Page 50 - Curriculum Visions Dynamic Book

Craters on the Moon
Craters are one of the most extensive features of the Moon’s surface. They were made by the impact of meteorites.
Meteorites can strike the surface of the Moon more forcefully than the surface of the Earth because there is no thick atmosphere to slow them down. They also survive intact because there are no weathering processes on the Moon like those on the Earth (temperature, wind, water, and ice).
As each meteorite strikes the surface, the collision not only throws out huge amounts of material, but very high temperatures are created, which change the nature of many of the rocks.
Thus molten rocks are splattered out of the crater, together with solid material that has shattered rather than melted.
Larger craters are very deep as well as wide. One, Aristarchus, is about 40 kilometres in diametre and 4 kilometres deep.
This ancient impact created a great pit, but at the same time pushed material away so that a tall rim developed. Such rims are tall enough to be called mountains.
crater A deep bowl-shaped depression in the surface of a body formed by the high- speed impact of another, smaller body.
gravity The force of attraction between bodies. The larger an object, the more its gravitational pull on other objects.
meteorite A meteor that reaches the Earth’s surface.
ray A line across the surface of a planet or moon made by material from a crater being flung across the surface.
weathering The breaking down of a rock, perhaps by water, ice, or repeated heating and cooling.
 An artist’s impression of a meteorite hitting the surface of the Moon and creating a crater, together with the debris that forms rays.
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