What is the solar system?

The solar system is made up of the Sun and all things orbiting around it, including the nine major planets, several dozen satellites like our Moon, and all the asteroids and comets. Each one moves in a unique path around the Sun, and the Sun's force of gravity holds all the celestial bodies together. Our solar system is part of the Milky Way galaxy, a group of some hundred billion stars that are arranged in a vast disk-like shape held together by gravitational forces. Our solar system is located about halfway between one edge of the Milky Way and its center, so all the stars that we can see from Earth belong to our galaxy. But with giant telescopes, scientists have been able to observe many other galaxies in our universe; they believe there are 100 billion other galaxies.

For many years, the solar system included Pluto, for a total of nine planets. Pluto is now considered a planetoid and not a true planet. This drawing shows the arrangement of the planets, as well as how far each planet tilts on its axis.