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.

                               2020 August 19

                              The Sun Rotating
         Video Credit: SDO, NASA; Digital Composition: Kevin M. Gill

   Explanation: Does the Sun change as it rotates? Yes, and the changes
   can vary from subtle to dramatic. In the featured time-lapse sequences,
   our Sun -- as imaged by NASA's Solar Dynamics Observatory -- is shown
   rotating though an entire month in 2014. In the large image on the
   left, the solar chromosphere is depicted in ultraviolet light, while
   the smaller and lighter image to its upper right simultaneously shows
   the more familiar solar photosphere in visible light. The rest of the
   inset six Sun images highlight X-ray emission by relatively rare iron
   atoms located at different heights of the corona, all false-colored to
   accentuate differences. The Sun takes just under a month to rotate
   completely -- rotating fastest at the equator. A large and active
   sunspot region rotates into view soon after the video starts. Subtle
   effects include changes in surface texture and the shapes of active
   regions. Dramatic effects include numerous flashes in active regions,
   and fluttering and erupting prominences visible all around the Sun's
   edge. Presently, our Sun is passing an unusually low Solar minimum in
   activity of its 11-year magnetic cycle. As the video ends, the same
   large and active sunspot region previously mentioned rotates back into
   view, this time looking different.

                       Tomorrow's picture: open space
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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.


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