Asteroids vs Comets The Solar System is full of fascinating objects beyond the eight major planets. Among these objects, asteroids and comets are two of the most interesting and mysterious bodies. They are often described as “leftovers” from the formation of the Solar System about 4.6 billion years ago. While they may appear similar at first glance—both being relatively small objects that orbit the Sun—they are actually very different in terms of composition, structure, origin, and behavior.