October 26, 1994: Astronomers using the Hubble telescope have announced the most accurate distance measurement yet to the remote galaxy M100, located in the Virgo cluster of galaxies.
This measurement will help provide a precise calculation of the expansion rate of the universe, called the Hubble Constant, which is crucial to determining the age and size of the universe. They calculated the distance - 56 million light-years - by measuring the brightness of several Cepheid variable stars in the galaxy. Cepheid variables are a class of pulsating star used as "milepost markers" to calculate the distance to nearby galaxies. The bottom image shows a region of M100. This Hubble telescope image is a close-up of a region of the galaxy M100. The top three frames, taken over several weeks, reveal the rhythmic changes in brightness of a Cepheid variable.See the rest:
Key Project Team: Sandra Faber, Garth Illingworth & Dan Kelson (Univ. of California, Santa Cruz), Laura Ferrarese & Holland Ford (Space Telescope Science Institute), Wendy Freedman, John Graham, Robert Hill & Randy Phelps (Carnegie Institution of Washington), James Gunn (Princeton University), John Hoessel & Mingsheng Han (University of Wisconsin), John Huchra (Harvard-Smithsonian Center for Astrophysics), Shaun Hughes (Royal Greenwich Observatory), Robert Kennicutt, Paul Harding, Anne Turner & Fabio Bresolin (Univ. of Arizona), Barry Madore & Nancy Silbermann (JPL, Caltech), Jeremy Mould (Mt. Stromlo, Australian National University), Abhijit Saha (Space Telescope Science Institute), and Peter Stetson (Dominion Astrophysical Observatory).