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 November 23

                          A Jupiter Vista from Juno
    Image Credit: NASA/JPL-Caltech/SwRI/MSSS; Processing & License: Kevin
                                  M. Gill;

   Explanation: Why do colorful cloud bands encircle Jupiter? Jupiter's
   top atmospheric layer is divided into light zones and dark belts that
   go all the way around the giant planet. It is high horizontal winds --
   in excess of 300 kilometers per hour -- that cause the zones to spread
   out planet-wide. What causes these strong winds remains a topic of
   research. Replenished by upwelling gas, zonal bands are thought to
   include relatively opaque clouds of ammonia and water that block light
   from lower and darker atmospheric levels. One light-colored zone is
   shown in great detail in the featured vista taken by the robotic Juno
   spacecraft in 2017. Jupiter's atmosphere is mostly clear and colorless
   hydrogen and helium, gases that are not thought to contribute to the
   gold and brown colors. What compounds create these colors is another
   active topic of research -- but is hypothesized to involve small
   amounts of sunlight-altered sulfur and carbon. Many discoveries have
   been made from Juno's data, including that water composes an
   unexpectedly high 0.25 percent of upper-level cloud molecules near
   Jupiter's equator, a finding important not only for understanding
   Jovian currents but for the history of water in the entire Solar
   System.

                       Tomorrow's picture: helical sky
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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.

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