The distance to the swirling grand design spiral M100 is causing quite a stir among astronomers. Many believe that the Hubble Space Telescope 's recent distance measurement to this galaxy accurately calibrates the expansion rate of the universe . Others believe this distance measurement is misleading. The universe's expansion rate is usually given as a quantity called “ Hubble's constant ”, a factor dividing well-measured recession velocity of a galaxy to give actual distance. Scientific debate over the value of Hubble's constant has been ongoing since it was first measured by Edwin Hubble in 1929. A real live debate involving the value of Hubble's constant titled “ The Scale of the Universe ” will occur in April 1996 in Washington, DC.
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Credit: NASA, HST, W. Freedman (CIW), R. Kennicutt (U. Arizona), J. Mould (ANU)