Reference Work Entry

Encyclopedia of Astrobiology

pp 909-912

Late Heavy Bombardment

  • Philippe ClaeysAffiliated withEarth System Science, Vrije Universiteit Brussel Email author 
  • , Alessandro MorbidelliAffiliated withObservatoire de la Cote d’Azur


LHB; Lunar cataclysm


Asteroids, comets, gas planets, impact craters, impact process, meteorites, Moon, small bodies, solar system dynamics


The term Late Heavy Bombardment (or LHB) corresponds to an elevated frequency of collisions that affected the inner Solar System between 4.0 and 3.8 billion years ago. The Earth preserved no trace of these major impacts, but they can be found on the highly cratered surface of the Moon and other planets such as Mars, or in the age of the impact melt measured on meteorites originating from the asteroid belt. The LHB forms either the slowly decreasing tail end of planetary accretion or a localized cataclysmic event, perhaps triggered by a readjustment of the orbits of the large gas planets long after the formation of the Solar System.


Origin and Duration of the LHB

The current stratigraphic timescale places the Late Heavy Bombardment (LHB) period in the beginning of the Archean (in the Eoa ...

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