Mercury has long baffled astronomers because it defies much of what we know about planet formation. A new space mission ...

A newly discovered warp in the outer Solar System may have been created by a small, rocky world, much closer to the Sun than the hypothesized Planet Nine. According to a new measurement of the Kuiper ...

An exoplanet is what we call planets that exist outside of our own solar system. The first one was discovered in 1992, but as we get more powerful and precise telescopes and instruments, scientists ...