Chasing Comets, Asteroids, and Mysterious Space Objects

Chasing Comets, Asteroids, and Mysterious Space Objects — page 3
CHAPTER 1 What Are Comets and Asteroids Earth is part of a solar system made up of objects that orbit the Sun These objects include eight planets Earth is one of them and millions of smaller objects Some travel close to the Sun while others stay in the outer reaches of our Solar System far from the Sun Many of these small objects are asteroids and comets Asteroids Asteroids are small lumps of rock and metals scarred with craters The largest is 329 miles 530 km across but others are the size of a house or smaller So far about 780,000 asteroids have been identified but there are many more Most asteroids lie in a belt between the orbits of Mars and Jupiter Asteroids dislodged from the asteroid belt travel through our Solar System on paths that sometimes bring them close to planets 4