                        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.

                                2022 April 17

                             Shuttle Over Earth
                   Image Credit: NASA, Expedition 22 Crew

   Explanation: What's that approaching? Astronauts on board the
   International Space Station in 2010 first saw it far in the distance.
   Soon it enlarged to become a dark silhouette. As it came even closer,
   the silhouette appeared to be a spaceship. Finally, the object revealed
   itself to be the Space Shuttle Endeavour, and it soon docked as
   expected with the Earth-orbiting space station. Pictured here,
   Endeavour was imaged near Earth's horizon as it approached, where
   several layers of the Earth's atmosphere were visible. Directly behind
   the shuttle is the mesosphere, which appears blue. The atmospheric
   layer that appears white is the stratosphere, while the orange layer is
   Earth's Troposphere. Together, these thin layers of air -- collectively
   spanning less than 2 percent of Earth's radius -- sustain us all in
   many ways, including providing oxygen to breath and a barrier to
   dangerous radiations from space.

                      Coming up Friday: Earth Day 2022
                       Tomorrow's picture: steppe sky
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Phillip Newman Specific rights apply.
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                      A service of: ASD at NASA / GSFC
                             & Michigan Tech. U.

