An old chart depicting Taurus the Bull

The constellations we recognise today have seen many changes over the millennia of human history.  Some have their origins well and truly lost in the mists of time and some are recent in our history.  This month we will take a look at how they came to be known as they are today. 

Which constellation is the oldest? No one really knows but some are very old indeed.  Ursa Major is thought to be one of the oldest of all, with it's roots reaching back to when the Ice Ages gripped the earth.   The constellation is known to the native peoples of both Siberia and Alaska, suggesting that the Great Bear was recognised before the ice melted and broke the land bridge between the two continents, creating the Baring Straight. 

The ancient Egyptians had their own constellations that may have dated back to end of the last Ice Age as well.   Their name for the bright star Vega was "The Vulture Star", referring to when it was last the northern pole star 14,000 years ago. 

The ancient Babylonians (circa 5600 B.C.) created some constellations but they also used some that had been  made before.   As they kept accurate and detailed records of celestial events they were one of the first peoples to realise how to predict solar eclipses, to trace the path of the sun through the stars (what we call the ecliptic) and they may have created the first of what we call the Zodiac; We know these as Sagittarius, Pisces, Gemini and Virgo. 

While a lot of the constellations we now use are associated with Greek mythology, the ancient Greeks did not invent the shape of the constellations, but added their own stories to the constellations that already existed.  Aratos, in 270 B.C. listed 42 constellations that he knew and were already established.  Ptolemy listed 48 constellations in the 2nd Century A.D.  which he was summarising from previous works, including the first man to accurately chart  the stars, Hipparchus (circa 150 B.C.).

The Chinese independently developed their own detailed constellations but they were not recognised by the Western world.  They recorded their observations very accurately though and those records can still be used today to pin-point the location of past supernovas, comets and other celestial events.

A woodcut print of the northern sky, 16th century
From The Complete Woodcuts of Albrecht Durer, 1515 
© 2000 

The constellations of the southern sky were not added until the Europeans began sailing far across the globe and the sailors found an unfamiliar sky.  Johann Bayer (1572-1625) was the next person to considerably add to the number of constellations.  He added 12 in all, including  Musca the fly, Dorado the Golden Fish, Pisces Volans the Flying Fish and Chameleon.  Johannes Hevelius (1611-1687) added a few more, including Leo Minor the Lesser Lion and Lynx.  The last group of new constellations was created by Nicholas Louis de Lacaille (1713-1763) and  two Dutch navigators Peitr Dirksz Keyser and Frederick de Houtman.  Lacaille named most of his constellations after new and important scientific apparatus of his time.  From him we gained a number of small faint constellations such as Fornax the Furnace, Antlia the Air Pump, Horologium the Pendulum Clock and Microscopium the Microscope. 

The constellations did not have fixed boundaries either,  The ancient Greeks only considered those stars that formed the pattern of the constellation to be part of it.  The first printed charts which appeared in the 16th century had no boundaries marked as they were meant as a guide to the naked-eye stars.  Eventually uranographers (those who charted the stars) began roughly drawing in boundaries as it suited them and no two matched exactly.

By the end of the 19th century it was all starting to get a bit messy and it would be easier if everyone used the same constellations that had the same boundaries.  So in the 1920's the newly formed International Astronomical Union charged frenchman Eugene Delaporte with the task of creating a uniform sky for astronomers to use.  The 88 constellations we now use were presented by Delaporte in 1930.  This is why the astrologer's Zodiac does not match the modern sky.  Astrologers assign exactly 30 degrees of the ecliptic to each representative constellation/sign.  To an astronomer the Zodiac has no meaning other than an interesting piece of history that helped ancient civilisations keep track of the seasons, as the sun clearly travels through more than 12 "modern" constellations on it's yearly journey.

The southern sky, as it was then known.
From The Complete Woodcuts of Albrecht Durer, 1515 
© 2000 

Some constellations that didn't survive or fell out of favour include Felis the Cat, Le Renne the Reindeer, Globus Aerostaticus the hot-air balloon (a tribute to the Montogolfier Brothers), Cerberus the Three-headed Dog, Robur Carolinum the Oak of Charles (this one was added by Edmund Halley in an effort to curry the Royal favour) and Triangulum minus.  Vulpecula and Anser, the Fox and Goose, was shortened to Vulpecula.  Antinous, a constellation mentioned by Ptolemy, was incorporated into Aquila the Eagle.  Cor Caroli, the Heart of Charles, was a one star constellation created by the physician to King Charles II to honour Charles I.  It is now recognised as the brightest star in Canes Venatici the Hunting Dogs.  Malus the Mast was created by Lacaille when he split up Argo Navis but it has now become part of Pyxis the Compass.  Scorpius once had long claws that are now part of Libra but we are reminded of this by the proper names of the stars, Zubenelgenubi the Southern Claw and Zubeneschamali the Northern Claw.  The Pleiades were once considered a constellation on their own but now reside inside the boundaries of Taurus.

This article is ©2000 Stargazers Astronomy

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