Curious Constellations

Wait a minute!  Why is the Sun found in Ophiuchus at all?  Is THAT a constellation of the Zodiac?  We don’t see horoscopes for Ophiuchus as a Birth Sign!

What’s the explanation? 

In fact, the large summer constellation of Ophiuchus (the Snake Handler) has been recognized in the sky for thousands of years.  Ophiuchus appears as a large, slightly narrow pentagon of stars and traditionally carries a long snake wrapped around his body.  The starry snake, which is separated into two parts by being partly behind Ophiuchus’ body, forms the constellation of SERPENS (that’s another story!).

You see, originally the constellations were simply groupings of stars which traced out cartoon-like outlines (stick figures) of familiar objects in the sky.  Often, the edges and other features of these figures were represented by individual stars.  Many ancient cultures knew the year is 12 months long, so they similarly divided up the great circle of the Sun’s path (“Ecliptic”) through the stars into 12 groups of stars.  That resulted in one star grouping for each month, and the collection of all 12 groups of stars became known as the 12 Constellations of the Zodiac.  Traditionally, each of these 12 Constellations “ruled” an exact one-twelfth of the Zodiac. 

But!  Even a casual look at the Zodiac in the night sky will show the star groups are not of equal size.  Nor are they equally spaced along the Ecliptic.  In some places there are much larger “blank spaces” between recognizable star patterns.  However, in the interest of uniformity, the ancients divided the Zodiac into 12 EQUAL divisions in Celestial Longitude around the Celestial Sphere.  Also, while the ancients noted that the Sun actually never traveled directly through the body of SCORPIO the Scorpion, that pattern of stars is TOO SIMILAR to that of a real scorpion to be ignored!  So, Scorpio has been featured in all the ancient Zodiac star groups.

The years between 1640 and 1860 marked the heyday of visual telescopic astronomy.  In early sky maps, areas of the sky with only faint stars simply became gaps between the more recognizable constellations.  Later, maps and atlases were published showing different boundaries, spellings and even names for familiar constellations.  New constellations began to be invented as the Southern Hemisphere was explored.  Soon, “empty” regions in the sky were filled with constellations honoring kings, “modern science” and even ordinary objects. (This is how MICROSCOPIUM & TELESCOPIUM [honoring the microscope and the telescope] came into existence.  Similarly, arose MUSCA (the fly), TUCANA (the Toucan), HOROLOGIUM (the clock), and several other constellations most of us will NEVER recognize!

Astronomers, though, continued to happily study the stars, and began to map “their” skies using Celestial Longitude (“Right Ascension”) and Celestial Latitude (“Declination”).  For the most part, astronomers became indifferent as to the actual boundaries of the constellations.  In about 1860, astronomers began to use the new science of photography to record the skies. 

However, as astronomers amassed large databases (e.g., of Double Stars, Nebulas, Variable Stars, etc.), it became apparent that new systems were needed for naming objects and locating them in the sky.  On the one hand, objects identified only by Celestial Longitude (Right Ascension) and Celestial Latitude (Declination) were quite unwieldy (and rather unfriendly!).  On the other hand, constellation names, locations and even star populations were becoming increasingly in doubt.

Several attempts to standardize the positions and boundaries of the constellations occurred in the 1800s.  These sparked much debate inside the astronomical community and between astronomers and laymen.  (Note today that efforts to change Congressional Districts or city/county boundaries are also very controversial!).  Finally, in 1928 the International Astronomical Union, or IAU, formall voted and agreed to a permanent set of constellation boundaries.  The new maps took effect in 1930.  Today:

1) EVERY part of the sky formally belongs to one and only one Constellation
2) Constellation Boundaries lie ONLY along lines of Right Ascension and Declination

The most controversial change “redistricted” SCORPIO into a smaller “box” in the sky, and adding OPHIUCHUS to the list of constellations crossed by the Sun during the year.  So, beginning in 1930, Ophiuchus was recognized as the 13th Constellation of the Zodiac.  Perhaps persons born between November 30th and December 18th should now recognize Ophiuchus as their “sign”?