The Solar System - Grades: 1–2, 3–5 Earth is one of nine known
planets that go around our star, the sun. Other objects go
around the sun, too — large chunks of rocks called asteroids,
balls of ice called comets, and dust particles. All of these
belong to our solar system. Our solar system is in the Milky Way
galaxy. There are millions of other systems in this galaxy. The
Milky Way galaxy is part of the universe. From Earth, the other
planets look flat. But they are really shaped more like balls.
Planets move in two ways. Every planet turns around and around
like a spinning top. This movement is called rotating. As each
planet rotates, it also follows a path around the sun. The path
is called an orbit. We say the planet orbits (revolves around)
the sun. Something else makes our solar system work the way it
does. It is a force called gravity. Gravity — the Greatest Force
Of All When you hold a pencil in your hand and let it go, it
falls to the ground. Why doesn't it float in the air? A great
scientist, Albert E