                        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.

                                2021 July 18

                     The Andromeda Galaxy in Ultraviolet
                   Image Credit: NASA, JPL-Caltech, GALEX

   Explanation: What does the Andromeda galaxy look like in ultraviolet
   light? Young blue stars circling the galactic center dominate. A mere
   2.5 million light-years away, the Andromeda Galaxy, also known as M31,
   really is just next door as large galaxies go. Spanning about 230,000
   light-years, it took 11 different image fields from NASA's Galaxy
   Evolution Explorer (GALEX) satellite telescope to produce this gorgeous
   portrait of the spiral galaxy in ultraviolet light in 2003. While its
   spiral arms stand out in visible light images, Andromeda's arms look
   more like rings in ultraviolet. The rings are sites of intense star
   formation and have been interpreted as evidence that Andromeda collided
   with its smaller neighboring elliptical galaxy M32 more than 200
   million years ago. The Andromeda galaxy and our own comparable Milky
   Way galaxy are the most massive members of the Local Group of galaxies
   and are projected to collide in several billion years -- perhaps around
   the time that our Sun's atmosphere will expand to engulf the Earth.

                    Tomorrow's picture: the galaxy above
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.


