NASA: National Aeronautics and Space Administration

  1. Question

    Is there any reason why we have an asteroid belt and not a 5th rocky planet?

    The gravitation force of giant planet Jupiter keeps the debris in the asteroid belt "stirred up" so that this material was not able to form a single planet between Mars and Jupiter. Over time, the asteroids collide and break up, thus reducing their size -- a process that continues today. David Morrison
    NAI Senior Scientist

    September 14, 2006

    1. Tell us what you think!


      It's your Astrobiology Program: please help us out by sending comments on what's here, and ideas for new features.

    Page Feedback

    Email (optional)
    Comment