Constellational odd couple: Ophiuchus, Serpens


By Tom Burns - Stargazing



Of all the constellations, none is stranger than the combination of Ophiuchus, the Snake Wrestler, and Serpens, the snake he is wrestling with.

For one thing, Serpens is the only non-continuous constellation. The body of Ophiuchus separates Serpens Caput (the serpent’s head) on the right from Serpens Cauda (the serpent’s tail).

Ophiuchus is most often identified as Asclepius, a mythological physician, who seems oddly engaged in a death struggle with a giant serpent.

The brightest star of Ophiuchus is still called Rasalhague, a corruption of the Arabic name Ras al Hawwa, the “Head of the Serpent Charmer.” How did the noble physician end up wrestling a snake?

Look for the constellational odd couple low in the south just after dark. You’ll find it in the southeast by around 11 p.m. It occupies the space between the more familiar constellations Hercules (above) and Scorpius, the Scorpion (below).

Let’s start with the snake. Serpens, combined with some stars of Ophiuchus, was seen as a snake as far back as biblical times. Many cultures, notably the Hittites and the Hebrews, near the Euphrates River did so.

In ancient Arabia, several stars we now associate with Serpens and Ophiuchus were merged with stars in nearby Hercules to form a peaceful, pastoral scene.

Rasalhague, the brightest star in Ophiuchus, was combined with a few faint stars nearby to form Al-Rai, the Shepherd. Alpha Herculis, the brightest star in Hercules, was the shepherd’s dog. Some fainter stars of Hercules became the “Flock of Sheep.”

Later, Arab scholars adopted the Greek versions of the constellations wholeheartedly. The shepherd, his loyal dog, and his peacefully grazing flock became the rather violent Hercules and an ancient physician wrestling with a snake.

The constellations’ histories have been marred by political considerations as well. Such is the case of the stars surrounding the star marked #70 Ophiuchi on most star maps.

In 1777, Polish astronomer Abbé Poczobut asked the French Academy to honor the last Polish king, Stanislaus Poniatowski, with a constellation of his own. Such requests were common in those days. Scientists were always trying to acquire financial support from rich and powerful patrons.

The French Academy came through. Taurus Poniatovii, Poniatowski’s Bull, was born.

Poniatowski’s Bull consisted mainly of a v-shaped collection of stars dominated by #70 Ophiuchi. Savvy astronerds will surely notice that Poniatowski’s Bull is a smaller and fainter version of the much older Taurus.

The French Academy inexplicably perched the Bull on Ophiuchus’s shoulder in the direction of Aquila, the Eagle. By the 19th century, the memory of the noble king had faded — and so had the constellation. Astronomers returned its stars to Ophiuchus.

In both ancient and modern times, stargazers identify Ophiuchus with Asclepius, the Greek god of medicine. The old 17th century star maps depict him holding a long staff, which came in pretty handy, as we shall see.

Asclepius was the son of the sun god Apollo and the mortal woman Coronis.

Apollo spent the daylight hours riding in the golden chariot that carried the sun across the sky. Since he had a chauffeur (the chariot-driver Helios), Apollo had plenty of time to gaze down on Earth.

One day, he spied Coronis, and it was lust at first sight. Like all the gods, Apollo had no scruples about sleeping around with mortals, but he was still the jealous type. Coronis dared to two-time him with a mortal man while she was pregnant with Apollo’s child.

In a fit of rage, he shot Coronis with an arrow and killed her. As the flames of her funeral pyre rose around her, he plucked his unborn child from his mother’s womb just in the nick of time.

Apollo was not exactly the maternal type. Instead, he foisted his son on Chiron, a centaur, who had the lower body of a horse and the upper body of a human. The centaurs were skilled in hunting and healing the sick, so Asclepius soon excelled in the medical arts.

Sadly, such gifts can be both a blessing and a curse. One day, King Minos of Crete kidnapped the unfortunate physician. The king’s son, Glaucus, had fallen headfirst into a vat of honey and drowned.

Minos ordered Asclepius to bring the boy back to life.

Glaucus was clearly beyond help, but Minos was not the type to take “no” for an answer. He had the Minotaur, a voracious killing machine with a bull’s head and a human body, to enforce his often unreasonable wishes.

