                        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.

                               2023 January 1
    The featured image shows several streaks on a dark background with a
     pale blue dot in one of the streaks. Please see the explanation for
                         more detailed information.

                    The Largest Rock in our Solar System
                  Image Credit: NASA, Voyager 1 spacecraft

   Explanation: There, that dot on the right, that's the largest rock
   known in our Solar System. It is larger than every known asteroid,
   moon, and comet nucleus. It is larger than any other local rocky
   planet. This rock is so large its gravity makes it into a large ball
   that holds heavy gases near its surface. (It used to be the largest
   known rock of any type until the recent discoveries of large dense
   planets orbiting other stars.) The Voyager 1 spacecraft took the
   featured picture -- famously called Pale Blue Dot -- of this giant
   space rock in 1990 from the outer Solar System. Today, this rock starts
   another orbit around its parent star, for roughly the 5 billionth time,
   spinning over 350 times during each trip. Happy Gregorian Calendar New
   Year to all inhabitants of this rock we call Earth.

                      Tomorrow's picture: planets align
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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,
                           NASA Science Activation
                             & Michigan Tech. U.

