                        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 September 20
      An artist's illustration pictures a cloudy red planet orbiting a
       distant red star. Near the exoplanet is a moon. Please see the
                 explanation for more detailed information.

                   Methane Discovered on Distant Exoplanet
     Illustration Credit: Ahmad Jabakenji (ASU Lebanon, North Star Space
                      Art); Data: NASA, ESA, CSA, JWST

   Explanation: Where else might life exist? One of humanity's great
   outstanding questions, locating planets where extrasolar life might
   survive took a step forward in 2019 with the discovery of a significant
   amount of water vapor in the atmosphere of distant exoplanet K2-18b.
   The planet and its parent star, K2-18, lie about 124 light years away
   toward the constellation of the Lion (Leo). The exoplanet is
   significantly larger and more massive than our Earth, but orbits in the
   habitable zone of its home star. K2-18, although more red than our Sun,
   shines in K2-18b's sky with a brightness similar to the Sun in Earth's
   sky. The 2019 discovery of atmospheric water was made in data from
   three space telescopes: Hubble, Spitzer, and Kepler, by noting the
   absorption of water-vapor colors when the planet moved in front of the
   star. Now in 2023, further observations by the Webb Space Telescope in
   infrared light have uncovered evidence of other life-indicating
   molecules -- including methane. The featured illustration imagines
   exoplanet K2-18b on the far right orbited by a moon (center), which
   together orbit a red dwarf star depicted on the lower left.

                        Tomorrow's picture: space tag
     __________________________________________________________________

       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.

