Astronomy test 1 vocab

  1. Astronomical unit
    the avg distance between the earth and the sun (93 million miles)
  2. Light Year
    the distance light travels in a year (6 trillion miles)
  3. Asterism
    an unofficial star picture
  4. Constellation
    88 different regions of the night sky
  5. circumpolar
    stars that never set ex: cassiopeia
  6. seasonal
    stars that do rise and set ex: Orion
  7. angular size
    Diameter, width
  8. angular seperation
    the distance between two points
  9. degree
    unit of measurement for angles, 60 arc minutes
  10. arc minute
    unit of measurement for angles, 60 arc seconds,
  11. arcsecond
    unit of measurement for angles, 60 arc seconds go into an arc minute-
  12. celestial sphere
    the imaginary sphere of celestial objects that seem to center on earth
  13. N + S celestial Poles
    projections of the earth axis on the celestial sphere
  14. celestial equator
    projection of earth's equater on the celestial sphere
  15. ecliptic
    apparant path of the sun across the celestial sphere
  16. zodiac
    the set of constellations the ecliptic passes through
  17. Prime Meridian
    0 degrees longitude located in greenwhich england
  18. horizon
    The line at which the earth's surface and the sky appear to meet
  19. zenith
    highest point in the sky
  20. altitude
    the distance north or south a point is from the celestial equator
  21. solstice
    the longest or shortest day of the year
  22. equinox
    2 days of the year when there is exactly 12 hours of daylight and 12 hours of night
  23. latitude
    measure of how far north or south you are from the equator
  24. longitude
    the measure of how far east or west you are from the prime meridian
  25. retrograde motion
    when planets appear to be moving backwards from the path across the ecliptic
  26. elongation
    the angle between a planet and the sun
  27. precession
    one of the three apparant motions of the earth; known as the wobble of the earths axis
  28. waxing
  29. waning
  30. synodic period
    when the moon is lined up with the sun from the earths point of view which takes 29.5 days between each one
  31. sidereal period
    true orbital period 27.3 days for the moon
  32. solar day
    noon to noon 24 hours
  33. sidereal day
    true rotational period; 23 hours 56 min
  34. synchronous rotation
    the moons orbit, where the rotational period and orbital period are equal
  35. tidal locking
    when one side of a body is always facing another, ie the moon to the earth
  36. eclipse season
    occurs approx every 6 months when the line of nodes points to the sun
  37. node
    the points where the moon's orbit crosses the ecliptic
  38. umbra
    full shadow
  39. penumbra
    partial shadow
  40. Annular Solar Eclipse
    when the moon is smaller than the sun and doesnt completely block out the sun. a ring is usually visible around the moon
  41. epicycle
    a circle in which a planet moves around; suggested by ptolemy to explain retrograde
  42. deferent
    A larger circle in which the epicycle revolves around
  43. geocentric
    the theory of the earth being at the center of the universe
  44. heliocentric
    the sun being at the center of the earth
  45. ellipse
    the shape in which the planets travel around the sun, not a complete circle
Card Set
Astronomy test 1 vocab
Astronomy 100 midterm