                        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 November 17

                       NGC 3314: When Galaxies Overlap
      Image Credit: NASA, ESA, Hubble; Processing & Copyright: William
                     Ostling (The Astronomy Enthusiast)

   Explanation: Why doesn't the nearby galaxy create a gravitational
   lensing effect on the background galaxy? It does, but since both
   galaxies are so nearby, the angular shift is much smaller than the
   angular sizes of the galaxies themselves. The featured Hubble image of
   NGC 3314 shows two large spiral galaxies which happen to line up
   exactly. The foreground spiral NGC 3314a appears nearly face-on with
   its pinwheel shape defined by young bright star clusters. Against the
   glow of the background galaxy NGC 3314b, though, dark swirling lanes of
   interstellar dust can also be seen tracing the nearer spiral's
   structure. Both galaxies appear on the edge of the Hydra Cluster of
   Galaxies, a cluster that is about 200 million light years away.
   Gravitational lens distortions are much easier to see when the lensing
   galaxy is smaller and further away. Then, the background galaxy may
   even be distorted into a ring around the nearer. Fast gravitational
   lens flashes due to stars in the foreground galaxy momentarily
   magnifying the light from stars in the background galaxy might one day
   be visible in future observing campaigns with high-resolution
   telescopes.

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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
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