By early next week the evening sky is free of the moon. A good time to see Ophiuchus the Serpent Holder is at 9 p.m. near Scorpius the Scorpion.
Ophiuchus is a man holding a large snake represented by Serpens Caput (head) on its western end and Serpens Cauda (tail) on its eastern. Ophiuchus the constellation is a misshapen oval of about 10 brighter stars with lines of stars (the Serpens) on either end.
Ophiuchus is most deserving of our attention because it and Serpens Cauda are contiguous to the western edge of the Milky Way.
Ophiuchus is also one of the 13 constellations that cross the ecliptic โ the apparent path in the sky the sun follows on its yearly journey. Most of the planets are close to the ecliptic, and their paths around the sky are confined to the narrow zone known as the zodiac, which stretches about 9 degrees on either side of the ecliptic.
The โsigns of the zodiacโ were established with 12 constellations several thousand years ago when astrology and astronomy were closely related.
Over time, the two disciplines have gone their separate ways. Formal constellation names and boundaries were standardized by the International Astronomical Union (IAU) in 1933 to prevent confusion. This was how the zodiac gained a 13th constellation, Ophiuchus, because its modern boundary overlaps the zodiac.
