  The habitability of planets is strongly affected by impacts from comets and
asteroids. Indications from the ages of Moon rocks suggest that the inner Solar
System experienced an increased rate of impacts roughly 3.8 Gya known as the
Late Heavy Bombardment (LHB). Here we develop a model of how the Solar System
would have appeared to a distant observer during its history based on the Nice
model of Gomes et al. (2005). We compare our results with observed debris
discs. We show that the Solar System would have been amongst the brightest of
these systems before the LHB. Comparison with the statistics of debris disc
evolution shows that such heavy bombardment events must be rare occurring
around less than 12% of Sun-like stars.
