
Many people think of space as being empty, but that isn't true. In addition to stars, planets, and moons, there are asteroids and comets. Readers learn that asteroids are rocks that orbit the sun. Comets are chunks of ice and dust that form on the edges of the solar system. This...

Many people think of space as being empty, but that isn't true. In addition to stars, planets, and moons, there are asteroids and comets. Readers learn that asteroids are rocks that orbit the sun. Comets are chunks of ice and dust that form on the edges of the solar system. This...