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

(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 ...

Our solar system is a smashing success. A new study suggests that from its earliest period—even before the last of its nebular gas had been consumed—Earth's solar system and its planets looked more ...