Zodiac Help

  • Danny_C

    Danny_C - 2012-05-22

    Hi guys, I’m a bit of a newbie to astronomy and I’m just trying to figure out
    some fundamental basics.

    I know that each sign of the zodiac occupies 30 degrees of the ecliptic and
    this in turn equates to 2 hours of Right Ascension, all adding up to 360
    degrees and 24 hours. All good so far.

    So I start at the start: 0 hours Right Ascension, March 20th, exactly where
    the sun crosses the line at dawn. The puzzling thing is, instead of being at
    the start of Aries(given as March 21st – April 19th),the sun is rising in
    front of Pisces and continues to do so until April 21st.

    It seems that the dates officially given for each sign of the zodiac are ahead
    of what is actually happening by a month.
    Can someone please help explain why or point me in the right direction? I
    would be very grateful.
    Many thanks,

  • qam1

    qam1 - 2012-05-22

    Astrology is a fraud, those dates in your daily horoscope haven't been valid
    for 2000 years now



  • Anonymous - 2012-05-25

    The tropical zodiac is made up of 12 signs - and _not _ the constellations. It
    is a coordinate system that covers the entire sky with each sign extending
    from the north ecliptic pole to the south ecliptic pole rather like slicing an
    orange twelve-fold with signs sweeping out slices across the sky (like hours
    of RA do) .

    Thus the signs are celestial geometry and constellations are the stars
    patterns from which the signs have adopted their names.

    Since the signs and the RA system are anchored to the same equinox they are
    subject to precession causing the signs to slip away from their original
    constellation namesakes over the last 2000 years.

    Like the RA system the signs begin at the equinox with sign Aries (not
    constellation). All celestial objects in the sky therefore have a zodiacal
    position in a sign with an accompanying zodiacal longitude and latitude. Thus
    the star Alkaid in Ursa Major is currently in the sign Virgo at 27 degrees and
    zodiacal latitude 55N.

    Because the equinox is subject to precession both the RA system ad the
    tropical zodiac system slip westward over time. so that the original
    constellations from which the signs adopt their names have now some 30 degrees

  • Danny_C

    Danny_C - 2012-05-31

    Wow! Thanks.

    I guess the million dollar question is - WHY hasn't this been adjusted in over
    2000 years to match the current positions?

    Any ideas?

  • Anonymous - 2012-06-01

    It's so much why was it not adjusted, it's that astrologers chose to use the
    tropical zodiac rather than the constellations probably because the tropical
    zodiac is synchronised with the seasons (anchored to the equinoxes and
    solstices). It is of interest to note the likes of Copernicus, Galileo and
    Kepler who were very well versed in celestial geometry also cast horoscopes in
    the tropical zodiac. They would have been very well aware of precession



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