MOFFETT FIELD, Calif., Feb. 28 (UPI) -- The moon, hit by asteroids throughout its lifetime, saw a strong increase in the energy and speed of incoming rocks 4 billion years ago, U.S. researchers say.
Scientists the NASA Lunar Science Institute in California said the history of crater formation on the moon, analyzed using digital maps, reveals a significant rise in the velocity and energy of the cosmic onslaught during a period dubbed the "lunar cataclysm" around 4 billion years ago, SPACE.com reported Tuesday.
Researchers said it was possible the timing of this change could coincide with disturbances in the solar system's main asteroid belt following changes in the movement of the outer planets.
The speeds of incoming asteroids during the lunar cataclysm were likely increased by the movement of Jupiter and the other outer solar system planets, they said.
"It is fascinating that the surface of our own moon records evidence of orbital changes in Jupiter and Saturn that took place so long ago," Yvonne Pendleton, director of the institute, said in a statement.
The reorganization of the outer planets could have dislodged objects in the main asteroid belt and thrown them into the inner solar system, researchers said.