astronomy chapter 1

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astronomy chapter 1
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2013-08-25 20:07:42
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astronomy 100
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  1. Newtonian Mechanics
    Issac Newton deduced a set of fundamental principles that describe how all objects move
  2. Laws of Physics
    Newtonian mechanics and other physical theories have stood to the test of time and general validity. Proven theories of this kind are collectively referred to as the laws of physics.
  3. Earth-Sun distance
    150,000,000 km 1.5 x 10^8 km = 1 astronomical unit (AU)
  4. 1 light year
    • distance that light travels in one year
    • 9.46 x 10^12 km = 63,240 AU
  5. 1 parsec
    3.26 ly
  6. 1 megaparsec (Mpc)
    1000 kpc = 10^6 pc ; the average distance between galaxies is about 1 Mpc
  7. Distance to the edge of the observable universe
    4200 Mpc = 13.7 ly
  8. Carina Nebula
    spans over 300 light years lies about 7,500 light years away in the constellation of Carina. New stars form in dark (dense) clouds
  9. solar system
    The star we call the Sun and all the celestial bodies that orbit the Sun including the other planets all their various moons and smaller bodies such as asteroids and comets
  10. supernova
    Some stars that are far more massive than the Sun end their lives with a spectacular detonation
  11. pulsars
    dead stars which spin rapidly at rates of tens or hundred of rotations per second
  12. black holes
    some stars end their lives as dense objects whose gravity is so powerful that nothing even light can escape. A number of black holes have been discovered by Earth-oribiting telescopes by detecting the X Rays emitted by gases falling toward a black hole.
  13. galaxies
    stares are grouped together in huge assemblages
  14. quasars
    most distant and most luminous objects in the sky (mysterious)
  15. expounding
    motions of distant galaxies reveal that they are moving away from us
  16. big bang
    the universe began with a cosmic explosion which occrued throughout all space
  17. angle
    the opening between two lines that meet at a point
  18. angular measure
    describes the size of an angle exactly
  19. angular distance
    angle between two pointer stars
  20. angular diameter (angular size)
    how wide the object appears on the sky 

    moon is 1/2 degree
  21. arcminute
    1/60 of a degree
  22. arcseconds
    1/60 of a minute
  23. What does it mean to say the moon subtends an angle of 1/2 degree
    we mean angular width is 1/720 of the circle
  24. whats the difference between a solar system and a galaxy
    A solar system is a star and with planets and other orbiting objects. A galaxy is an enormous grouping of gravitationally bound stars and other objects.
  25.   what makes the sun and stars shine
    thermonuclear fusion
  26. small angle formula
    linear size of an object (D) = (alpha)angular size x distance to object (d) /206,265

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