Mapping the Stars: A Brief History of the Constellations

The awe of looking up at a dark, clear night sky is a pretty universal human reaction. When faced with the magnitude of the heavens above us, it’s only natural to feel humbled. But given enough time, the raw edge of amazement starts to wear away and humans staring at the sky will do what humans do—we make patterns.

The creation of constellations is something we see in cultures from around the world. Even if a given culture didn’t fill the sky edge to edge with shapes, it was hardly uncommon for any particular group of people to create at least a few key sky patterns.

Given that, where did the 88 official constellations we use today come from? The temptation is just to say “Greece and Rome”, but that’s really only a piece of the story. So let’s dive a little into the history of our modern “official” constellations.

Oh, Those Greeks

Okay, but yes, we are also going to be talking about Greece and Rome, though again I want to be very clear that they were not the only ones doing this nor were they necessarily the earliest. There is certainly evidence scattered around the world to support the idea that very ancient humans were tracking the sky, and there is also plenty of evidence to suggest that folks from Babylon to China were writing down star catalogs.

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All that said, the catalog often credited as the oldest one for which we have definitive evidence is that of Hipparchus. Hipparchus was a Greek polymath who, when he wasn’t inventing trigonometry, created a catalog thought to have contained careful measurement of the positions of at least 850 stars. This was all going down sometime in the decades around 150 BCE.

Calling this one the oldest catalog is also kind of stretching it. For one thing, we have surviving writings of Hipparchus commenting on a commentary of an older work of astronomy from Eudoxus of Cnidus from something like 350 BCE which may have included a limited star catalog. For another, Hipparchus’s catalog is gone. No surviving copies of it have ever been found.

That said, we know a lot about it because a few centuries after Hipparchus’s time, the Greco-Roman astronomer Claudius Ptolemy used it as the basis for his work and subsequently preserved a lot of details of its contents.

Talkin’ Ptolemy

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If you’ve ever heard of the Ptolemaic model of the universe, the geocentric version with Earth in the middle of everything that dominated humanity’s idea of the cosmos for centuries, it’s named after this guy. Partially this was because it appealed to certain religious factions’ view of how they’d like things to be, and partially it’s because his greatest astronomical treatise, Almagest, has survived to the modern day.

Almagest includes a star catalog that used Hipparchus’s (amongst possible other sources) as its basis, though it expanded the entries to over 1,000 stars. His book also included a list of all the constellations that could be seen from Alexandria, in Egypt, which is where Ptolemy would eventually die sometime around 170 CE.

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That constellation list contained 48 constellations, 47 of which are among the 88 official constellations we use today (though his versions of Leo and Centaurus would eventually have pieces lopped off of them to form other constellations). The exception is the constellation Argo Navis, the mythical ship Argo…and even that one is kind of still around (I’ll explain later). 

So a big ol’ chunk of our modern constellations are simply drawn from the ones Ptolemy knew. Where he got them is another question, but he was the go-to astronomical reference source for Western astronomy basically until the Enlightenment. The man may have been wrong about some things, but he casts an enormous shadow in astronomy science history.

More Patterns

It wasn’t until over a thousand years after Ptolemy’s death that folks would start to think of new constellations that would stick around to become official (I’m sure people were making up new shapes all the time, but most of those are lost to history). The earliest new constellation that is still in use today was actually around in Ptolemy’s time, it just wasn’t one of his official constellations.

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This is Coma Berenices, Berenice’s Hair, the only constellation to be named after a real person. That person is Berenice II, queen of Egypt, who sacrificed her long hair in thanks for her husband’s safe return from battle. Coma Berenices as a pattern was known in ancient times, but Ptolemy made it part of Leo. It wasn’t until the 1530s when a German cartographer published a sky chart showing it as a separate constellation that it became well known as its own shape.

Once the Age of Exploration began and European scholars started to get better looks at Southern Hemisphere skies invisible to their homelands (and to Ptolemy), suddenly a whole raft of new constellations appeared. Of the ones that survive today, Dutch cartographer Petrus Plancius is responsible for four of them. Well, three and a half. He is, as far as we know, the first to create the shapes Columba, Monoceros, and Camelopardalis, and he is also the one credited as being the first, in 1589, to lop off a piece of Ptolemy’s version of Centaurus to create the Southern Cross.

A Dutch fleet returning from Sumatra in 1597 carried with them star charts that included twelve new Southern star patterns, mostly named for wildlife. The first star atlas incorporating the entire sky above Earth, northern and southern, was 1603’s Uranometria.

Filling in the Gaps

At this point all of the constellations that we know today that use up the bright stars of Earth’s sky were in existence, 64 of them. But of course, there are 88 constellations today. Most of the remaining ones came from folks trying to fill in the gaps between the bright constellations with patterns that use all those fiddly faint stars that were not traditionally of use to most folks.

First up was Johannes Hevelius from modern-day Poland who clearly didn’t like that these gaps existed. He came up with ten constellations to fill in the spaces left in the northern hemisphere sky in 1687. Of his ten, seven are still in use. Even after all my years doing star shows in the Planetarium, if you ask me to find any of those seven in the sky the best I’d be able to do is to gesture vaguely at the spots they’re supposed to be in. 

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That, of course, still leaves us with 17 missing constellations, and credit for those goes to French astronomer Nicolas-Louis de Lacaille. After mapping the skies from South Africa, in 1763 he published a star catalog containing 14 new constellations as well as one old one he subdivided. Not gonna lie, his new constellations have the worst names. He was trying to honor the Age of Enlightenment, but naming constellations for furnaces and air pumps is so…unpoetic.

Lacaille’s final contribution was to chop Ptolemy’s Argo Navis into pieces. In his defense, as a single constellation Argo Navis is super freakin’ huge and takes up an absurd percentage of the sky. Lacaille was the first to suggest hacking it into ship bits: Carina (the Keel), Puppis (the Poop Deck), and Vela (the Sail), making each individual pattern much less unwieldy.

Enter the Namekeepers

If you read last week’s post you know that the International Astronomical Union is the be-all and end-all when it comes to giving space things official names. They didn’t exist until 1922 but cementing the official set of constellations was the first thing they did, drawing from Ptolemy and the European scholars who followed him to pin down the 88 patterns recognized today as the official set of constellations.

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Of course, as I hope I have made clear, that’s not the only set. It’s convenient to have a single agreed-upon set to use as references points in the sky for scientific operations, but looking up at the sky has never been a purely scientific endeavor. It is, first and foremost, a terrifically humanistic one.

So while I hope you’ve found this history of modern official constellations informative, I also hope that when you gaze up at, say, Ursa Major, the Great Bear of Greek mythology, you also enjoy the Big Dipper, the Boat, the Wagon, the Plow, the Crocodile, the Caribou, or the Fisher Cat—all names given to at least part of that constellation by different cultures around the world.

Or make up your own constellations! After all, picking out patterns is something our human brains like to do. Follow in the footsteps of your ancestors and see what shapes you can find. The beauty of the stars is that they belong to all of us, and each of us can find ourselves within them.