Ophiuchus, the Forgotten Sign of the Zodiac

Screenshot 2016-04-24 13.25.46
Early morning view to the south 3 hours after midnight, tomorrow with the waning gibbous moon, Saturn and Mars in Ophiuchus, north of the red supergiant star Antares, the heart of Scorpius, the scorpion. Note the ecliptic passing through Ophiuchus and the proximity of the moon, Mars and Saturn to the ecliptic. Also note the brightest star in the constellation, α Ophiuchi or Ras Alhague, often condensed to Rasalhague at the northern-most point of the constellation. Click the image for full-res view.

Since the summer is almost upon us and, with it, all the favorite constellations of summer such as Sagittarius and Scorpius, this would be a good opportunity to point out and discuss the often forgotten 13th constellation of the Zodiac, Ophiuchus.

In classic astronomy (and astrology), the Zodiac is the circle of 12 30º sections of celestial longitude centered on the ecliptic and extending 9º to its north and south. It is represented as the imaginary path on the sky for all solar system objects as they move in their orbits, planets in their orbits around the sun or moons of the planets in orbit around their host planets. The motions of all solar system objects are aligned with this imaginary path on the sky.

By definition, Zodiacal constellations, 13 in total, are located along this path of the Zodiac or, more accurately, the path of the ecliptic. Since the sun is the principal mass in our solar system, the path of the ecliptic is defined by the sun’s apparent path on the sky  as it appears to “move” across the sky, rising in the east and setting in the west. As we all know, this diurnal motion, the rising and setting of all objects, is an aspect of the earth’s 24 hour rotation.

In Greek mythology, Ophiuchus is known as the serpent bearer and represents the Greek god of medicine, Asclepius. It is one of 13 constellations through which the ecliptic passes and, as such, it is a constellation of the Zodiac, a “13th” sign, if you will.  As the serpent bearer, Ophiuchus holds Serpens Caput in his left hand, and Serpens Cauda in his right hand and is located south of Hercules and north of Scorpius, between Libra and Sagittarius. It should be noted that, to this day, Asclepius and the serpents  are snakes(invert)associated with  healing, entwined around the staff of Asclepius. It should be further noted that all physicians take the Hippocratic oath, promising to follow in the path of Hippocrates, the healer who, according to Greco mythology, is a descendant of Aesculapius (Latin).

So why isn’t Ophiuchus included in your “Horoscope”, as a possible “Birth Sign” or as a constellation of the Zodiac?

This is a question that has been hotly debated as of late, most notably in a series of  articles dating back to January, 2011. Parke Kunkle, Ph.D, a professional astronomer and professor of same at Minneapolis Community and Technical College, Minneapolis, Minnesota, stirred up a hornet’s nest of controversy by suggesting that there is, in fact, a 13th sign of the zodiac and that astrologers have gotten it all wrong. Dr. Kunkle is correct and there is a 13th sign of the zodiac and its name is Ophiuchus. So why the controversy and why the omission? Your “birthsign” corresponds to the constellation the sun was in on the date of your birth. To the universal horror of the Astrological community, Dr Kunkle had provided an “alternative” list, based on the real (astronomical) location of the sun on the day you were born; you can discover your own, astronomical “birth sign” using Stellarium.

A Professional Astrologer (yes there are “professional” astrologers, with the term “professional” strictly used to indicate receipt of fees for services rendered) is an individual who gets paid to provide you with a chart, supposedly to guide you on your daily path through life, much as a psychic does.

Before the advent of modern science and the ascent of reason over superstition, many natural phenomenon were explained using prevailing mythologies and existing creation stories. Since nature abhors a vacuum and, in the absence of authentic science, without the light of reason for guidance, the result is the same, superstition and pseudoscience become reality. Today’s uninformed “Truther” movement, with its plethora of experts (an “expert” here facetiously refers to anyone with an internet connection and a website) is a manifestation of this phenomenon, most notably with the rise of the “Flat Earth Movement” and other nihilistic ideas. With the brilliance of the Greeks beginning to spread and as the light of reason began to shine in the darkness, so too began astronomy, the oldest of the sciences, springing from astrology, superstition and mythology to become the mature, modern science it is today. Much of the mythological underpinnings of astrology remain, however, such as the mapping out of the northern and southern skies into 88 distinct constellations, the Zodiac and its 13 constellations and so forth.

Back to our original question; the reason Ophiuchus was not included with “the original 12” is probably linked to the superstitious aversion to the number 13, and definitely to the fact that a 13th constellation would skew the even, 30º sections of sky so neatly setup by the Greeks.  It should be noted here that these even 30º sections of sky also meant that the sun would spend 30 days or 1 month in each of the 12 constellations of the Zodiac. In addition, the 360/12 issue notwithstanding, Ophiuchus shares fame with Imhotep, a real person of Egypt (not Greece) who lived 4700 years ago and, most importantly, because the sun would spend only 19 days out of the year in Ophiuchus compared to 30 days for the other constellations.

NGC6426_07262009
NGC-6426 in Ophiuchus as imaged by the author with a 0.61 meter (24″) telescope in 2009. Click the image for hi-res view.

Ophiuchus, from a purely astronomical standpoint, is one of the largest constellations and is visible during evening hours from late May through November. For early risers, you can see it prominently placed high above the southern horizon sooner in the year, north of Scorpius, between Libra and Sagittarius. Its brightest star, α Ophiuchi or Ras Alhague, often condensed to Rasalhague, is a 2nd magnitude binary star located at the northern-most point of the constellation. Ophiuchus contains many beautiful star clusters, both galactic (open) clusters and globular clusters. Galactic clusters are generally loose agglomerations of young stars found in the plane of our galaxy, forming out of the rich gas and dust of the Interstellar Medium located in galactic disk’s spiral arms. Globular clusters are external to the galaxy (and any galaxy) in what is known as the Galactic Halo, a region around any galaxy’s nucleus that contains these objects, tight agglomerations of some of the oldest stars in the universe. An example of one such globular cluster in Ophiuchus is NGC (New General Catalog) [of non-stellar objects] 6426. NGC-6426 is over 67,200 light years from earth and 46,900 light years from the galactic center which means it’s located on the opposite side of the galaxy in a section of the galactic halo approximately 20,000 light years above the galactic midplane. In terms of its stellar population (as is the case with all globular clusters), it contains some of the oldest stars in the universe and is aged at about 11.5 billion years. Many of its stars have long-ceased producing energy through hydrogen fusion and are now producing energy through helium fusion reactions, having evolved to become red giant and super-giant stars.

Regarding astrology, it has to be noted that the length of the earth’s day and year and the relative placement of the sun and planets to the background stars is a peculiarity local to the earth. If you choose to put credence in astrology, the notion that somehow the position of the planets set against background stars that are light years more distant than they will have an influence on your life and destiny and that you can structure your life accordingly, that is your business but please understand that the Astronomical Zodiac is the only accurate mapping.

Imagination is more important than knowledge 585px-Albert_Einstein_signature_1934(invert)
An index of all articles in this blog can be found here.

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