The Twins and Mnemonics
The Twins and Mnemonics
In legends the Twins—Gemini—are thought of as helpers. The Kiowa tribe of the western United States see them as part of the constellation of the Bear’s Lodge where girls who were about to be eaten by bears were rescued by the stars. For the Romans, they were the guardians of their city, having intervened for Rome in the battle of Lake Regillus. Sailors have thought that the electrical glow called “St. Elmo’s Fire” that sometimes appears in a ship’s rigging during a storm was a sign of the stars’ protection and the end of the storm. Then there’s the story of the Twins, a poet, a king, and a memory aid.
Gemini from Uranometria, courtesy of Linda Hall Library of Science, Engineering & Technolog y
The constellation with the twin stars is overhead at midnight about January 15. It was appearing in the east late at night most of the fall. Besides the two bright stars, there is also one Messier object in Gemini, the star cluster M35; there is a second star cluster NGC 2158, and a nebula NGC 2392 known as the Eskimo or the Clown-face Nebula.
Eskimo Nebula, Courtesy NASA
Castor, the dimmer of the two Twins, has a magnitude of 1.93. Its light is of varying intensity. This prompted astronomers to discover that it wasn’t one star. When they found a second revolving around it, they were able to show that the force of gravity applies beyond our planet. Not only does Castor itself have a twin with almost the same luminosity, it also has a third, red dwarf that is part of the system, and – each of three is a double, making the whole not merely one part of the Twins but in themselves a sextuplet.
The revolving stars of Castor and other binary stars have been particularly important because their varying luminosity has helped astronomers study their physical properties. From these studies scientists have gone on to discoveries about the relative mass of objects in space, their distances, and their ages. Pollux is a brighter yellowish star with a magnitude of 1.16, making it the 17th brightest star in the sky. It’s thought that one of the two Twins’ luminosity has changed significantly since they were named because Castor is called “alpha” and Pollux is “beta.” Pollux is about 4.5° south-southeast of Castor. This separation is about the distance measured by the second joint of your index finger held out at arm’s length against the sky. It’s this nearness to each other that has made them “the Twins.”
In Greek myth Castor and Pollux were sons of Zeus and Leda, and also brothers of Helen of Troy. They had several adventures rescuing Helen from Theseus (not Paris!), and going with Jason on his Argonaut. Castor was known as a horseman, Pollux as a boxer; and they were in charge of the public games. Perhaps because they were patrons of hospitality they were both considered handsome. The Twins and memory tricks
The story goes like this, according to the Roman essayist Cicero: Simonides, a 6th century Greek poet, was hired by Scopas, a rich, self-important king, to sing his praises at a party. However, the poet decided not to pander to the king’s vanity, but instead included more references in his song to Castor and Pollux than to Scopas. Incensed, Scopas exploded, “You think I’m going to pay you for that? Go try to get your pay out of the Twins. If they’re still around.”
Just then, a servant called Simonides out, saying that a couple of boys wanted to see him. He went, but no one was there. At that moment the dining room collapsed and everyone inside was killed, their bodies too smashed to be recognizable. Naturally Simonides believed that the Twins helped him escape. The story has an interesting twist: Because Simonides could recall where each person had sat at the banquet, he was able to identify the bodies. Cicero says that the poet was the first one to realize “that order is what brings maximum light to memory” and to come up with the idea of “the art of memory,” or mnemonics. Do you think he thanked his lucky stars for that also?