                        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 February 1

                              Moon Phases 2022
    Video Credit: Data: Lunar Reconnaissance Orbiter ; Animation: NASA's
                      Scientific Visualization Studio;
       Music: Build the Future (Universal Production Music), Alexander
                                  Hitchens

   Explanation: What will the Moon phase be on your birthday this year? It
   is hard to predict because the Moon's appearance changes nightly. As
   the Moon orbits the Earth, the half illuminated by the Sun first
   becomes increasingly visible, then decreasingly visible. The featured
   video animates images and altitude data taken by NASA's Moon-orbiting
   Lunar Reconnaissance Orbiter to show all 12 lunations that appear this
   year, 2022 -- as seen from Earth's northern (southern) hemisphere. A
   single lunation describes one full cycle of our Moon, including all of
   its phases. A full lunation takes about 29.5 days, just under a month
   (moon-th). As each lunation progresses, sunlight reflects from the Moon
   at different angles, and so illuminates different features differently.
   During all of this, of course, the Moon always keeps the same face
   toward the Earth. What is less apparent night-to-night is that the
   Moon's apparent size changes slightly, and that a slight wobble called
   a libration occurs as the Moon progresses along its elliptical orbit.

                 Tomorrow's picture: to circle a dying star
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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.

