If you’ve ever gazed at the night sky and attempted to outline the constellations with your forefinger, you may have found yourself asking the age old question “How the *@&$ is that supposed to be a crab?” You are not alone. Many astronomers will agree that very few constellations actually resemble the creature they supposedly represent. Most have attributed this discrepancy to a high likelihood that the ancients were drunk when naming these sets of stars. Although this may have been true, it is not the whole story. As a change of pace, in this astrobite we’ll guide you through a tale as old as time, taking a tongue-in-cheek look at some of the mythology that governs the cosmos.
These star stories are full of drama and flawed characters that make day time television look like a walk in the park. Apparently the human struggle has changed little since the days of Claudius Ptolemy, the Greek astronomer that is often credited with naming the constellations. In reality, many different cultures across the globe have created their own traditions around the stars. Some of the oldest astronomical recordings and tools are from Babylon (~1900-500 BCE), which was located in present-day Iraq. The Babylonians developed the first recorded inklings of astrology (yes, we are talking about astrology now) and therefore the most famous constellations; those of the Zodiac. Their science and ways of thinking about the heavens influenced ancient Greek mathematicians, and finally made their way to Ptolemy around ~100 CE. Ptolemy lived in Egypt, which at the time was part of the Roman empire, and his independent work influenced much scientific theory in this part of the globe. He eventually wrote a book (the reason he gets all the credit) called Almagest, which named and defined 48 constellations. These 48 constellations are still included in the 88 constellations currently recognized by the IAU. Therefore, we will focus on the Greek versions of these myths, although there are many other great stories that exist.
Orion the Hunter & Scorpio the Scorpion
There are many versions of this myth, but perhaps the most exciting is that of Orion and Scorpio. Orion was a fantastic huntsman, but he was also kind of a jerk. Some say that Orion was the son of Poseidon, the god of the sea, and that he was strolling along the ocean one day when he landed on the island of Chios. He proceeded to get drunk and attack one of the king’s children, which really sent the king into a tizzy. The king blinded Orion for being such a jerk, but the sun god, Helios, later healed him (for some unknown reason).
Apparently getting blinded did nothing to deflate Orion’s massive ego. One day he was hunting with Artemis, the goddess of the hunt, when he grew too big for his britches. He claimed that he was simply the best huntsman there was and that he would kill all the beasts of the Earth. Well, Earth wasn’t very happy about this, understandably. Artemis’ twin brother Apollo was also pretty agitated. Gaia (Mother Earth) and Apollo devised a plan to send Scorpio, a giant scorpion, to kill Orion in an epic battle. Of course, Scorpio won, because it was a giant scorpion. To commemorate this event, Zeus (the king of the gods) threw both Orion and Scorpio up into the heavens, 180 degrees apart so that they would no longer fight. Nowadays, you can see one rise as the other sets.
Orion is visible in both hemispheres and is best spotted by its belt, formed by three relatively bright stars (Mintaka, Alnilam, and Alnitak). The belt is actually an asterism, a set of stars within the constellation that is widely associated with it due to an easily identifiable pattern, but is not the constellation itself; other asterisms include the Big and Little Dipper (parts of Ursa Major and Minor), for example. In actuality, the constellation is not just comprised of the stars that make up Orion’s shape, but is instead an entire region of the sky (see Figure 2 – this applies to other constellations as well!).
Perseus the Hero & Pegasus the Winged Horse
The story of Perseus begins with his grandfather, a king named Acrisius. Acrisius, after speaking with an oracle one day, was told a prophecy that his grandson was destined to kill him (which eventually did happen, due to an accident with an ancient frisbee). In order to prevent this, Acrisius locked his only daughter, Danae, away in a chamber to keep her from ever having children. Psyche! Enter Zeus, who fell in love with Danae and came to visit her in the form of rain. Well, that rain got her pregnant (your guess is as good as mine) and Perseus was born. Danae’s father was quite alarmed, so he sent Danae and Perseus far away, across the ocean in… a box.
With the help of absent father Zeus, the box landed on an island called Seriphos, where a man named Dictys found the mother and child and took them in. Dictys had a brother who was again, a jerk, but he also happened to be the king. This king wanted Danae all to himself, because everyone in mythology is jealous of something. So, the king sent the young Perseus on an impossible mission which he was unlikely to survive: go kill Medusa and bring back her head.
How poor Medusa became so terrifying is another story, but you may know that she had snakes for hair and could turn anyone who gazed upon her face into stone. Perseus snuck up on her while she was sleeping in her sea cave, using his shield as a mirror to guide him and avoid directly looking at her. He cut off Medusa’s head and supposedly the snakes died too (her head is depicted in Perseus’ hand by the star Algol, the “Demon Star”, Fig. 3). Some of Medusa’s blood mixed with the water in the cave and from it sprang the beautiful winged horse Pegasus (water + blood = horse), and his brother Chrysaor, who was surprisingly not a horse. Pegasus is therefore considered to be the offspring of Poseidon and Medusa. Not only could he fly, but he created fresh springs of water wherever he stamped his hoof.
Pegasus was eventually tamed by a hero named Bellerophon, with the help of a golden bridle given to him by the goddess of war, Athena. Bellerophon needed Pegasus’ help to slay the Chimera, a fire-breathing monster with an identity crisis that is usually depicted as a lion/goat/snake all at once. The heroic pair defeated the Chimera, and went on many other adventures as best buds. But eventually, Bellerophon’s success went to his head, and he tried to fly on Pegasus’ back to join the gods on Mount Olympus. Of course, he fell off the horse’s back and died a very embarrassing death. Pegasus however did make it to Mount Olympus, where he carted Zeus’ chariot full of thunderbolts. Zeus eventually rewarded Pegasus with the seventh largest spot in the sky, but only the front half of the horse can be seen.. and it does actually look like a horse! (see Figure 4, which contains the asterism ‘The Great Square of Pegasus”)
Andromeda the Princess
Andromeda was said to be a beautiful princess but her parents, Queen Cassiopeia and King Cepheus of Ethiopia, were largely awful. Cassiopeia was also famed for her beauty, but she liked to talk about it too much. One day she was bragging about herself, claiming that she was more beautiful than all the Nereids, or sea nymphs. Poseidon was deeply offended by this blasphemy and had to retaliate or else he would look bad. Poseidon flooded the king and queen’s land and sent the great sea monster Cetus to gobble them all up.
Like any all-star parents would do, the king and queen decided to sacrifice Andromeda to Cetus, hoping that this would quench the monster’s thirst for blood. They chained her to a bunch of rocks and ran away like cowards.
Luckily, Perseus had just finished slaying Medusa, and was on his way home to kill all his enemies via exposing them to the detached head. He saw Andromeda chained up and released her, but Cetus was approaching. Perseus unveiled Medusa’s head and the sea monster turned to solid stone *gasp* (in some versions, he kills Cetus with a knife). Andromeda and Perseus got married and lived happily ever after, thank goodness. Andromeda was placed in the sky next to Perseus when she died, along with her parents and the sea monster Cetus. The constellation Andromeda shares a star with Pegasus, akin to how both the princess and the horse shared connections with Perseus. The princess’ constellation is home to our closest neighboring non-dwarf galaxy, also named Andromeda (see Figure 5).
Of course, we have only covered a small portion of 88 constellations, and there are many more stories out there. But perhaps when you gaze up at the night sky next, you can trace out the constellations in the sky, recall these stories, and say “… that still doesn’t look like a crab.”