                        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.

                                2025 April 10

                         38 Hours with the M81 Group
                  Image Credit & Copyright: Daniel Yang K.

   Explanation: From a garden on planet Earth, 38 hours of exposure with a
   camera and small telescope produced this cosmic photo of the M81 galaxy
   group. In fact, the group's dominant galaxy M81 is near the center of
   the frame sporting grand spiral arms and a bright yellow core. Also
   known as Bode's galaxy, M81 itself spans some 100,000 light-years. Near
   the top is cigar-shaped irregular galaxy M82. The pair have been locked
   in gravitational combat for a billion years. Gravity from each galaxy
   has profoundly affected the other during a series of cosmic close
   encounters. Their last go-round lasted about 100 million years and
   likely raised density waves rippling around M81, resulting in massive
   star forming regions arrayed along M81's spiral arms. M82 was left with
   violent star forming regions too, and colliding gas clouds so energetic
   that the galaxy glows in X-rays. In the next few billion years, their
   continuing gravitational encounters will result in a merger, and a
   single galaxy will remain. Another group member, NGC 3077 is below and
   left of the large spiral M81. Far far away, about 12 million
   light-years distant the M81 group galaxies are seen toward the northern
   constellation Ursa Major (the Great Bear). But in the closer foreground
   the wide-field image is filled with integrated flux nebulae whose
   faint, dusty interstellar clouds reflect starlight above the plane of
   our own Milky Way galaxy.

                        Tomorrow's picture: a matinee
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                             & Michigan Tech. U.

