There could be a ninth planet in our Solar System after all - and no, it's not Pluto. Instead, it's the theoretical Planet X, also called Planet Nine, a wide-orbit planet that would circle the Sun ...

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 dubbed ...

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth than the hypothetical Planet X, which astronomers have been hunting for ...