First, students will first simulate the effects of collision between asteroids, and describe the resulting size distribution. Next, using images of Jupiter's four largest moons obtained by NASA's Galileo spacecraft, students will investigate crater densities and size distributions, and interpret those in terms of relative surface ages and how the craters might have been formed. The Earth and Moon have been continuously pelted by asteroids and comets ever since their formation. Just look at the Moon through a small telescope or a good pair of binoculars, and you will see that its surface is covered by craters. It is now believed that a large impact near the Yucatan Peninsula of Mexico, called the Chicxulub crater, caused the dinosaur extinction 65 million years ago.
Craters are one of the most interesting and important types of surface features in the solar system.
They are found on almost all the solid planets, satellites, and asteroids, but not on gas giants like Jupiter and Saturn since there is no solid surface to preserve them. Preserved craters are also fairly rare on Earth, but only because weathering, erosion, and other geological processes have removed them. Scientists believe that most craters are formed by the impact of asteroids and comets, but these aren't the only ways that large circular depressions can be made on a surface. For example, some might actually be calderas, created by erupting volcanoes. The asteroid belt is a region of small planetesimals between the orbits of Mars and Jupiter.