Astro 1

  1. What are the unique aspects of astronomy?
    • It is observational, not experimental.
    • It is a historical science.
    • The scope of the field. (it studies the largest and smallest things in nature.)
  2. Units in Metric and English System
    Image Upload 1
  3. Stellar evolution
    changes in the stars caused by pulls of gravity.
  4. Milky Way Gallaxy
    a cloud of several hundred billion stars with a flattened dislike shape somewhat like that of the solar system.
  5. Light Year
    • 300,000 km/second
    • 186,000 miles/second
  6. superclusters
    collections of groups and clusters.
  7. Constellations
    How many?
    • a recognized grouping of stars
    • 88
  8. Asterisms
    • Unofficial groupings of stars.
    • Still remain in common use.
  9. Zenith
    point directly overhead
  10. celestial sphere
    • a distant starscape on the interior (of earth) with earth as its center.
    • Used to study stars from earth.
    • Stars are viewed as being the same distance away.
  11. Nadir
    • Point directly bellow you.
    • Opposite of the zenith.
  12. North and South CELESTIAL POLES.
    two points that do not more as the celestial sphere turns overhead.
  13. Celestial Equator
    • imaginary line directly above the earth's equator.
    • constellations on the celestial equator rise due east and set due west.
  14. local celestial meridian
    • line that runs from the north celestial pole to the south celestial pole.
    • divides earth east and west.
  15. ecliptic
    the path the sun traces across the celestial sphere.
  16. zodiac
    the collective group of constellations that the ecliptic crosses.
  17. Vernal equinox
    • when the sun is crossing the celestial equator.
    • March 20. from southern hemisphere to northern hemisphere
  18. autumnal equinox
    • september 22.
    • sun is crossing the celestial equators from north to south.
  19. Solstices
    • June 21, December 21
    • the sun stops it's northward or southward motion and begins to reverse direction.
  20. Short Term Motions in the sky.
    • Solar Day
    • 1 cycle
    • 24h00m00s
    • 360 degrees in 24h = 15 degrees/hr
    • 1 degree/4mins
    • appear to move eastward
  21. Short Term Motions in the sky
    • One cycle
    • lunar day
    • 24h50m00s
    • appear to move eastward
  22. Short Term Motions in the sky
    • 1 cycle
    • 23h56m00s
    • appear to move westward
  23. Short Term Motions in the sky
    each diurnal cycle varies in duration.
  24. Diurnal Motion
    Daily motions
  25. True Motions of the Earth:
    Apparent Motions:
    • Spinning of the earth on its axis...
    • rising/setting of the sun, moon, stars and planets
    • *diurnal/short term motions*
  26. True Motions of the Earth:
    • motion of earth around the sun...
    • 1 degree motion of the sun along ecliptic
    • 1 westward motion of the stars
  27. True Motions of the Earth:
    • change in orientation of earth's axis...
    • Polaris moving away from the NCP, no longer will be 'north stat'
    • changes in equatorial coordinates of stars
    • changes in seasons and constellations
  28. True Motions of the Earth:
    • wobbling of eath's axis...
    • celestial sphere wobbles N-S
    • 9'' per 18.6 years
  29. True Motions of the Earth:
    Barycenter Motion
    • true motion!!!
    • earth-moon motions...
    • moon revolves around earth
    • earth revolves around moon
    • they revolve about center of mass of system
  30. siderial day
    • day length, measured with respect to the stars.
    • siderial time.
    • 23h56m00s
  31. angular size
    how large things appear in the sky
  32. angular separation
    how far appart things appear in the sky
  33. arc minutes
    1 degree = 60' arc minutes
  34. arc second
    1' arc minute = 60'' arc seconds
  35. synodic period
    the amount of time it takes a body in the solar system to make an orbit relative to earth.
  36. sidereal period
    the length of time a body takes to make an orbit relative to the stars.
