                        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 September 22
    The planet Saturn is pictured 6 times in a horizonal column, labelled
     by years with 2020 at the top and 2025 at the bottom. As the years
        progress, Saturn's ring appear less prominent. Please see the
                 explanation for more detailed information.

                              Equinox at Saturn
                   Image Credit & Copyright: Imran Sultan

   Explanation: On Saturn, the rings tell you the season. On Earth, today
   marks an equinox, the time when the Earth's equator tilts directly
   toward the Sun. Since Saturn's grand rings orbit along the planet's
   equator, these rings appear most prominent -- from the direction of the
   Sun -- when the spin axis of Saturn points toward the Sun. Conversely,
   when Saturn's spin axis points to the side, an equinox occurs, and the
   edge-on rings are hard to see from not only the Sun -- but Earth. In
   the featured montage, images of Saturn between the years of 2020 and
   2025 have been superposed to show the giant planet passing, with this
   year's equinox, from summer in the north to summer in the south.
   Yesterday, Saturn was coincidently about as close as it gets to planet
   Earth, and so this month the ringed giant's orb is relatively bright
   and visible throughout the night.

               Tomorrow's picture: cathedral to massive stars
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                           NASA Science Activation
                             & Michigan Tech. U.

