When you look up at the night sky, what do you see?

Maybe it looks like a random smattering of dim lights.

Or perhaps you see in the stars the shapes that can predict your future.

If you’re a nerd like me, then you see a field of data and numbers that reflect the quantitative reality of our universe.

To our distant ancestors, unimpeded access to the celestial sphere was almost like a god-given right.

In fact, when many of them gazed at the stars — and the dark spots in between — they did see messages left for them by their gods.

What exactly were those messages and how have our interpretations of them changed over time?

When I decided to study both astrophysics and mythology in college, everyone assumed I would be focusing on astrology or constellation myths.

Well, joke’s on them because I can still only reliably identify a single constellation — *shout out to Orion* — but along the way, I have developed a real appreciation for the role that constellations and their myths play in adding to our understanding of the physical universe.

Before we had GPS, weather balloons, and smartphones, humans relied on constellations to keep track of time, predict weather, preserve culture, and navigate as they spread around the globe.

They also used the stars to foretell the future and commune with their gods, which seemed much more reasonable at a time before humans discovered physics.

This practical and religious knowledge was encoded in myths.

The Ojibwe people native to the Great Lakes region in the US tell a myth about the Fisher constellation.

Long ago, the world was covered in snow and ice, and there were no birds to announce the coming of spring.

The Fisher was a great hunter, who went up to skyland to free the birds and bring warmth back to the Earth.

When the sky people caught Fisher freeing the birds, they started to chase him, but he escaped to the sky, where he was trapped forever by an arrow through his tail.

This Ojibwe myth serves multiple purposes.

It explains the changing of the seasons, and the constellation it’s attached to acts as a reminder of spring’s return.

No matter what they used the constellations for, the fact that ancient humans used them at all meant that people were studying the sky.

The brightest minds around the world took meticulous notes about how the sky changed over time, and without those early astrologers, the field of astrophysics as we know it would be drastically behind.

I would probably lose my astronomer’s card if I didn’t tell you this at some point, so here goes.

Our planet is just one of many orbiting a star, which is just one of billions orbiting a galaxy, which is itself also just one of billions in the vast universe.

The points of light that we see in the sky are distant stars, and despite what the myths may tell us, their arrangement is nothing more than a coincidence.

Based on early written records and physical artifacts, most historians agree that ancient Mesopotamians were among the first to observe the motion of stars in the sky and assign divine meaning to it.

Because the sky was believed to be the home of many gods, the shifting shapes in the inky darkness were interpreted as omens.

Like an omnipotent teacher scribbling on the blackest of boards.

Babylonian sky watchers in the 18th century BCE were especially prolific in their study of the heavens.

The Babylonians and their neighboring Assyrians also gave us many of the constellations we use in the West today, like the Crab, the Bull, and the Twins.

These days, we call them Cancer, Taurus, and Gemini.

Ancient Mesopotamians even invented the zodiac, the sequence of 12 or 13 constellations that the sun appears to “pass through” over the course of a year, though the sequence’s name and its association with horoscopes were added by the Greeks almost 2 millennia later.

Originally, the zodiac was used as a way to keep track of time.

The Mesopotamian constellation myths trickled into Egypt over a few hundred years after it was conquered by Persia and then Alexander the Great in the 6th and 4th centuries BCE.

These new myths merged easily with the Egyptians existing beliefs, because they had already been using the patterns of the night sky to keep track of time for practical reasons, most of them having to do with farming.

When Sirius, the brightest star in the sky appeared over the horizon, ancient Egyptians knew that it was almost time for the Nile River to have its annual flood, which would nourish the soil for next year’s crops.

The constellation mythology spread to Greece by the 3rd century BCE, where they were called “katasterismoi,” meaning “placing of the stars” because they believed the constellations were put in the sky purposefully by the gods to teach them lessons.

The Greeks’ religious fervor combined with their taste for numbers produced astronomy: the meticulous and mathematical observation of the sky… so that we can know exactly how the gods want us to live our lives.

Unfortunately Greek astronomers like Ptolemy spent all that effort describing a system that relied on a fundamentally flawed assumption: they believed the Earth was the center of the universe.

That belief held as both astrology and astronomy made their way through the Islamic world and over to Europe, where geocentrism remained popular until the heliocentric revelation in the 1500s.

