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RA and Declination

  1. Jan 26, 2008 #1
    Can anyone explain how to graph Right Ascension and Declination on a globe graph?
  2. jcsd
  3. Jan 26, 2008 #2
    Do you know how longitude and latitude are plotted on a globe? Right Ascension is like longitude and Declination is like latitude.
  4. Jan 26, 2008 #3
    I understand that it is like longitude and latitude, but if I am presented with a blank map of the night sky and am asked to find what is at some number RA and Dec, how do I start, RA or Dec? And, does it matter where I am starting from?
  5. Jan 29, 2008 #4
  6. Jan 29, 2008 #5


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    What do you mean, a "blank map?" How is a blank map useful?

    If you're given a map with coordinates on it, all you need to do is... find the spot with the given coordinates. You can start with either coordinate first. When you find the right RA, you've found a specific line of "longitude." You can then follow that line until you find the given declination.

    - Warren
  7. Jan 30, 2008 #6
    The zero-point on the RA and Dec grid is the first point of Aries (the location of the sun in the sky on the Vernal equinox). RA follows the direction of the celestial equator (the projection of Earth's equator in the sky) and Dec goes perpendicular to that.
  8. Jan 30, 2008 #7
    The teacher gave us a blank circle with the Vernal Equinox line and the Celestial Equator listed, no other grid lines or way to measure degrees and said put a dot at the such and such RA and Dec points. Is it just me or was this kind of crazy?
  9. Jan 30, 2008 #8


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    You could always estimate, but you might not be very accurate.

    - Warren
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