This whole "new Zodiac sign" thing is a joke, folks. Or rather, another attempt - as if any were needed - to discredit astrology (it's been going around for decades - I wonder why it is just hitting the news suddently? Is the Amazing Randi doing a tour?).
It is partly disingenuousness, and partly trying to get astrologers to recognize the Precession of Equinoxes (some do, called "Sideral Astrologers", and, I think, Jyotish (Indian) Astrology).
The boundaries of the constellations were settled only in the 1920s by the International Astronomical Union (IAU). The path of the ecliptic (the apparent line along which the Sun travels through the Zodiac in a year) does not perceptibly change because of Precession - it has always traveled through this part of space. All that has changed is that now the "official" boundary of what Ophiuchus should be now includes an arbitrary amount of space including a large part of the ecliptic between Scorpio and Sagittarius; and, because of Precession, the actual position of the Sun at the Vernal Equinox (now about 5° Pisces instead of the traditional 0° Aries).
These two issues should not be confused. That is, the arbitrary definition of which stars to include in a constellation and its arbitrary modern boundaries; and, the Precession of Equinoxes.
Precession does NOT change the position of the ecpliptic (perceptibly) relative to the background stars. Precession is due to a "wobble" in the Earth's rotation on its axis; this wobble is due to the combined gravitional effects of the Moon and Sun on the Earth; it takes about 26,000 years for this wobble to make a complete circle around the axis. Think of a spinning top, which leans slightly as it spins. It spins around its own axis, but also makes a turn around an invisible central axis that would correspond to exact verticality.
The ancient astrologers who made the twelve signs of the Zodiac did not recognize the bottom part of Ophichus as part of another constellation (the only bright star there anyway is Theta Ophiuchus, a 17th century definition); the ecliptic for them, as for modern astrology, goes from Scorpio to Sagittarius.
Skeptics trying to throw a wrench into astrology might use better not only precession and modern IAU constellation boundaries, but the ancient boundaries themselves - Aries is a tiny Zodiac sign, while Virgo is about 10 times larger in length along the ecliptic. But both are assigned 30 degrees, to maintain the symmetry of the 12-sign Zodiac.
Ross
