Final answer:
Astronomers have discovered a wide variety of planetary systems that are different from our own solar system.
Step-by-step explanation:
One of the many things astronomers have discovered by studying other planetary systems is the existence of a wide variety of planetary systems that are different from our own solar system. For example, astronomers have found exoplanetary systems with planets that orbit close double stars, planets that are intermediate in size between terrestrial and giant planets known as superearths, and even systems with giant planets close to the star, reversing the order seen in our system.