There could be no turning back.Īs telescopes got bigger and better, astronomers kept adding more magnitudes to the bottom of the scale. we may designate as of the seventh magnitude." Thus did a new term enter the astronomical language, and the stellar magnitude system became open-ended. "Indeed, with the glass you will detect below stars of the sixth magnitude such a crowd of others that escape natural sight that it is hardly believable," he exulted in his 1610 tract Sidereus Nuncius. On turning his newly made telescopes to the sky, Galileo discovered that stars existed that were fainter than Ptolemy's sixth magnitude. Ptolemy's works remained the basic astronomy texts for the next 1,400 years, so everyone used the system of first to sixth magnitudes. Sometimes Ptolemy added the words "greater" or "smaller" to distinguish between stars within a magnitude class. 140 Claudius Ptolemy copied this system in his own star list. The faintest stars he could see he called "of the sixth magnitude." Around A.D. He called the brightest ones "of the first magnitude," simply meaning "the biggest." Stars not so bright he called "of the second magnitude," or second biggest. Hipparchus ranked his stars in a simple way. The story begins around 129 B.C., when the Greek astronomer Hipparchus produced the first well-known star catalog. Star magnitudes do count backward, the result of an ancient fluke that seemed like a good idea at the time. Ancient Origins of The Stellar Magnitude System But things are not so sensible in astronomy - at least not when it comes to the brightnesses of stars. When you gain weight, after all, the scale doesn't tell you a smaller number of pounds or kilograms. When the thing that you're measuring increases, the number gets bigger. Most ways of counting and measuring things work logically.
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