If you didn’t do what Minos wanted, he sacrificed you to the very hungry Minotaur. As Yoda might say, “Torn apart and eaten you were.”

As the good doctor sat, staff in hand, contemplating the cold (and sticky) body of Glaucus and his impending dismemberment, a snake slithered up his staff. In alarm, Asclepius slammed the staff to the ground again and again until the snake was dead.

The physician was amazed to see a second snake creep up to its dead companion a moment later. In its mouth was some sort of herb, which it placed in the dead serpent’s mouth.

The dead snake immediately returned to life. Asclepius snatched up a bit of the herb and gave it to Glaucus, who sprang up as if he had never been dead at all.

The physician had thus found the secret to conquering death. So successful was he that the flow of souls to the Underworld, where the dead were supposed to reside, diminished significantly.

Hades, the dark lord of the Underworld, was not pleased. He stormed up to the CEO of the gods, the mighty Zeus, and complained that Asclepius was cutting into his business.

Zeus knew that Asclepius had thrown into turmoil the natural order of the universe, so he zapped him with a thunderbolt. The greatest healer the world had ever known died a horrible, ironic death.

In tribute to his great skill as a healer (and to assuage the anger of the mighty Apollo), Zeus placed Asclepius in the sky as the constellation Ophiuchus. Around his waist can still be found the serpent. In part, the snake represents the way Asclepius had learned of the healing herb, but its meaning is far deeper than that.

To this very day, in some physicians’ offices, you will see the caduceus, the staff of Asclepius. Intertwined upon the staff are two serpents to symbolize the constant struggle against death with which every physician must contend.

Scientifically speaking, Ophiuchus gets its fame from its two most famous denizens, one of which was only briefly but spectacularly visible.

In 1604, a new star blazed unexpectedly in the southern part of Ophiuchus. The star briefly exceeded the brightness of the planet Jupiter and was visible to the unaided eye from October until March. Such exploding stars, called supernovas, can briefly attain 100 million times the brightness of our relatively puny sun.

Jan Brunoski, a student of astronomer Johannes Kepler, first spied the new star. Kepler observed Kepler’s Star, as it came to be known, until it faded from naked-eye visibility.

Since the Greek philosopher Aristotle, people had believed that the heavens were perfect, unchanging, and “incorruptible.” Brunoski’s and Kepler’s discovery of a new star was paradigm-shattering news.

Today, astronomers understand that supernovas represent the end of a very massive star’s short life. They must content themselves with studying their brief presence in distant galaxies because none has been seen in our Milky Way since that fateful day in 1604.

Ophiuchus is also privileged to contain Barnard’s Star, also known as Barnard’s Runaway Star.

At a mere six light-years away, Barnard’s Star is the second-closest star after the Alpha Centauri system to our sun and Earth. One light-year is equal to 5.9 trillion miles. “Close” is a relative thing when you’re talking about astronomical distances.

As a “red dwarf” star, Barnard’s Star is exceedingly tiny at only 16 percent of the sun’s mass. Consequently, it converts its hydrogen to helium much more slowly and produces far less energy — only .0004 of our sun’s luminosity.

If you happen to be a star, there are real advantages to living in the slow lane. Red dwarfs like Barnard’s Star are among the most long-lived stars in the universe.

The sun will live perhaps 11 billion years. Barnard’s Star may still be percolating along after a trillion years.

In 1916, American astronomer E. E. Barnard discovered that the star was moving extraordinarily quickly through the galaxy. It is moving in our general direction at a zippy 87 miles per second.

In about 8,000 years, it will approach its closest point to us. At four light-years away, it will then be the nearest star to the Earth and sun.

The two stars provide an instructive contrast in stellar lifestyles. Should we live a quiet, stable life like Barnard’s Star? Should we live a long time but leave no mark on the universe? Or should we, like Kepler’s Star, live fast, die young, and leave a beautiful supernova?

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By Tom Burns

Stargazing

Tom Burns is the former director of the Perkins Observatory in Delaware.

Tom Burns is the former director of the Perkins Observatory in Delaware.