Astronomy 2

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Astronomy 2
2011-03-29 20:29:29

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  1. What are the most importanat (geological) processes involved in the shaping of planetary surfaces?
    • volcanism- volcanoes and volcanic eruptions
    • meteor impacts- craters
  2. What are some of the different types and characteristics of impact craters, and how do they relate to the size of the impacting object?
    • craters form 20 times bigger than the object that caused the crater
    • 1. punch bowl/simple crater- smallest, usually caused by objects less than 1 mile in diameter
    • 2. central-peaked crater- group of mountains in middle of crater, created by objects 1-5 miles wide
    • 3. multi-ringed impact basin- largest, multiple rings spread out from center, at least 5 mile wide impacter
  3. How can one use impact craters to estimate the age of a planetary surface?
    crater count- counting amount of craters in an area and dividing that number by the area
  4. What are some of the effects that a meteor impact would have on earth?
    • produce a crater
    • blast huge amounts of dust and molten rock into the air
    • molten rock raining down would raise the surface temp extremely high causing global wildfires
    • hot fragments and blast would create nitrogen oxides which would combine with water to form nitric acid rain
    • the toxic combination of heat, acid rain, and blast would be followed by months of darkness and intense cold caused by the dust shroud blotting out the sun
  5. What role does volcanism and erosion play in the shaping of planetary surfaces?
    • erosion- wears away rock and other surface materials (if the earth had no geological activity to rebuild mountains, the action of rain, flowing water, and waves would have gradually ground down the earth until the entire surface would be under water)
    • volcanoes- lava flows smooth out the surface
  6. Lava plain/mare
    • smoothed out areas on moon that are completely devoid of water
    • largest volcanic feature
    • flood basalt
  7. Olympus Mons
    • largest volcano is solar system
    • found on Mars
    • shield volcano (most common)
  8. Shield volcano
    • most common
    • least violent eruptions
    • large craters in center (caldera), irregularly shaped unlike impact craters
  9. Caldera
    • large crater in center of shield volcano
    • irregularly shaped unlike impact craters
  10. Chicxulub Crater
    180 km (110 mile) wide crater found in Yucatan region in Mexico
  11. Magnetosphere
    the region of space surrounding a planet where its magnetic field deflects away the solar wind
  12. Bow shock
    the area between a magnetosphere and an ambient medium
  13. Magnetopause
    the abrupt boundary between a magnetic field and surrounding plasma
  14. Magnetic tail
    formed by pressure from the solar wind on a planet's magnetosphere
  15. Geologically dead planet
    • no heat left
    • no volcanic activity
    • no plate tectonics
  16. Geologically active planet
    • some heat left, still hot inside
    • volcanoes, quakes, plate tectonics still occur
  17. Mercury's day and year
    • solar day- 176 earth days
    • orbital period (year)- 87.969 earth days
    • rotation period- 58.646 earth days
    • spins three times for each two trips it makes around the sun
    • the day is longer than the year
  18. Why is Mercury probably made mostly of iron?
    • the iron core is based on its density
    • although a massive planet's gravity can compress its interior to high density, Mercury is too small for this effect to be significant. therefore its high density indicates an iron-rich interior with only a think rock mantle
  19. Lobate Scarps
    • giant (mile high) cliff on Mercury and the moon (but not as big)
    • the planet cooled and shrank, wrinkling, crust collapsed into mantle causing scarps
  20. Why doesn't Mercury have an atmosphere?
    • its gravitational attraction is too weak to retain any significant amount of gas
    • its closeness to the sun makes its temp higher which in turn causes any gas molecules there to move so rapidly that they readily escape into space
  21. Why does Mercury probably have a magnetic field?
    • a magnetic field is generated by circulation of electrically conducting material in a planet's interior
    • mercury is too small to have a molten core therefore, the outer iron core may be mixed with sulfur which can lower the melting temperature
  22. Why might Venus have such a slow rate of rotation?
    Venus had a faster retrograde spin in the distant past and the sun's tidal effects slowed it down to its current rate
  23. What is the dominant geological process affecting Venus' surface?
  24. Aphrodite Terra
    • highland region on Venus
    • located near Venus' equator
  25. Ishtar Terra
    • highland region on Venus
    • studded with volcanic peaks
  26. Mons Maxwell
    • volcanic peak on the ishtar terra of Venus, including tallest volcano
    • only male name on Venus
  27. Coronae
    large, crown-like volcanic features on Venus
  28. What is the composition and some of the properties of Venus' atmosphere?
    • 96.5% C, 3.5% N, trace amounts of water vapor and other gases
    • lightning storms, but no rain
    • clouds composed of sulfuric acid droplets
    • clouds permanently cover the planet and are very high and thick (cannot see through them with ordinary telescope)
    • below clouds, atmosphere is relatively clear and some sunlight penetrates to surface
    • pressure 90 times that of earth's
    • >900 degrees F, 500 degrees C
  29. Runaway Greenhouse Effect
    • greenhouse effect- heat enters the atmosphere, but does not leave
    • heating has driven the temperature up, and the heating has led to an even stronger greenhouse effect
    • happened to Venus (Venus' surface is hotter than Mercury's even though it is further from the sun)
