Seven Wonders of Asteroids, Comets, and Meteors

Seven Wonders of Asteroids, Comets, and Meteors — page 5
This photograph shows Ceres moving in orbit against a starry background 8 MORE LITTLE WORLDS Another tiny world was found the year after Ceres was discovered It is a little smaller than Ceres Astronomers named it Pallas They found two more over the next five years Both are smaller than either Ceres or Pallas Astraea the fifth to be discovered is only 100 miles 160 km wide These little worlds are so small that the astronomers first described them with the term minor planets Most people however know them as asteroids a word that means like stars Modern astronomers have listed several hundred thousand asteroids One estimate has one to two million asteroids orbiting between Mars and Jupiter This region has become known as the asteroid belt At least 98 percent of all known asteroids orbit there As many as four thousand of them are larger than 0 6 mile 1 km across This sounds like an awful lot of material But if every asteroid were to be combined into one big ball it would be less than 900 miles 1 448 km wide This is less than half the size of Earth's Moon Seven Wonders of Asteroids Comets and Meteors FACTS ABOUT Ceres THE LARGEST ASTEROID Ceres is the largest known asteroid It is 568 miles 914 km across almost twice the size of the next largest asteroid It is one fourth the size of all the asteroids in the entire asteroid belt combined It is larger than most of the moons of Saturn and Jupiter Diameter 590 miles 950 km Average distance from the Sun 277 million miles 446 million km Length of year the time it takes to orbit the Sun 1,680 days