                        Astronomy Picture of the Day

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                                 2024 May 3

                     Temperatures on Exoplanet WASP-43b
         Illustration Credit: NASA, ESA, CSA, Ralf Crawford (STScI)
     Science: Taylor Bell (BAERI), Joanna Barstow (The Open University),
                   Michael Roman (University of Leicester)

   Explanation: A mere 280 light-years from Earth, tidally locked,
   Jupiter-sized exoplanet WASP-43b orbits its parent star once every 0.8
   Earth days. That puts it about 2 million kilometers (less than 1/25th
   the orbital distance of Mercury) from a small, cool sun. Still, on a
   dayside always facing its parent star, temperatures approach a torrid
   2,500 degrees F as measured at infrared wavelengths by the MIRI
   instrument on board the James Webb Space Telescope. In this
   illustration of the hot exoplanet's orbit, Webb measurements also show
   nightside temperatures remain above 1,000 degrees F. That suggests that
   strong equatorial winds circulate the dayside atmospheric gases to the
   nightside before they can completely cool off. Exoplanet WASP-43b is
   now formally known as Astrolábos, and its K-type parent star has been
   christened Gnomon. Webb's infrared spectra indicate water vapor is
   present on the nightside as well as the dayside of the planet,
   providing information about cloud cover on Astrolábos.

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