Over the last year, several dozen new constellations have appeared, with names that refer to heroes of science and science fiction. It isn’t that a plethora of new stars have suddenly emerged in the sky, but that our technology has advanced enough to detect them. And not only that, but thanks to modern space telescopes, which bring us closer to stars from other galaxies —too far away to see their light with the naked eye— we can even detect totally invisible points of radiation (gamma ray emissions). NASA scientists have joined up some of these points so that Einstein, the Hulk or the Enterprise from Star Trek have their place in the firmament, even if it’s in a different dimension to that of the Great Bear, Orion or Scorpio.
In the end it’s the same thing that we humans have been doing for countless centuries: looking at the sky and trying to assimilate it by finding familiar shapes in the stars, which represent animals, heroes or our most beloved stories. Anyone can create their own constellations in this way; we only have to head out into the countryside to see the stars, and under a very dark sky we have up to 3,000 stars at our fingertips with no other astronomical tools needed than our own eyes. Once there the brain will do the rest and the first constellations will begin to appear.
Joining dots in the sky, a tale as old as time
Our brain is designed to recognise patterns, and it does so very well. Thanks to this ability we can recognise a family member or a friend in a crowd almost instantly. This ability has side effects, such as pareidolias, which leads us to recognise things or animals in the clouds or even to see Jesus Christ on a slice of toast, or a face on the surface of Mars. Something like this happens with the stars. The brain combines them as in the classic game of drawing by joining dots, until it has a known shape. A constellation is nothing more than that, an arbitrary drawing made with stars that are in the same area of the sky but have no relation to one another.
Each ancient culture thus established its own constellations, sometimes identifying different shapes and other times naming the same shapes differently. Astronomers have divided the sky into 88 official constellations —registered by the International Astronomical Union— as if they were plots on a city map. In the northern hemisphere, we use those seen by the ancient Greeks, whose civilisation was the cradle of science, and who imagined the scenes and protagonists of their myths in the sky. At that time, that was the biggest entertainment platform: telling stories before the heat of a bonfire and with the visual support of the stars overhead.
That’s how the constellation of the Great Bear (Ursa Mayor) came about. Its origin is found in the myth of Callisto, a nymph whom the god Zeus lusted after. Arcas was born out of the relationship between the god and the muse. When Artemis found out, he punished Callisto, turning her into a bear condemned to wander through the woods without being able to be with her son. Many years later, Arcas became a great hunter, and on a hunting trip he came across his mother, but didn’t recognise her because in his eyes she was a dangerous bear. Calisto recognised him, however, and instead of confronting him, she put herself within range of his bow, resigned to being killed by her own son. Legend has it that Zeus then stopped Arcas, explained what had happened and decided to raise the two to the heavens where they remain eternally together.
Carl Sagan reviewed in his Cosmos TV series interpretations of Ursa Major made by different cultures.
The current popular names of this constellation have to do with more everyday things: in the USA and Canada it is known as the Big Dipper, while in Ireland and the United Kingdom the seven stars of Ursa Major are identified with a Plough and have been the symbol of political movements of the left. Previously, in the Germanic and Scandinavian languages it was known as the Wagon or Charles’s Wain (which is erroneously associated with Charlemagne), while in the Hindu tradition they represent “the seven wise men of antiquity”, in Malaysia they are identified with a ship, in Indonesia with a canoe and in Burma with a crustacean.
From Ursa Mayor to the Enterprise
Not all the 88 constellations have their origin in the Greek tradition, such as Ursa Major, since all the stars of the firmament cannot be seen from the Mediterranean. Western civilisation and science emerged only with the knowledge of the stars of the northern hemisphere. It was the sailors, explorers and naturalists of the 17th and 18th centuries who gave names to the new constellations found on their travels to other latitudes. The French astronomer and mathematician Nicolás-Louis de Lacaille saw in the southern hemisphere sky some of his favourite scientific instruments: constellations such as Fornax (the chemical furnace), Microscopium (the microscope), Telescopium (the telescope) or Antila Pneumatica (the air pump), as well as naval references such as Pyxis (the mariner’s compass), Carina (the keel) or Puppis (the poop deck). Compared with the Greek names —Aries (the ram), Lyra (the harp) or Cygnus (the swan)— they sound much more modern, even if they were not new constellations: European scholars simply superimposed them over the ones already imagined by the civilisations and peoples of America and Southern Africa, as well as Oceania.
Now that the whole planet has been explored, there is no more sky to be discovered from Earth and thus there is no way to extend the planisphere with new constellations, at least not visible ones. Nevertheless, we know that stars, apart from emitting light, give off other types of radiation invisible to the human eye: infrared, radio waves, x-rays or gamma rays are some of the other frequencies that space telescopes can detect, and that serve to inform us about astronomical objects such as black holes or active galaxies.
This is the reason for the Fermi Gamma Ray Space Telescope, which recently completed a sweep of the sky collecting gamma light. The team of NASA scientists who explore the universe with this space telescope found themselves with a new “gamma planisphere” full of dots. Following the millenary tradition, they drew their favourite figures by connecting these dots and then named 21 new constellations —as real as ever, but invisible to the human eye. Among them are Schrödinger’s Cat, the Starship Enterprise, the Little Prince and Godzilla.
These new constellations are a stunt, of course, but the wait to assign a new name to a constellation would be very long. We would have to move far away from the Earth — the same constellations are seen from the other planets in the solar system— to obtain a different perspective on the sky, so that the stars would change the apparent distances between them significantly and, therefore, would form different. It would take centuries of interstellar travel, many light-years away. Another option would be to rely on humanity to survive hundreds of thousands of more years, until the expansion of the universe changes the actual distance between the stars so much that their distribution in our sky varied appreciably. Meanwhile, we can always go out and observe the sky as it is today and invent our own constellations, or enjoy the traditional constellations that have been with us since antiquity.