KULVINDER SINGH CHADHA Posted: 26 February, 2009 The migration
of Jupiter and Saturn could have turned asteroids in the early
Solar System into missiles that pelted the inner planets. This
is the interpretation of a team of scientists who discovered
that asteroids in the Asteroid Belt are missing. The team, from
the University of Arizona looked at the distribution of all
asteroids over 30 kilometres in diameter. It is well known that
the gravitational effect of Jupiter and Saturn creates regions
in the Asteroid Belt (a ring of rocky bodies lying between the
orbits of Mars and Jupiter) where objects can’t stay in stable
orbits around the Sun. Over time, these objects leave the
regions, creating what are known as the Kirkwood gaps
(discovered and explained in 1857 by the American astronomer
Daniel Kirkwood). Graduate Student David Minton says, “What we
wanted to know was, how much of the structure of the Asteroid
Belt could be explained simply by the gravitational effects of
the giant planets, [such as] the Kir