Aug. 25, 2007 The traditional belief that Jupiter acts as a
celestial shield, deflecting asteroids and comets away from the
inner Solar System, has been challenged by the first in a series
of studies evaluating the impact risk to the Earth posed by
different groups of object. On Friday 24th August at the
European Planetary Science Congress in Potsdam, Dr Jonathan
Horner presented a study of the impact hazard posed to Earth by
the Centaurs, the parent population of the Jupiter Family of
comets (JFCs). The results show that the presence of a Jupiter-
like planet in the Solar System does not necessarily lead to a
lower impact rate at the Earth. Dr Horner, from the UK's Open
University (OU), said, "The idea that a Jupiter-like planet
plays an important role in lessening the impact risk on
potentially habitable planets is a common belief but there has
only really been one study done on this in the past, which
looked at the hazard due to the Long Period Comets. We are
carrying out an ongoing series of studies of the