Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Constellation of date and the actual constellation that follows the sun

  1. Sep 24, 2010 #1
    Each month a different zodiac constellation follows around the sun day and night.

    The constellation is in the house of the zodiac sign but the actual constellation is the zodiac before.

    Example: the constellation of date is Libra but the constellation that follows the sun around is Virgo.

    My question is what is the angle difference between the actual and when original constellation of date went around the sun.
    Last edited: Sep 24, 2010
  2. jcsd
  3. Sep 27, 2010 #2
    There are two major forms of signs. The Tropical zodiac and Sidereal zodiac

    The Sidereal signs set their dates relative to the Earth's position within the Galaxy.

    The Tropical signs are dependent upon the vernal equinox (seasons) to set dates.

    The different stabilities of these two sources for the signs are causing them to drift apart over time.

    Also, the Constellations do not travel around the sun. They appear to move because of the Earth's relative position which changes the backdrop behind the Sun.
    Last edited: Sep 27, 2010
  4. Sep 27, 2010 #3
    Oh and after checking wiki (I know, an excellent source), the two signs drift apart at 1.4 degrees per century.
  5. Sep 28, 2010 #4
    So you plug in any RA and DEC the regression will be 1.4 degrees per century. That will be its position however many centuries ago.
    Last edited: Sep 29, 2010
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook