Figure 9.35: Artist’s impression of the Moon during the Late Heavy Bombardment (LHB) (above) and today (below). The LHB is thought to have occurred approximately 4.1 to 3.9 billion years ago. During this interval, a large number of asteroids are believed to have collided with the early terrestrial planets in the inner solar system. The Moon was violently struck by numerous asteroids, creating large lunar plains (seas) and impact craters.
and gravitational instability. During this instability the fifth planet was scattered inward onto a Jupiter-crossing orbit and kicked out of the solar system following an encounter with King Jupiter. Before it was sent to a yet unknown location in our galaxy, however, the big planet might have created a state of chaos in the asteroid belt, causing a spike in the number of asteroids crossing the path of Earth and the Moon. Te Moon got a real makeover – and because there is no weather, the craters have not eroded, giving it the face that we see today.
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9.2.5 The Moons of Mars
Mars has two moons, Phobos and Deimos, named after the horses that pulled the chariot of the Greek war god Ares, the counterpart to the Roman war god Mars. Phobos means fear (as in phobia), while Deimos means flight (especially in the sense of fleeing after a defeat). Te origin of Phobos and Deimos is still an open question. Since the moons appear to have surface materials similar to many asteroids in the outer asteroid belt, most scientists believe that Phobos and Deimos are captured