Nowadays, around 70 million Americans claim to read their horoscope every day, and nearly a third believe that astrology is real or vaguely scientific.

As a scientist, I don’t love those stats, but astrology in western countries is mostly a novelty, an interest that people might use to help them make small decisions.

But different astrologies developed more-or-less independently in China and India, each with their own constellations and interpretations.

Astrology is still popular in some parts of the east.

In China, star charts may be consulted to determine compatibility in love, or to make a big career decision.

In India, astrology is used by many to dictate decisions about medicine, marriage, careers, business deals… often in a harmful, discriminatory way.

I’ve always thought it was kind of a shame that conversations about constellations are so often dominated by the Greeks, because some of the most beautiful views of space can only be seen properly from the southern hemisphere.

You can see the blurry Magellanic clouds and the great dark rift cutting across the stream of the Milky Way.

And because the stars you can see depend on your latitude, you can even see different constellations, like the Southern Cross.

Celestial navigation in the southern hemisphere is inherently more difficult than in the north because there’s no south star that stays put as the rest of the stars appear to twirl around it.

Instead, they have the Crux, a small group of four stars.

Despite this difficulty, Polynesian wayfarers used the southern stars to travel around the Pacific more than 1000 years before Europeans traversed the oceans using their compasses.

In the time of ancient Greece, before Polaris was our north star, the Crux was visible from more northern latitudes.

But the Earth’s axis wobbled, and now the Crux is a quintessentially southern constellation, one featured on several southern countries’ flags like Brazil, Samoa, New Zealand, and Australia.

Some scholars believe that the astronomical record in Australia goes back 65,000 years, but the timing is hotly debated.

The Aboriginal and Torres Strait Islander People are spread between several hundred different language groups with a wide variety of spiritual beliefs and lore.

Despite their many cultural differences, cave paintings and other archeological evidence show that many Aboriginal Australians were using stars as calendars for more than 10,000 years before the Babylonians read their motion as omens.

And in a time before written language was developed, the user manual for these celestial timekeepers was passed down through oral stories and other artforms.

One constellation common to many of the aboriginal tribes was the Emu, whose head was the dark Coalsack nebula nestled next to the Southern Cross.

Re-record One constellation common to many of the aboriginal cultures is the Emu, whose head was the dark Coalsack nebula nestled next to the Southern Cross.

The Emu’s legs stream out behind her, following the path of the milky way.

Some stories say this is because the Emu used to have great wings that it used to fly across the sky.

The Emu constellation’s appearance in the sky coincided with egg-laying season for the more earth-bound emus.

Those eggs are an important source of nutrients for the aboriginal Australians, and so the constellation was a life-saving reminder.

The Pleiades star cluster is known among many groups as the Seven Sisters.

Though the details of the story vary across the continent, the sisters are usually said to be running from something, maybe a hawk or an unwanted suitor.

The Yamaji people in Western Australia used to predict how heavy the seasonal rains would be based on how bright or faded the Sisters looked in the sky.

To some aboriginal cultures, the stars in the Western constellation Orion form a canoe.

According to the Yolngu people in the Miwatj region of north-eastern Australia, the three stars that make up Orion’s belt represent three brothers fishing in the canoe.

When one of them got hungry enough to break the law by eating a sacred fish, Walu the Sun-woman lifted them to the sky in punishment.

So ancient humans all over the world used the sky to learn and teach traditions, to navigate and keep time.

Unfortunately, so many people today are prevented from connecting to the stars in the same way our ancestors did.

According to the Dark Sky Association, a nonprofit dedicated to ensuring everyone has access to the night sky, about 80% of the world population has a diminished view of the sky because of light and air pollution.But losing access to the stars doesn’t have to be an inevitable casualty of scientific progress.

Through policy and individual action, we can reduce atmospheric pollution of all kinds and have more of a say in what we see when we look up.

Maybe one day I’ll even be able to see more than just a handful of stars from my NYC apartment.

A girl can dream, can’t she?

In the meantime, there are plenty of apps you can use to acquaint yourself with the night sky and track constellations as they spin above you, even if you can’t see them.

Just knowing they’re there will connect you to all the humans who have contemplated the stars before you.