                        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 December 31
   A starfield filled with a diffuse red glow has an unusual nebula on the
     lower left. The nebula has bright red filaments that curve down and
      appear to be reminiscent of a waterfall on Earth. Please see the
                 explanation for more detailed information.

                        HH-222: The Waterfall Nebula
                    Image Credit & Copyright: Mike Selby

   Explanation: What created the Waterfall Nebula? The origin is still
   being researched. The structure, officially designated Herbig-Haro 222,
   appears in the region of NGC 1999 in the Great Orion Molecular Cloud
   complex. The elongated gaseous stream stretches about ten light years
   but appears similar to a long waterfall on Earth. Recent observations
   indicate that HH-222 is likely a gigantic gaseous bow shock, similar to
   a wave of water caused by a fast-moving ship. The origin of this shock
   wave is thought to be a jet outflow from the multiple star system V380
   Orionis off the lower left of the frame. Therefore, gas does not flow
   along the waterfall, but rather the entire structure moves toward the
   upper right. The Waterfall Nebula lies about 1,500 light years away
   toward the constellation of Orion. The featured image was captured
   earlier this month from El Sauce Observatory in Chile.

                 Jigsaw Nebula: Astronomy Puzzle of the Day
                       Tomorrow's picture: open space
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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