  37. Geographic coordinate system (earth)
    • Latitude (N-S)
    • Longitude (W-E)
    • geographic equator
    • NGP,SGP
  38. Thates of Miletus
    • predicted solar eclipse
    • invented astronomical navigation
  39. Pythagoras
    • presented model of the universe
    • central fire (sun) and 10 objects
  40. Aristotle
    • earth centered universe
    • earth didn't rotate, it was static
    • envisioned a spherical earth (shadow on moon)
    • correctly explained the phases of the moon
    • everything made from 4 elements (air, fire, water, earth)
  41. Aristarchus
    • measured sizes and distances of both sun and moon.
    • -moon smaller than sun, moon closer than sun
    • first to consider sun centered universe
    • argued that daily motions were a result of a rotating earth.
  42. Eratosthenes
    acurately deduced the circumference of the earth
  43. hipparcus
    • devised the first star catalogue
    • it included 800-1000 stars
    • estimated moon's distance and size accurately
    • measured the length of a year- plotted sun on ecliptic over this year
  44. Claudius Ptolemy
    • "Great Syntaxes of Greek Astronomy"
    • 13 volume book that says everything we know about greek astronomy.
  45. Anaxagoras
    • first person to explain eclipses
    • pictured moon and planets as earthlike.
    • -solid crusty surfaces shinning by reflected sun light.
  46. retrograde motion
    when planets move west with respect to the stars.
  47. cosmology
    • study of the origin and nature of the universe.
    • geocentric-earth centered
    • heliocentric- sun-centered
  48. planets move in an epicycle and a deferent.
    the epicycle is a smaller cycle which in turn moves along a bigger circle, deferent.
  49. direct motion v. retrograde motion of planets
    • direct motion is counter clockwise. (actual motion-west)
    • retrograde motion is clockwise. (eastward)
  50. theory
    well developed or well rested hypothesis or set of hypotheses that have been verified.
  51. hypothesis
    single assertion or conjecture that must be tested.
  52. model (law)
    theory that accounts for a set of observations in nature.
  53. scientific model
    • hypothesis > theroy > model
    • must fit data (observations)
    • must make predictions (can be tested)
    • aesthetically pleasing.
  54. prolemaic cosmological system
    • flat system
    • geocentric - earth in the center
    • explained the motion of the planets using epicycles and deferents
    • planets move counter clockwise in both.
  55. copernican cosmological system
    • flat system
    • put the sun rather than earth at the center
    • planets closer to the sun move faster than those further away
    • argued that retrogade motion was because of the motions of the combined motions of the earth and other planets
  56. Tycho Brahe
    • "castle in the sky"
    • best naked-eye observer of his time
    • worked with Kepler to make his own model of the universe.
  57. Johannes Kepler
    • employed by Brahe
    • 3 laws of planetary motion
  58. Kepler's Law:
    Law of Elipses
    planets orbit the sun in elliptical orbits (cone example- oval shape ellipses) with the sun located at the center (focus)
  59. Kepler's cosmology:
    major axis
    largest diameter of ellipse
  60. Kepler's cosmology
    minot axis
    smallest diameter of ellipse
  61. kepler's cosmology
    semi-major axis
    half of the major axis
  62. kepler's cosmology
    semi-minor axis
    half of the minor axis
  63. Kepler's Law:
    Law of Areas-Speeds in orbit
    • planets move in equal areas in equal time around the sun.
    • in order to do this, they must move faster when they are closer to the sun and slower when further away.
  64. Kepler's Law:
    Harmonic Law- yardstick of the solar system
    • 8 musical notes (sun, moon, earth and 5 naked eye planets)
    • able to measure relative distace of all naked eye planets from the sun.

    the square of a sidereal period of a planet is directly proportional to the cube of its semi-major axis.
  65. Galileo Galilei
    • first naked-eye astronomer to look at the heavens with an astronomical telescope.
    • published "the starry messenger"
  66. Galileo Observation:
    Milky way
    it was made of thousands of stars
  67. Galileo Observation:
    has craters, mountains, valleys and seas
  68. Galileo Observation:
    has dark blotches on it which he called sunspots
  69. Galileo Observation:
    wasn't round, it had ears.
  70. Galileo Observation:
    went through a series of phases just like our moon.
  71. Galileo Observation:
    had four star-like objects revolving around it.
Card Set
Astro 1
Astronomy test 1.