Astronomy Picture of the Day

   [1]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 September 17
    [2]See Explanation. Clicking on the picture will download the highest
                        resolution version available.

                 Water Vapor Discovered on Distant Exoplanet
       Illustration Credit: [3]ESA, [4]NASA, [5]Hubble; Artist: [6]M.
                                 Kornmesser

   Explanation: Where else might life exist? One of humanity's great
   outstanding questions, locating planets where extrasolar life might
   survive took a step forward recently with the discovery of a
   significant amount of water vapor in the atmosphere of distant
   exoplanet [7]K2-18b. The planet and it parent star, [8]K2-18, lie about
   124 light years away toward the constellation of the [9]Lion ([10]Leo).
   The [11]exoplanet is significantly larger and more massive than our
   Earth, but orbits in the [12]habitable zone of its home star. K2-18,
   although more red than our Sun, shines in [13]K2-18b's sky with a
   brightness similar to the [14]Sun in Earth's sky. The [15]discovery was
   made in data from three space telescopes: [16]Hubble, [17]Spitzer, and
   [18]Kepler, by noting the absorption of water-vapor colors when the
   [19]planet moved in front of the star. The [20]featured illustration
   imagines exoplanet K2-18b on the right, its parent [21]red dwarf star
   K2-18 on the left, and an unconfirmed sister planet between them.

                      Tomorrow's picture: lightning up
     __________________________________________________________________

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    Authors & editors: [33]Robert Nemiroff ([34]MTU) & [35]Jerry Bonnell
                                 ([36]UMCP)
          NASA Official: Phillip Newman [37]Specific rights apply.
              [38]NASA Web Privacy Policy and Important Notices
                A service of: [39]ASD at [40]NASA / [41]GSFC
                           & [42]Michigan Tech. U.

References

   1. https://apod.nasa.gov/apod/archivepix.html
   2. https://apod.nasa.gov/apod/image/1909/K218b_ESAKornmesser_6000.jpg
   3. https://www.esa.int/
   4. https://www.nasa.gov/
   5. https://www.spacetelescope.org/
   6. https://www.spacetelescope.org/projects/anniversary/production_team/
   7. https://en.wikipedia.org/wiki/K2-18b
   8. https://en.wikipedia.org/wiki/K2-18
   9. http://ae01.alicdn.com/kf/HTB1wvWmKxSYBuNjSspjq6x73VXay.jpg_q50.jpg
  10. https://en.wikipedia.org/wiki/Leo_(constellation)
  11. https://apod.nasa.gov/apod/ap190710.html
  12. https://www.nasa.gov/ames/kepler/habitable-zones-of-different-stars
  13. https://www.spacetelescope.org/videos/heic1916a/
  14. https://apod.nasa.gov/apod/ap150512.html
  15. https://nouvelles.umontreal.ca/en/article/2019/09/11/water-detected-on-an-exoplanet-located-in-its-star-s-habitable-zone/
  16. https://hubblesite.org/mission-and-telescope/the-telescope
  17. http://www.spitzer.caltech.edu/info/277-Fast-Facts
  18. https://www.nasa.gov/mission_pages/kepler/spacecraft/index.html
  19. http://www.planetary.org/explore/space-topics/exoplanets/transit-photometry.html
  20. https://www.spacetelescope.org/images/heic1916a/
  21. https://en.wikipedia.org/wiki/Red_dwarf
  22. https://apod.nasa.gov/apod/ap190916.html
  23. https://apod.nasa.gov/apod/archivepix.html
  24. https://apod.nasa.gov/apod/lib/apsubmit2015.html
  25. https://apod.nasa.gov/apod/lib/aptree.html
  26. https://antwrp.gsfc.nasa.gov/cgi-bin/apod/apod_search
  27. https://apod.nasa.gov/apod/calendar/allyears.html
  28. https://apod.nasa.gov/apod.rss
  29. https://apod.nasa.gov/apod/lib/edlinks.html
  30. https://apod.nasa.gov/apod/lib/about_apod.html
  31. http://asterisk.apod.com/discuss_apod.php?date=190917
  32. https://apod.nasa.gov/apod/ap190918.html
  33. http://www.phy.mtu.edu/faculty/Nemiroff.html
  34. http://www.phy.mtu.edu/
  35. https://antwrp.gsfc.nasa.gov/htmltest/jbonnell/www/bonnell.html
  36. http://www.astro.umd.edu/
  37. https://apod.nasa.gov/apod/lib/about_apod.html#srapply
  38. https://www.nasa.gov/about/highlights/HP_Privacy.html
  39. https://astrophysics.gsfc.nasa.gov/
  40. https://www.nasa.gov/
  41. https://www.nasa.gov/centers/goddard/
  42. http://www.mtu.edu/