Besides the sun, 8 planets and their moons, our Solar System contains billions of other objects and extends far beyond the outermost planets. There are several hundred thousand asteroids revolving around the Sun. Most have orbits between Mars and Jupiter. Also, in addition to the more than 800 comets we have recorded passing through the inner part of the solar system, there are billions more lying in the area surrounding the solar system. They are in the disk of debris known as the Kuiper belt and the cloud of comets known as the Oort cloud.
Next, to a smaller scale, there are countless meteoroids (some of which include cometary debris and fragments from the collision of larger bodies), some of which approach Earth's orbit closely enough to be known as near Earth objects. Finally, billions of objects (many the size of a speck of dust) cross through our atmosphere as meteors or micrometeoroids each day, usually completely unnoticed.
See also Solar System Origin.