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Leavitt,
Henrietta Swan American astronomer Born: Lancaster Massachusetts, July 4, 1868 Died: Cambridge, Massachusetts, December 12, 1921 | |||||||||
Brahe Galileo Herschel Hevelius Hubble Kepler Leavitt Messier Shapley |
Henrietta Leavitt was an astronomer at the Harvard College Observatory, where she studied the Magellanic clouds in 1912. These clouds are large star collections which exist outside our galaxy. She was particularly interested in certain stars that display periodic variations in brightness. These type of stars are known as Cepheids, because the first one studied was in the constellation of Cepheus. Miss Leavitt noticed that the greater the brightness of the star, the longer the period was, of the variation in brightness. It thus became possible to devise a period-luminosity curve in which the true brightness, as shown by the period of variation, could be compared to the apparent brightness. Even the nearest Cepheid is too far away to calculate it's distance by using the usual parallax method developed by Bessel. There are, however, other methods and once the distance to one Cepheid had been calculated by Herzsprung, the period-luminosity curve was applied by Leavitt and Shapley, to provide a method to calculate the distance to other distant stars. This method can only be used for stars outside of our own galaxy, as our own stars are too close for it to work properly. This discovery of Henrietta Leavitt concerning the Cepheids provided the first method of determining vast stellar distances. Another method was to be provided by Hubble. | |||||||||
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