The History of the “Galaxy,” from Chaucer to the Clash with Andromeda
The meaning of the word “galaxy” changed through the centuries, as did our understanding of the Universe
We are never really sure when a word entered a language. We may find it in an ancient text, but it was probably already used in conversation — and we can never be really sure if someone won’t find another older manuscript with the same word. In the case of “galaxy,” as far as we know, the first time it appeared in writing in English was in House of Fame, a poem by Chaucer. Here it is, in all its Middle English glory:
See yonder, lo, the Galaxyë
Which men clepeth the Milky Wey,
For hit is whyt.
The verses seem easy to translate into modern English: “See there, the Galaxy, which men call the Milky Way, for it is white.” But this apparent translatability of the word hides a wide gap between the word in Chaucer’s time and our own. This gap tells us a lot about our knowledge of the Universe.
When writing about the Galaxy—which men call Milky Way — Chaucer is talking about, well, the Milky Way, which we can hardly see in our cities. In a field, far from lights, we can still see it.
The Milky Way has various names around the world: It is the Silver River, as the Chinese call it, or the Skirt of Stars, in the mouths of the Aztecs, or the Path of Birds, in Finnish — or it is the Way of St. James, as the pilgrims said, for whom this streak in the sky served as a nocturnal guide.
The Greeks and Romans looked up at the sky and saw spilled milk — the Greek word it’s derived from, γαλα (gala) means “milk.” Little did they know that the secrets of the beginning of everything were hidden in that streak.
With the naked eye, we cannot perceive what that streak of light is made of. It is this mystery, this ignorance, that lies behind Chaucer’s words. That Galaxyë is not the galaxy we find in school books. It is a streak in the sky that we can’t explain.
Like a clue to solve a crime, our curiosity about these streaks in the night sky over the centuries reveals secrets about the past and future of the Galaxy — but in Chaucer’s time, not much more was known than this: There is a huge, white streak in the night sky. We are on Earth, at the center of the Universe, and up above there are stars — and that streak.
With increasingly powerful lenses, we came to understand that the Milky Way is light from a group of so many distant stars that we cannot distinguish them. We also began to understand that Earth is not the center of the Universe.
Over time, some studied the shape of that cloud of stars and — in a surprising twist — we eventually concluded that we are part of the Milky Way! Neither Earth nor the Sun are the center of the Universe: The entire Solar System revolves around the Galaxy. When we look at the Milky Way, we look at the center of the galaxy.
We thought we had found the shape of the Universe: a dense heart of stars, with arms of stars around it (in one of them are we), all spinning. But the surprises had not ended…
Telescopes allowed us to see, in the midst of our galaxy, a few distant objects that were neither stars nor clearly identifiable. A Frenchman, named Charles Messier, cataloged these intriguing objects. He called them nebulae. They were yet another clue inscribed in the sky.
One of these nebulae was actually known to ancient astronomers because it can be seen with the naked eye — it’s located in the Andromeda Constellation and was cataloged as M31. Little did Messier know that this particular patch — the Andromeda Nebula — would give rise to one of the greatest surprises in the history of astronomy.
Some had already suspected. Immanuel Kant proposed the idea that these patches in the sky could be other galaxies. The idea was as strange at the time as suggesting today that there are other universes — some people do propose this, but, now as then, we are dealing with pure speculation.
In the 1920s (not even 100 years ago), Edwin Hubble finally managed to measure the distance separating us from the Andromeda Nebula. He calculated it at approximately 900,000 light-years. In short, it is extremely far — significantly farther than the center of our own Galaxy. In fact, Hubble made a mistake: Andromeda is more than 2.5 million light-years away. When we look at that patch, we are not seeing a nebula within our galaxy: we are looking at another galaxy.
From that point on, with telescopes improving every day (the most famous one even bears Hubble’s name), we realized that there are millions upon millions of galaxies — Andromeda and the Milky Way (which ceased to be synonymous with “galaxy” and became the proper name of our galaxy) are just two among many.
The Universe seems to be made of strands of galaxies, and these are made of stars, planets, and other materials.
We still have two twists to reveal in the story of the Milky Way and company.
By observing galaxies using increasingly powerful telescopes, astronomers noticed that all of them had a redshift in their luminosity. Why? Because they are moving away from us in all directions — just as an ambulance sounds lower-pitched as it moves away, a gigantic object appears redder, which can only be detected with advanced equipment.
If galaxies are moving away, it means they were once closer together. By making calculations — and what calculations they were! — astronomers deduced that 13.8 billion years ago, all galaxies were in the same place. It was at that moment that everything began (and it hasn’t ended yet). The Big Bang theory emerged, which explained the history of the Universe (except for the exact initial moment, which still eludes all calculations). In the 1960s, the cosmic microwave background radiation left by the Big Bang was discovered, a radiation that the calculations of those who developed the Big Bang theory had already predicted.
The Big Bang became the most rigorous scientific explanation for the history of the Universe — it doesn’t explain everything, but it matches the data we have.
Of course, there is still much to learn — for example, what is dark matter made of, which calculations predict, but cannot be seen? Without it, many of the galaxies we observe couldn’t exist, as the gravity of stars is not enough to hold them together. It’s not hard to see in it the reflection of the mystery of that whitish patch in Chaucer’s sky: What will future generations say when they think of us and the honest name of Dark Matter? Will they give it another name?
The very term Universe: will it cease to mean everything that exists, just as Galaxy once did, and come to signify one of several universes within a multiverse?
Now, the last twist. The Andromeda Galaxy — the galaxy that was key to discovering all the others and realizing that our galaxy is not alone — does not exhibit the redshift deviation. It is not moving away. Its light, in fact, has a slight shift towards blue. It is approaching, just as is the case with a handful of nearby galaxies.
In other words, in a good many million years (many millions!), the Milky Way and Andromeda — with its approximately 12 trillion stars — will collide, merging into a single galaxy. None of us will be around to see it, but when it happens, it will be as if even more milk were spilled across our skies. At least it won’t be a surprise. That smudge in the Andromeda constellation will grow ever larger.
We began with Chaucer and ended in the future, with an intergalactic collision. Human beings live in this space between the unknown expanse and our perception of it, reflected in the words with which we fill our days.
While we await the collision, I have two suggestions.
The first suggestion is to read a book about this entire story: Until the End of Time (Penguin, 2020), by Brian Greene.
Second: If you are in a city one of these days, take yourself and travel a good few miles to the darkness of the countryside. Gaze upon the Milky Way and, with the help of one of the many apps available on smartphones, also look for the Andromeda Galaxy. The light that will enter your eyes left Andromeda 2.5 million years ago when the humans who existed then looked at the starry night and scratched their heads. They may have already had the flashes of curiosity that led us to invent telescopes and perform calculations upon calculations to understand what those smudges in the sky actually were. This curiosity has already given us quite a few surprises — I cannot even imagine those that are yet to come…
