                        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 December 31

                   Illustris: A Simulation of the Universe
   Video Credit: Illustris Collaboration, NASA, PRACE, XSEDE, MIT, Harvard
                                    CfA;
           Music: The Poisoned Princess (Media Right Productions)

   Explanation: How did we get here? Click play, sit back, and watch. A
   computer simulation of the evolution of the universe provides insight
   into how galaxies formed and perspectives into humanity's place in the
   universe. The Illustris project exhausted 20 million CPU hours in 2014
   following 12 billion resolution elements spanning a cube 35 million
   light years on a side as it evolved over 13 billion years. The
   simulation tracks matter into the formation of a wide variety of galaxy
   types. As the virtual universe evolves, some of the matter expanding
   with the universe soon gravitationally condenses to form filaments,
   galaxies, and clusters of galaxies. The featured video takes the
   perspective of a virtual camera circling part of this changing
   universe, first showing the evolution of dark matter, then hydrogen gas
   coded by temperature (0:45), then heavy elements such as helium and
   carbon (1:30), and then back to dark matter (2:07). On the lower left
   the time since the Big Bang is listed, while on the lower right the
   type of matter being shown is listed. Explosions (0:50) depict
   galaxy-center supermassive black holes expelling bubbles of hot gas.
   Interesting discrepancies between Illustris and the real universe have
   been studied, including why the simulation produced an overabundance of
   old stars.

                     Tomorrow's picture: a grand design
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
                NASA Web Privacy Policy and Important Notices
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

