Ophiuchus: The 13th Zodiac Constellation Explained

If you’re in the Northern Hemisphere, look southward on July, August or September evenings for mighty Ophiuchus the Serpent Bearer. Chart via Chelynne Campion/ EarthSky. Ophiuchus, the Serpent Bearer: An Unofficial Zodiac Constellation Did you...

Star chart: Constellation Ophiuchus with parts labeled above red supergiant star Antares. If you’re in the Northern Hemisphere, look southward on July, August or September evenings for mighty Ophiuchus the Serpent Bearer. Chart via Chelynne Campion/ EarthSky.

Ophiuchus, the Serpent Bearer: An Unofficial Zodiac Constellation

Did you know that if you were born between November 30 and December 18, your "sign" should technically be Ophiuchus? However, Ophiuchus is not officially recognized as a constellation of the zodiac. Even though Ophiuchus the Serpent Bearer is a large constellation visible from the Northern Hemisphere during July, August, and September evenings, it does not make its way into horoscopes. The unofficial boundary lines drawn up by the International Astronomical Union (IAU) in the 1930s excluded Ophiuchus from the zodiac lineup.

Ophiuchus and the Zodiac Signs

Ophiuchus often gets overlooked despite the fact that the ecliptic, the apparent path of the sun, passes through it. The zodiac band extends approximately 8 degrees north and south of the ecliptic, spanning a width of 16 degrees. While the 12 familiar signs of the zodiac are widely recognized in astrology, Ophiuchus does not find a place among them. However, both the moon and planets regularly move within the boundaries of this constellation, including the sun. In fact, the sun is in front of Ophiuchus from November 30 to December 18 each year, even though it is considered to enter the sign of Sagittarius around November 21.

Antique color etching of old bald bearded man in ancient Greek garb holding a long writhing snake. Ophiuchus holding the serpent, Serpens, as depicted in Urania’s Mirror, a set of constellation cards published in London circa 1825. Image via Adam Cuerden/ Wikipedia (public domain).

Locating Ophiuchus in the Sky

To observe Ophiuchus, the best time is during a Northern Hemisphere summer (Southern Hemisphere winter). In late July and early August, this constellation rises high in the southern sky at nightfall and early evening. In the Northern Hemisphere, it can be found in the southwest sky on autumn evenings. Ophiuchus lies to the north of Scorpius the Scorpion and to the south of Hercules the Strongman. Star-hopping from Scorpius' brightest star, Antares, will lead you to the head of Ophiuchus, marked by the star Rasalhague (Alpha Ophiuchi). The constellation's shape even resembles a big man holding a snake, making it easily identifiable in a dark sky.

Deep-sky Objects and Ophiuchus' Mythological Connections

Ophiuchus is a treasure trove for stargazers, especially on moonless nights. Look through binoculars, and you'll discover numerous globular clusters, such as M10 and M12. These clusters appear as faint puffs of light, but with a telescope, you'll witness the vastness of these stellar cities, teeming with hundreds of thousands of stars. Another captivating sight is the Pipe Nebula, a dark interstellar cloud of gas and dust that stretches across about 7 degrees of the sky. It can be seen with the naked eye in a dark, transparent sky. Ophiuchus also has a rich mythological background. In Greek lore, it represents Asclepius, the god of medicine and doctors, who is often depicted holding a great serpent. Legends tell of Asclepius using the venom of Serpens the Serpent to create a healing potion, granting humans access to immortality. Zeus, concerned about the consequences, placed Asclepius among the stars and immortalized him as Ophiuchus the Serpent Bearer.

Ophiuchus in History and Science

Ophiuchus played a significant role in challenging ancient Aristotelian beliefs about the universe. In 1604, Kepler's Supernova, which exploded in southern Ophiuchus, defied the prevailing notion of an unchanging universe beyond the moon. This supernova, along with Tycho's Supernova in 1572, shook the European intelligentsia and provided evidence against the Aristotelian worldview. Additionally, Ophiuchus takes part in the zodiac for about two weeks each year, marking its unofficial membership. As scientific understanding deepens, we continue to unravel the mysteries of this fascinating constellation.

The Constellations of the Zodiac

While Ophiuchus might not be officially recognized as a zodiac constellation, the 12 established constellations remain beloved fixtures in astrology. From Aries the Ram to Pisces the Fish, each constellation has its own distinct characteristics and stories.

So, next time you gaze at the night sky, take a moment to appreciate the celestial wonders and the intricate mysteries that lie within Ophiuchus and its neighboring constellations.