                        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.

                                2025 April 6
    An astronaut is seen standing on the Moon next to an instrument with
   the lunar lander several meters in the distance. The dark of deep space
      covers the top of the frame. Please see the explanation for more
                            detailed information.

                       Moonquakes Surprisingly Common
                     Image Credit: NASA, Apollo 11 Crew

   Explanation: Why are there so many moonquakes? Analyses of seismometers
   left on the moon during the Apollo moon landings reveal a surprising
   number of moonquakes occurring within 100 kilometers of the surface. In
   fact, 62 moonquakes were detected in data recorded between 1972 and
   1977. Many of these moonquakes are not only strong enough to move
   furniture in a lunar apartment, but the stiff rock of the moon
   continues to vibrate for many minutes, significantly longer than the
   softer rock earthquakes on Earth. The cause of the moonquakes remains
   unknown, but a leading hypothesis include tidal gravity from -- and
   relative heating by -- our Earth. Regardless of the source, future moon
   dwellings need to be built to withstand the frequent shakings. Pictured
   here, Apollo 11 astronaut Buzz Aldrin stands beside a recently deployed
   lunar seismometer, looking back toward the lunar landing module.

                Explore Your Universe: Random APOD Generator
                     Tomorrow's picture: yes, flocculent
     __________________________________________________________________

       Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (UMCP)
            NASA Official: Amber Straughn Specific rights apply.
                  NASA Web Privacy, Accessibility, Notices;
                      A service of: ASD at NASA / GSFC,
                           NASA Science Activation
                             & Michigan Tech. U.

