Which sentence states a fact?

 - Earth is the most important planet in the solar system.
 - Our solar system contains eight planets.
The second sentence states a fact.
Our solar system contains eight planets.
It can be proved by checking a drawing of the solar system.
The first sentence states an opinion.
Earth is the most important planet in the solar system.
Most important shows what a person believes, thinks, or feels. Another person might have a different opinion about which planet is the most important.