“There really isn’t a dinosaur constellation, right?” I didn’t ask anyone out loud as I watched the stars twinkle in the dark.
Moments earlier I had driven through the town of Dinosaur, Colorado. Now, as darkness fell around my car, I thought I spotted a sauropod among the stars through my driver’s window. I chuckled to myself, feeling foolish for seeing dinosaurs where there certainly weren’t, and attributed it to the power of suggestion.
But apparently I wasn’t just silly. I was participating in a human tradition that dates back millennia, says Daniel Brown, associate professor of astronomy and science communication at Nottingham Trent University in England. The night sky, he says, is “an ideal canvas” for viewers to interpret and find visualizations of something that is relevant to their lives. “This is how we would normally begin to refer to constellations.”
But the constellations are not just a sketch of each individual’s imaginative ideas. The way the stars are splashed across the sky invites humans to see certain patterns. In fact, despite viewing the sky from distinct angles, many cultures around the world have identified clusters of stars in remarkably similar ways. Those parallels and differences offer a reflection of the astronomical dynamics taking place in the night sky, as well as the values and mentalities of the people who watch it.
One constellation, two stories
Constellations have long served as maps for navigation, canvases for storytelling, calendars for seasonal changes, and charts through which to impart knowledge and meaning.
“Until recently in human history we had no structured, written languages. The language was communicated orally, “says Duane Hamacher, associate professor of cultural astronomy at the University of Melbourne in Australia.” But the human brain has evolved to be able to store huge amounts of information. One way to do this is. associating a memory with a place, called the loci method, which, he explains, includes the stars.
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By transmitting knowledge of the constellations, profound cultural memories persist. Today, researchers have noticed a pattern: Many of the brightest stars are clustered in strikingly similar constellations across cultures that historically had no known contact with each other. Western astronomers may be familiar with some of those star clusters such as Ursa Major, Orion, the Pleiades, and the Southern Cross.
These particular clusters of stars attract attention with their brightness and proximity to each other in the night sky, attracting star observers from both hemispheres, according to a team of researchers from the University of Melbourne. The researchers used a mathematical model to systematically group stars based on their importance and proximity and compare these groupings with constellations from 27 different cultures around the world. This process tested what is considered a principle of how human visual perception works: the Gestalt Law of Proximity, which states that objects close to each other are perceived as unified groups, regardless of how different they may be individually. In an article published earlier this year in the magazine Psychological SciencesUniversity of Melbourne experts found that these perception principles likely explain why so many different cultures have grouped the same stars into constellations.
But the similarities don’t stop at the stars where people visually cluster. Humans have often mapped familiar images and stories to those dots of light. And even those stories are often surprisingly similar, despite being influenced more by the cultural context than by the characteristics of the stars themselves.
For example, says Hamacher, who is an author of Psychological Sciences paper, the male figure of Orion is often seen as one or more men chasing a group of girls or women, whom the ancient Greeks called the Pleiades. A V-shaped group of stars, the Hyades, lie between them and Orion. There are subtle differences, he says, in the cultural interpretations of this constellation of guardians. The Greek version has Hyades appearing as Taurus, the bull that prevents Orion from reaching the girls. Meanwhile, some Australian Aboriginal traditions tend to depict Orion as a womanizer who falls in love with his sisters, but their older brother stands in the way of him.
In many of the versions of the story, the details of this search and defense reflect the movement and dynamics of the stars themselves. Due to the Earth’s rotation, these constellations move across the sky throughout the night, with Orion appearing to be chasing the Pleiades. Some Aboriginal cultures see Orion upside down with the red star Betelgeuse in his right hand as fire magic the warrior creates to fight his older sister, says Hamacher. Meanwhile, the red star Aldebaran in his left foot (often seen as the bull’s red eye in Greek lore) is about to kick sand in his face. The magic of the fire flickers and grows as they face each other, reflecting how Betelgeuse, which is a variable star, dims and lights up in 400 days.
From legends to machines
The length of time people have created stories about shapes in the sky is also important. For example, Brown says, many of the constellations of Western culture seen from the Northern Hemisphere are more mystical creatures and tales, based on Greek mythology. Those constellations were described in an anthropology of constellation histories written in the third century BCE, so many were likely identified much earlier. Thousands of years later, Western explorers in the Southern Hemisphere have documented the patterns they have seen in the stars during their travels to include more technical instruments, particularly navigational instruments, such as a sextant or compass.
“You will find a lot of things that are much more associated with the Age of Discovery,” says Brown. “Unsurprisingly, our cultural group began exploring the southern hemisphere at a time when all of these clocks and things would have been so much more important.”
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But what those Western explorers didn’t consider, Brown says, were those star clusters that had been identified and named thousands of years earlier in the Southern Hemisphere night sky by people who already lived there, with very different interpretations.
“This is why I always stress that the Western and Greek constellations are just one way these patterns can be interpreted,” notes Brown. Listening to the ways people around the world make sense of the patterns they see in the stars can illuminate aspects of their culture and what is relevant to them.
Hamacher and his colleagues are conducting experiments to see what kind of constellations people create for themselves. In a planetarium, they present to the public a simulated night sky with stars in false positions. When modern viewers connect the dots to create shapes, he says, it reflects their culture and geography. “You won’t have many Australians who will see a squirrel in the stars and Americans won’t see a koala,” says Hamacher.
Constellations without stars
Stars aren’t the only thing visible in the night sky, adds Hamacher – there are also nebulae, planets and the moon. And in some parts of the world, the night sky becomes dark enough to see dark voids where starlight is absent in the Milky Way.
In the Southern Hemisphere, those spaces are often plotted in what are called dark constellations. As the air is much less humid in Australia than in many other parts of the world, the continent is a particularly good place to see some of the darkest night skies.
Some cultures see similar patterns in dark constellations as well. For example, says Hamacher, Aboriginal cultures see an emu in the dark space of the Milky Way between the Southern Cross and Sagittarius. In South America, some people also see a large flightless bird called rhea.
Many star patterns appear only at certain times of the year (others, which linger near the poles, are visible all year round). In Australia, the emu begins to become visible in the evening during the same time of year that birds breed, build their nests and lay their eggs. Because people typically went out and looked for those eggs, Hamacher says, the seasonal appearance of the dark emu constellation also served as a sort of harvest calendar for people.
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Light pollution can be another factor in how different people view the stars. Today, artificial light bulbs that illuminate the night also interfere with starlight, fading the Milky Way and all but the brightest stars for millions of residents in urban, suburban and adjacent areas.
“But they don’t completely fade away. I just have to go through my Stellarium app, “says Brown, referencing an app to help users identify constellations.” We still have access and knowledge of what’s in the sky. Now we engage with the sky in a completely different, in this kind of virtual way “.
Constellation apps also give viewers access to knowledge of the night sky from around the world. Users can see the various cultural interpretations of the patterns of the stars arranged on their screens as they scan the night sky.
“You can get to know so many other cultures because you can look at the sky. You are immediately in contact with something that someone in the depths of the Amazon could see and that someone could have seen while they were building the pyramids, ”says Brown. “This is our shared heritage”.
The post Why We Turn Stars into Constellations first appeared in Popular Science.