A growing body of evidence indicates that early Earth experienced a period of cataclysmic bombardment by comets and/or asteroids.
Scientists refer to this period as the Late Heavy Bombardment (LHB). Any impactor larger than a few hundred yards in diameter would unleash a destructive blast at least ten times larger than the simultaneous detonation of the world’s entire nuclear arsenal. Many of the objects hitting Earth during the LHB were miles wide and surely sterilized the surface of the planet.
In the past year, scientists found evidence for one likely cause of the LHB by looking at the distribution of asteroids in the main asteroid belt. Additionally, computer simulations indicate that the LHB might not have been as destructive as initially thought. As I discussed in a previous TNRTB, these discoveries highlight how catastrophic episodes seem to actually prepare the way for future life rather than destroy it.