To mark the 100th anniversary of Edwin Hubble’s discovery of a Cepheid variable star, named V1, in the neighboring Andromeda galaxy, astronomers collaborated with the American Association of Variable Star Observers (AAVSO) to study the star. AAVSO observers followed V1 for six months, creating a graph—or light curve—that records the star’s rhythmic rise and fall in brightness. Based on this data, it was determined that the Hubble Space Telescope would record the star during its faintest and brightest hours.
Credit: NASA, ESA, Hubble Heritage Project (STScI, AURA), Robert Gendler.