Could a lonely planet wander aimlessly through the restless galaxy change the subtle dance of gravity within our solar system ...

What is the difference between a moon and a planet? Trick question! According to scientific definitions, there often isn’t much of a difference at all. That might seem counterintuitive, but it’s true.

(CNN) — The search for an unknown planet in our solar system has inspired astronomers for more than a century. Now, a recent study suggests a potential new candidate, which the paper’s authors have ...

There are a couple of ways that scientists can date planets, so which planets formed first in our solar system?