Meaning of late heavy bombardment in English:

late heavy bombardment

noun

Astronomy
  • An event suggested as having occurred during the early history of the solar system, when an exceptionally large number of asteroids may have collided with the terrestrial planets as they were being formed.

    This event is dated to about 4 billion years ago, a time late in the accretion period of the solar system (though not in the history of the solar system as a whole).

Origin

1970s.