                        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 August 21

                      Triple Transit and Mutual Events
                  Image Credit & Copyright: Christopher Go

   Explanation: These three panels feature the Solar System's ruling gas
   giant Jupiter on August 15 as seen from Cebu City, Phillipines, planet
   Earth. On that date the well-timed telescopic views detail some
   remarkable performances, transits and mutual events, by Jupiter's
   Galilean moons. In the top panel, Io is just disappearing into
   Jupiter's shadow at the far right, but the three other large Jovian
   moons appear against the planet's banded disk. Brighter Europa and
   darker Ganymede are at the far left, also casting their two shadows on
   the gas giant's cloud tops. Callisto is below and right near the
   planet's edge, the three moons in a triple transit across the face of
   Jupiter. Moving to the middle panel, shadows of Europa and Ganymede are
   still visible near center but Ganymede has occulted or passed in front
   of Europa. The bottom panel captures a rare view of Jovian moons in
   eclipse while transiting Jupiter, Ganymede's shadow falling on Europa
   itself. From planet Earth's perspective, similar mutual events, when
   Galilean moons occult and eclipse each other, can be seen every six
   years or so when Jupiter is near its own equinox.

                       Tomorrow's picture: RS Ophiuchi
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.


