A couple of weeks ago, I went to a “Night Skies” presentation at the local planetarium. There, I was intrigued to learn not only how to go about locating the Cassiopeia constellation in the northern night sky, but that the stars making up her spot are turned upside down half the year, putting Cassiopeia on her head, as a punishment.
First, Cassiopeia’s location—you can find her by looking for five really bright stars that zigzag to form a sort of W (or M, depending on your perspective). Second, I better tell you now that a constellation is simply a group of stars meant to form an image in the sky—mostly mythological characters.
How is it that Cassiopeia is upside down half the time? It’s because the top of Cassiopeia’s head is next to the North Star, Polaris, and she rotates around it—which means half the time, Cassiopeia is right side up, but the other half of the year, she’s upside down. Both being in the sky and the fact that she’s upturned have to do with Poseidon (or Neptune in Roman mythology) punishing Cassiopeia for her boastful vanity.
The story goes like this: A long, long time ago, Cassiopeia was Queen of Aethiopia, wife of King Cepheus, and mother of Princess Andromeda. She was also extremely beautiful, but when she bragged of being even more lovely than the Nereids (sea nymphs), they felt greatly insulted and told Poseidon all about it. (Note that some versions say Cassiopeia boasted of Andromeda’s beauty or of both their looks.) At any rate, Poseidon then sent the sea monster Cetus to ravage the coast of Aethiopia.
However, the Oracle of Ammon told King Cepheus he could appease Poseidon by sacrificing Andromeda to the sea monster. So King Cepheus and Queen Cassiopeia chained Princess Andromeda to the rocks along the seashore. But if you’ve ever watched the old 80s movie Clash of the Titans, you already know that Perseus swooped in riding Pegasus (the winged horse) to save Andromeda before Cetus got her. Perseus turned Cetus to stone using the head of Medusa, then married Andromeda.
According to the myth, though, Poseidon was still mad and decided to make Cassiopeia suffer by throwing her into the stars and humiliating her by having her image appear upside down half the year. I suppose my title “Why the Greeks Put Cassiopeia in the Night Sky” is wrong then—because, technically, it was Poseidon who supposedly cast Cassiopeia into the sky.
If you’re able to locate the Cassiopeia constellation in the night sky, the celestial objects that form this constellation are quite interesting. Cassiopeia contains two yellow hypergiant stars and one white hypergiant star. (Hypergiants are the largest stars in the universe.) But stars aren’t the only thing found in the Cassiopeia constellation. It also contains open clusters and nebulae, as well as a supernova remnant (what’s left behind after a star explodes) known as Cassiopeia A. Cassiopeia A is the brightest extrasolar radio source in the sky.
As I’m writing this, the Cassiopeia constellation also had 14 known star systems with exoplanets (planets outside of our own solar system). And of these, one star (HR 8832) is thought to have seven planets circling it. It all sort of boggles the mind. So even if it’s a bit chilly outside, if you happen to be awake on a clear night after sunset, step outside and look up toward the nighttime sky. See if you can find Cassiopeia. And if you’re lucky enough to have access to a telescope, hone in to see what you can see.
Happy Viewing! 🙂