Starwatch: watch out for a man holding a snake

This time of year offers the opportunity to track down the large but faint constellation of Ophiuchus, the serpent bearer – literally a man holding a snake. One of the original 48 constellations listed by Ptolemy in the second century, there is no definitive association between the constellation and a myth, but several have been suggested. It could be Apollo grappling with the serpent that guarded the oracle of Delphi; or Apollo’s son Asclepius, who witnessed one serpent heal another by feeding it herbs; or maybe Laocoön, who was slain by sea serpents after he tried to warn the Trojans that the famous horse was a trap.

The chart shows the view looking south-west on Monday at midnight. To locate the constellation, first identify the bright star of Altair, in Aquila, the Eagle. Then look westward to Rasalhague, the brightest star in Ophiuchus, which will be considerably fainter. Finally, trace out the stars of the body in an anticlockwise direction: Cebalrai, Sabik, Saik, Yed Prior, and back up to Rasalhague.

Like Orion, the constellation straddles the celestial equator, making it easily visible from both hemispheres. Ophiuchus sometimes hits the headlines as the 13th sign of the zodiac. This is because its southern tip reaches down between Sagittarius and Scorpius, crossing the ecliptic, which is the path the sun follows around the sky each year. Since the ecliptic passes through all twelve of the zodiacal constellations, some followers of astrology believe Ophiuchus should be classified this way too.