Stars are in the sky. Constellations are in your head. It’s an old truism. But it may reveal far more about our human nature than we thought possible.
Few things are less compatible than astrology and astronomy.
Unless you throw psychology into the mix.
It turns out they’re part of one of the oldest cognitive science experiments ever.
“We looked at the constellation systems, from cultures all around the world, thinking of these as the outcome of the natural experiment in which people over many, many years in different places around the world have looked at the same stimulus, the night sky and organised it differently into groups,” says Professor Charles Kemp of the University of Melbourne.
It’s about defining the balance of influence between the mechanics of our visual perception and the context our culture imposes upon it.
Our brains are built to identify patterns with minimal input.
It’s a survival trait. Those who “see” leopards lurking in the shadows more often tend to survive longer. The classic demonstration is our ability to see animals in the clouds and a man on the moon.
Things get a bit murkier when it comes to constellations, though.
There are some 5000 stars visible to the naked eye. Then there’s the background glow of the Magellanic clouds and Milky Way.
These present ample opportunity to “connect the dots”.
“Over thousands of years, researchers including anthropologists and astronomers have documented the many different ways in which cultures around the world organise the night sky into systems of stories,” says Professor Kemp.
These efforts have focused on understanding individual cultures and extrapolating historical and cultural links.
One thing has long been apparent.
When it comes to organising the stars into groups, cultures have tended to focus on the same few clusters.
Professor Kemp wanted to know to what extent this was true.
He and his team catalogued asterisms – star groups – from 27 different cultures selected from Asia, Australia, Europe, North and South America and Oceania.
“We found that certain constellations are near-universal, so things like the Pleiades, the Big Dipper and so on, and this was expected from previous research,” he says.
“But we also found there was a long tail of constellations that might not be universal, but appear across many unrelated cultures. So these included things like Corona Borealis, Delphinus, Corona Australis and Corvus.”
But the second part of the discussion focused on why these particular constellations kept grabbing attention.
This used a computational model that grouped stars based on their brightness and proximity in the night sky. The clusters it isolated were the familiar ones.
“So vision scientists sometimes talk about low-level vision, mid-level vision, high-level vision,” Professor Kemp says. “So in our context, low-level vision would be noticing individual stars, mid-level vision would be grouping individual stars together, and high-level vision would be attaching some kind of interpretation to the groups that you see”.
This way, grouping seven stars into the Big Dipper is part of the brain’s mid-level vision process.
But interpreting these as forming a human or creature shape would be high-level vision.
“Though ancient and modern cultures adopted different names and stories for asterisms, more than a few asterisms are recognised across multiple cultures,” Professor Kemp says. “We learned that basic aspects of our vision system may explain more about constellations across cultures than previously recognised.”
So the Pleiades attract eyes across the world because they’re a magical cluster of glittering dots. Orion’s belt features across most cultures because of its symmetry.
And that’s why these same patterns became carriers of so many different cultures’ unique learnings, lore and mythologies.