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APOD
Astronomy Picture of the Day
Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
M100 and the Expanding Universe
Explanation: 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.
| Date | January 9, 1996 |
|---|---|
| Credit | Credit: NASA, HST, W. Freedman (CIW), R. Kennicutt (U. Arizona), J. Mould (ANU) |
| Authors & editors: | Robert Nemiroff (MTU) & Jerry Bonnell (UMCP) |
| A service of: |
ASD at NASA / GSFC, NASA Science Activation & Michigan Tech. U. |