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.

2002 May 6
See Explanation.  Clicking on the picture will download
 the highest resolution version available.

NGC 4676: When Mice Collide
Credit: ACS Science & Engineering Team, NASA

Explanation: These two galaxies are pulling each other apart. Known as "The Mice" because they have such long tails, each spiral galaxy has likely already passed through the other and will probably collide again and again until they coalesce. The long tails are created by the relative difference between gravitational pulls on the near and far parts of each galaxy. Scrolling right will show the very long tail of one of the galaxies. Because the distances are so large, the whole thing takes place in slow motion -- over hundreds of millions of years. NGC 4676 lies about 300 million light-years away toward the constellation of Coma Berenices and are likely members of the Coma Cluster of Galaxies. The above picture was taken with the Hubble Space Telescope's new Advanced Camera for Surveys which is more sensitive and images a larger field than previous Hubble cameras. The camera's increased sensitivity has imaged, serendipitously, galaxies far in the distance scattered about the frame.

Tomorrow's picture: Smog Over New York

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
& Michigan Tech. U.