  30. Does Venus have a magnetic field?
    • no. it does not have a dynamo which requires a conducting liquid, rotation, and convection
    • Venus lacks convection in the core
  31. What sort of tectonics occur within the earth?
    • convection- circulating movement of a heated liquid or gas
    • rifting- the mantle stretches and spreads the crust, breaking apart
    • subduction- one plate is driven back down into the mantle
    • volcanoes
    • earthquakes
  32. What are the dominant physical processes that shape the earth's surface?
    • plate tectonics
    • convection
  33. In what ways is the earth different from the other planets?
    • atmosphere is 80% N2 and 20% O2
    • it currently has plate tectonics
    • it's livable
  34. What is the composition and some of the properties of earth's atmosphere?
    • 80% N and 20% O
    • troposphere- dense lowest layer of atmosphere where water vapor circulates, clouds form, and the air is very turbulent
    • stratosphere- stable layer above troposphere which contains gases such as ozone to shield the earth's surface from most of the short-wavelength radiation from space
    • inonosphere- where most molecules and atoms have been broken apart into ions
  35. Why does the earth have a powerful magnetic field?
    it has a magnetic dynamo process which is generated by electric currents flowing in its molten iron core
  36. What are the dominant two types of surfaces on Mars and where do they occur?
    • southern cratered highlands
    • northern lowlands
  37. What type of tectonics may occur within Mars, and what are the dominant physical processes that shape/have shaped Mars' surface?
  38. Tharsis bulge
    an uplands region spanning the equator of Mars about the size of North America
  39. Valles Marineris
    • an enormous rift along the equator of Mars
    • would span the continental US
  40. What is the composition and some of the properties of Mars' atmosphere?
    • 95% CO2 and 3% N with traces of O and H2O
    • similar to Venus' but far less dense
    • -80 to -140 degrees F
    • clouds made of dry ice and water ice crystals
    • no rain
    • thinned due to: weak gravity, ablation, dry ice
  41. In what ways has water and ice played a role in Mars' past and how may they play a role now?
    Mars may have had a denser and warmer atmosphere in the past, allowing liquid to exist. when Mars lost it's atmosphere cause the planet to plunge into a permanent ice age. gas molecules escaped and water molecules evaportaed. as Mars cooled, the remaining water froze solid and wind buried the ice under protective layers of dust
  42. Does Mars have seasons?
    yes. it's axial tilt produces a pattern of seasons similar to earth's, but more extreme because the atmosphere is much less dense
  43. What is Jupiter primarily composed of?
    90% H, 10% He
  44. Why is the atmosphere of Jupiter so turbulent?
    it has deep circulation (convection currents carry warm gas upward and into space, as it cools, it sinks back down) and rapid rotation
  45. What are some of the different compositional types of clouds that occur in Jupiter's atmosphere?
    • ammonia ice
    • ammonium hydrosulfide
    • water
  46. Zones
    • whitish yellow bands of clouds made of ammonia ice
    • found on jupiter
  47. Belts
    • dark orangeish brown bands of clouds made of ammonium hydrosulfide
    • found on jupiter
  48. The great red spot
    • turbulent storm, twice as big as earth
    • high pressure system unlike hurricanes and cyclones
    • found on jupiter
  49. Why does Jupter have such a powerful magnetic field?
    convection in the metallic liquid hydrogen combines with the planet's rapid rotation which is driven by a natural dynamo process
  50. Does jupiter have a ring?
    • yes
    • narrow "bright" ring (main) with sparse, broad rings (Gossamer Rings)
    • composition- dust
  51. Shepherd moons
    maintain rings, prevents particles from spreading out and dispersing
  52. How many moons does jupiter have and where did they come from?
    • 63
    • they aggregated from planetesimals and gas that collected around the gas giant during formation or were captured after passing by closely to the planet
  53. In what ways is Saturn similar to Jupiter in terms of internal structure, composition, and atmosphere?
    • 96% H and 3% He
    • cloud composition is ammonia and water
    • has shepherd moons orbiting amongst rings
    • turbulent storms
    • oblate spheroid (egg-shaped)
    • 62 moons
  54. What are the differences between Jupiter and Saturn?
    • Saturn has less prominent zones and belts
    • Saturn has more rings
  55. What are the rings of Saturn composed of?
    countless small particles made of ice and dust
  56. How many moons does saturn have?
  57. In what ways is Uranus distinct from Jupiter and Saturn?
    • half the size of Saturn
    • tipped on side
  58. What is the composition of Uranus' atmosphere and why is it blue-green?
    • rich in hydrogen and helium and 2% methane
    • methane gives it it's color
  59. Why does Uranus possibly lie on its side?
    a giant impaact