Ophiuchus
Ophiuchus, gripping a great serpent in both hands. It is the "thirteenth constellation" the Sun truly passes through, and Asclepius, the god of medicine who raised the dead.
Science
The scienceOphiuchus straddles the ecliptic, so the Sun actually passes through it for about 18 days from late November each year; yet when the ancients divided the ecliptic into twelve, it was left out, earning the name "the thirteenth constellation." Around its large pentagonal body it holds, to either side, the head and tail of Serpens (the Serpent), making it the only constellation in the sky that splits another in two. In this direction lies "Barnard's Star," the second-nearest stellar system to the Sun; and in 1604 a supernova observed by Kepler (SN 1604) blazed here, recorded as the last supernova within our Milky Way seen with the naked eye.
Mythology
How it became a constellationOphiuchus depicts Asclepius, the greatest physician of Greek myth. Having learned medicine from the centaur Chiron, he watched two serpents bring healing herbs to each other to revive a fallen companion, and so mastered the secret of raising even the dead. But Hades, lord of the underworld, fearing that the order of the world would collapse if humans no longer died, protested to Zeus, who struck Asclepius down with a thunderbolt. In honor of his great skill, Zeus set him in the sky as a constellation, serpent in hand. The "staff entwined with a serpent" that he holds is used as the symbol of medicine to this day.
Observing Guide
how to observe🔭 How to find it
In the summer southern sky, above the red star Antares (in Scorpius) and below Hercules, a broad pentagon marks the body of Ophiuchus. Its head star, the bright Rasalhague, stands out just south of Vega, so start there and draw a large pentagon downward. This unusual figure holds the head and tail of the serpent (Serpens) separately, one on each side of the pentagon.
✨ What to look for
Ophiuchus lies toward the center of our galaxy, making it a treasure trove of globular clusters. Notably, M10 and M12 sit close together inside the pentagon, perfect for framing and comparing in one field of view, and several more bright globulars — M9, M14, M19, M62 — are scattered about. Barnard's Star, the second-closest star to the Sun, also lies in this direction.
📍 Where to see it (US · Canada · UK · Australia)
Ophiuchus spans declinations from about +12° down to −30°, so from the US, Canada, and the UK the large pentagon of its body rises fairly high in the south on summer nights (June–September), while its southern reaches — and the globulars M19 and M62 — hug the horizon. From Australia the whole figure rides high during the southern winter, and those southern clusters that merely skim the horizon up north pass nearly overhead.