                        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 April 7
   A bright spiral galaxy fills the image with blue spiral arms laced with
        red-brown dust. Please see the explanation for more detailed
                                information.

                    NGC 4414: A Flocculent Spiral Galaxy
     Image Credit: ESA/Hubble & NASA, O. Graur, S. W. Jha, A. Filippenko

   Explanation: How much mass do flocculent spirals hide? The featured
   image of flocculent spiral galaxy NGC 4414 was taken with the Hubble
   Space Telescope to help answer this question. Flocculent spirals --
   galaxies without well-defined spiral arms -- are a quite common form of
   galaxy, and NGC 4414 is one of the closest. Stars and gas near the
   visible edge of spiral galaxies orbit the center so fast that the
   gravity from a large amount of unseen dark matter must be present to
   hold them together. Understanding the matter and dark matter
   distribution of NGC 4414 helps humanity calibrate the rest of the
   galaxy and, by deduction, flocculent spirals in general. Further,
   calibrating the distance to NGC 4414 helps humanity calibrate the
   cosmological distance scale of the entire visible universe.

                      Tomorrow's picture: Moon sisters
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                  NASA Web Privacy, Accessibility, Notices;
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

