail: points off to the side away from the sun and is slightly curved
    • -Ion Cloud: Directed away from the sun of and appears blue. It has charged H2O and CO molecules gathered from the solar wind
    • -Outer layer called a Coma and can be approx. a million km across.
    • -Inner layer, or Nucleus is a few km across
  52. Nucleus of a Comet
    -Solid objects, once thought to be dirty ice, but now show little sign of water ice.
  53. Meteor Showers
    • -Eventually, comets break apart and can form meteor showers
    • -When recently broken up, the particles will stay in orbit and eventually spread out to be particles in orbit like a ring
    • -On Earth, meteor showers happen when Earth passes through the remains of an extinct comet
  54. The Sun
    • -Takes light 8 minutes to reach Earth
    • -Takes solar wind a few days to reach Earth
    • -Surface temp: 5800 Kelvin
    • -333,000 Earth masses
    • -Obviously largest object in solar system by a long shot
    • -109 Earth diameters
    • -74% H, 25% He, 1% other. These elements are in the plasma state
    • -Simple molecules can only form in the photosphere where it is cool enough
    • -Solar minimum and maximum occur every 11 years
  55. Sun's Appearance
    • -With a filter, it is possible to see the sun's photosphere
    • -This allows you to see sun spots and the sun itself
    • -Corona: The part of the sun that is a plasma aura. It is the only part of the sun you see during a solar eclipse.
  56. Sun's Source of Energy
    • -Thermonuclear fusion, occurs because of the extreme pressures of the core, which fuse hydrogen protons to create helium. The lost mass is converted to the energy that is emitted from the sun.
    • -Enough energy for the sun to last another 5 billion years
  57. Solar Oscillations
    • -Like sound waves, the sun's energy oscillates.
    • -These oscillations can be observed and used to find rates of rotation, pressure, density, and chemical composition
  58. Layers of the Sun
    • -25% of the sun's diameter is the core, where thermonuclear fusion takes place
    • -The next layer, the radiative zone where the energy from fusion dissipates makes up 71% of the sun's radius
    • -The remaining radius is the convective zone, where the sun's energy emits out into space through convection
    • -Overturning bubble like motions in the sun occur and appear as grains in the sun. This action mimics a boiling pot of water.
  59. Solar Granulation
    • -Convective cells about 1000km wide
    • -Part of the sun's atmosphere known as the photosphere
  60. Layers of the Sun's Atmosphere
    • -Photosphere: The lowest layer where you see white light
    • -Chromosphere
    • -Corona: The outer plasma-like layer. It is very hot and continuously expands out into space
  61. Limb Darkening
    -The fact that the edges of the photosphere appear to be darker on the edges. This is because temperature decreases as you go up in the photosphere
  62. Sun Spots
    • -Lower temperature than surrounding area
    • -Darker part called umbra, lighter rim called penumbra
    • -Happen because of magnetic forces in sun
    • -Number of sunspots vary with what activity period the sun is in
  63. Zeeman Effect
    -The phenomena where you can determine magnetic fields using spectroscopy. If the spectral lines split, there is a magnetic field
  64. Sun's Influence on Earth
    • -Source of energy...yay
    • -Sun cycles occur every 11 years and influence how much energy Earth gets
    • -Solar particles bombard Earth and affect satellites and astronauts
    • -Solar winds cause aurora
    • -Seasonal variation, day-night, changes due to Earth's eccentricity
  65. Types of Solar Activity
    • -Solar Flares: Intense, brief flashes of X-rays from the sun
    • -Coronal Mass Ejections: A large eruption from the corona of the sun caused by magnetic disruption.
  66. Exoplanets: Methods to Finding
    • -Direct Observation
    • -Transits: When a planet passes in front of its star, it is easily detected
    • -Radial velocity: Spectroscopy. A star is observed using spectroscopy to see if it is red/blue shifted because of a planet's gravitational pull
    • -Gravitational force pulls on the star, giving evidence to the planet
  67. Exoplanets
    -Many exoplanets are larger than can be formed by their stars during solar system formation, so they must have migrated inwards after being formed elsewhere
  68. Maria and Highlands
    • -Maria: Darker and lower surface area of a body that is a result of volcanic flows. The maria is younger and is less cratered
    • -Highlands: Older, higher, and lighter colored part of a body. More heavily cratered
  69. Venus
    • -Venus exhibits phases because of its high albedo, high visibility, and the fact that its orbit is between the Earth and the sun
    • -Runaway Greenhouse Gas: The planet's heat vaporized the ocean, causing more water vapor to be in the atmosphere and further increasing the greenhouse gas effect. Phenomena is further compounded by volcanic outgassing.
  70. Mars
    -Opposition every two years because of orbital period and elliptical orbit