                        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.

                                2024 March 22

                           Phobos: Moon over Mars
    Image Credit: NASA, ESA, Zolt Levay (STScI) - Acknowledgment: J.Bell
                           (ASU) and M.Wolff (SSI)

   Explanation: A tiny moon with a scary name, Phobos emerges from behind
   the Red Planet in this timelapse sequence from the Earth-orbiting
   Hubble Space Telescope. Over 22 minutes the 13 separate exposures were
   captured near the 2016 closest approach of Mars to planet Earth.
   Martians have to look to the west to watch Phobos rise, though. The
   small moon is closer to its parent planet than any other moon in the
   Solar System, about 3,700 miles (6,000 kilometers) above the Martian
   surface. It completes one orbit in just 7 hours and 39 minutes. That's
   faster than a Mars rotation, which corresponds to about 24 hours and 40
   minutes. So on Mars, Phobos can be seen to rise above the western
   horizon 3 times a day. Still, Phobos is doomed.

                   Tomorrow's picture: Ares 3 Landing Site
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       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
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                           NASA Science Activation
                             & Michigan Tech. U.

