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.

                                2019 July 10

                               4000 Exoplanets
      Video Credit: SYSTEM Sounds (M. Russo, A. Santaguida); Data: NASA
                              Exoplanet Archive

   Explanation: Over 4000 planets are now known to exist outside our Solar
   System. Known as exoplanets, this milestone was passed last month, as
   recorded by NASA's Exoplanet Archive. The featured video highlights
   these exoplanets in sound and light, starting chronologically from the
   first confirmed detection in 1992. The entire night sky is first shown
   compressed with the central band of our Milky Way Galaxy making a giant
   U. Exoplanets detected by slight jiggles in their parents-star's colors
   (radial velocity) appear in pink, while those detected by slight dips
   in their parent star's brightness (transit) are shown in purple.
   Further, those exoplanets imaged directly appear in orange, while those
   detected by gravitationally magnifying the light of a background star
   (microlensing) are shown in green. The faster a planet orbits its
   parent star, the higher the accompanying tone played. The retired
   Kepler satellite has discovered about half of these first 4000
   exoplanets in just one region of the sky, while the new TESS mission is
   on track to find even more, all over the sky, orbiting the brightest
   nearby stars. Finding exoplanets not only helps humanity to better
   understand the potential prevalence of life elsewhere in the universe,
   but also how our Earth and Solar System were formed.

   Note: Today's POD is a video in mp4 format.

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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                             & Michigan Tech. U.
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