                        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.

                               2023 January 9

                             Tails of Comet ZTF
              Image Credit & Copyright: Jose Francisco Hernández

   Explanation: Comet ZTF may become visible to the unaided eye.
   Discovered early last year, this massive snowball has been brightening
   as it approaches the Sun and the Earth. C/2022 E3 (ZTF) will be closest
   to the Sun later this week, at which time it may become visible even
   without binoculars to northern observers with a clear and dark sky. As
   they near the Sun, comet brightnesses are notoriously hard to predict,
   though. In the featured image taken last week in front of a picturesque
   star field, three blue ion tails extend to the upper right, likely the
   result of a variable solar wind on ions ejected by the icy comet
   nucleus. The comet's white dust tail is visible to the upper left and
   much shorter. The green glow is the comet's coma, caused by glowing
   carbon gas. Comet ZTF is expected to pass nearest the Earth in early
   February, after which it should dim dramatically.

   Discovery + Outreach: Graduate student research position open for APOD
                    Tomorrow's picture: interstellar cone
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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