There are eight official planets (sorry, Pluto) in our solar system: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and ...

A few decades ago, the Solar System had nine planets, but in 2006 the International Astronomical Union reclassified Pluto as ...

The newcomer replacing Pluto presently goes by “Planet Nine.” If and when it finally shows up, it will get the honor of a ...

If Brown’s hidden world is real, Rubin will almost certainly find it or strong indirect evidence that it exists. “In the ...

“Because Pluto is rotating rapidly prior to the collision, and because Charon lies mostly outside of their corotation zone, ...

New models reveal Pluto and Charon may have spent some of their early history locked together in an embrace after a grazing ...

The potential discovery of a large planet beyond Neptune’s orbit could change everything we know about the Solar System.

An curved arrow pointing right. Astronomers say they've discovered a ninth planet 200 times farther from the Sun than Earth. Produced by Emmanuel Ocbazghi. Original Reporting by Jessica Orwig.

Opinions expressed by Forbes Contributors are their own. Jamie Carter is an award-winning reporter who covers the night sky. Computer simulations suggest that there is an undiscovered Earth-like ...

She, like her fellow soldiers, do not remember anything about the Ninth Planet - their real memory has been erased, and false memories have been implanted instead.