What is the 13th constellation? Not many people know about Ophiuchus (pronounced “Oh-few-cuss”), the serpent bearer, a vast constellation of summer — but they should. Not only is it sizeable, but by rights, it should be a star sign because, like Leo, Aquarius and Sagittarius, it’s on the zodiac.
This week is ideal for finding Ophiuchus in the night sky, with today — the date of the new moon — the best night. With the moon lost in the glare of the sun, the night sky will be moonless.
What Is Ophiuchus?
One of the zodiac’s most overlooked constellations, Ophiuchus, is an ancient star pattern that sits between the better-known constellations of Scorpius and Sagittarius. Like the 12 zodiac signs celebrated in horoscopes, the sun passes through Ophiuchus from Nov. 29 to Dec. 18 each year.
Where And When To Look
Head out after dark on July 24 — or anytime this week when the moon is not in the sky — and look toward the south. In between the prominent stars of the Summer Triangle (above) and the stinger of Scorpius (below) is Ophiuchus. Its stars are fainter, but with dark skies, they’re within reach — particularly if you observe from away from light pollution. The easiest way to see Ophiuchus is to begin by finding Rasalhague, its brightest star.
What You’ll See
Ophiuchus isn’t very bright, but it stretches impressively across the summer sky. Its brightest star, Rasalhague, lies near the top of the constellation and shines at magnitude 2.1 — bright enough to catch the eye. If you’re familiar with the Summer Triangle, try adding Rasalhague as a fourth point to create a “Summer Diamond” pattern.
While you won’t be able to see it, inside the stars of Ophiuchus is Barnard’s Star, which, at six light-years from the sun, is the fourth-closest star system to our own.
What’s Next In The Night Sky
On Friday, July 25, skywatchers have a rare chance to spot a 2%-illuminated waxing crescent moon just after sunset. It will be low in the northwest and begin a string of evenings when a crescent moon will shine after sunset, rising a little higher and becoming a little brighter with each passing night.
For exact timings, use a sunrise and sunset calculator for where you are, Stellarium Web for a sky chart and Night Sky Tonight: Visible Planets at Your Location for positions and rise/set times for planets.
Wishing you clear skies and wide eyes.