Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Working at Harvard College Observatory , Leavitt precisely calibrated the photographic magnitudes of 47 stars to which all other stars could be compared. Leavitt discovered and cataloged over 1500 variable stars in the nearby Magellanic Clouds . From this catalog, Leavitt discovered that brighter Cepheid variable stars take longer to vary, a fact used today to calibrate the distance scale of our universe .
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