A newly discovered object orbiting far beyond Neptune has its closest approach to the Sun pointed in the opposite direction from every other known body like it, weakening one of the central ...

It's an evocative idea that has long bedeviled scientists: a huge and mysterious planet is lurking in the darkness at the edge of our solar system, evading all our efforts to spot it. Some astronomers ...

Growing up, I was taught that there were nine planets in the solar system. That all changed in 2006, when the International Astronomical Union voted to demote Pluto’s status to that of dwarf planet.

After studying thousands of computer simulations of the solar system, researchers at Rice University and the Planetary Science Institute think there’s a 40% chance an elusive “Planet Nine” or “Planet ...

Mike Brown is convinced that beyond Neptune, at the far reaches of our solar system, there's an unseen giant planet. "This is the 5th largest planet in our solar system, lurking out there, waiting to ...

Add Yahoo as a preferred source to see more of our stories on Google. Planet Nine is a hypothesized massive planet, first proposed in 2014, that is speculated to orbit far out in the solar system. It ...

An artist's illustration of a possible ninth planet in our solar system, hovering at the edge of our solar system. Neptune's orbit is shown as a bright ring around the Sun. Scientists in Taiwan ...

In the cold, dark outskirts of planetary systems far beyond the reach of the known planets, mysterious gas giants and planetary masses silently orbit their stars—sometimes thousands of astronomical ...

Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more. Our solar system ...

Is there a massive undiscovered planet on the outer reaches of the Solar System? The idea has been around since before the discovery of Pluto in the 1930s. Labelled as planet X, prominent astronomers ...