Biography of Johann Bayer

    Johann Bayer was a German astronomer who did the majority of his work around the turn of the 17th century. He is credited with creating a comprehensive atlas of the stars, the Uranometria. The atlas was the first of its kind to represent the entire sky, as it was the first to include the stars around the South Pole. Bayer is also invented the nomenclature used for identifying stars visible to the naked eye, which is still the convention in modern astronomy.
    Bayer was born in Rhain in the German region of Bavaria in the year 1572. Twenty years later he enrolled in Ingolstadt University as a student of philosophy. He eventually received a law degree and moved to Augsburg. His interest in astronomy, however, persisted, and he published the Uranometria, his atlas of the heavens, on September 1, 1603. It contained 2,000 stars (1,200 of which were taken from the catalog of Tycho Brahe) in 49 constellations. He received 150 gulden from the city council of Augsburg for dedicating the atlas to two high-ranking citizens. Although the Uranometria was the most encompassing stellar atlas of its time, it was not without its flaws. For example, he labeled a part of a constellation the left side, where all astronomers before him had called it the right, which caused confusion among astronomers using the atlas.
    What is considered Bayer’s more significant achievement, however, is the nomenclature system he devised for designating stars visible to the naked eye. The system in place for identifying individual stars prior to Bayer’s method relied on verbal descriptions of the stars in each constellation. This was confusing for astronomers and often subject to much ambiguity. Bayer, wanting a more effective method, decided to assign each star in each constellation a letter of the Greek alphabet, usually based on decreasing magnitude. (for constellations with more than 24 stars, Latin letters were resorted to). He would then name the star that letter followed by the constellation it was in. For example, the two brightest stars in the constellation of Gemini are named Alpha Gemini and Beta Gemini respectively. Some stars, such as Alpha Centauri (the brightest star in the constellation Centaurus), were only first (carefully) observed in Bayer’s time, and are therefore only known by the names designated by this system. The system is still in use today, but Roman numerals are being implemented as more stars are discovered.
    Though Bayer was successful overall as an astronomer, not all of his ideas were widely adopted. For instance, Bayer once proposed renaming the constellations based on the Bible, with northern hemisphere constellations getting names from the New Testament, and the southern hemisphere constellations getting names from the Old Testament. This, of course, never achieved widespread acceptance.
    Johann Bayer died a bachelor in the year 1625, but not without leaving his enduring mark on modern astronomy.