A newly discovered warp in the outer Solar System may have been created by a small, rocky world, much closer to the Sun than ...

After the discovery of Neptune in 1846, astronomers kept searching for another solar system planet, which in the early 20th ...

A leading scientist has told Newsweek about new evidence supporting the existence of a secret ninth planet lurking at the edge of our solar system. This hypothetical extra planet, often referred to as ...

A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth ...

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 ...

Researchers at the California Institute of Technology (Caltech) have found new evidence that further suggests there is a ninth planet in our solar system. Nicknamed "Planet Nine," researchers said ...

The mysterious Planet Nine may have up to 20 moons that could be superheated by the hypothetical planet's gravitational pull, making them easy to spot. When you purchase through links on our site, we ...

A possible new dwarf planet has been discovered at the edge of our solar system, so far-flung that it takes around 25,000 years to complete one orbit around the sun. The object, known as 2017 OF201, ...

Earlier this year scientists presented evidence for Planet Nine, a Neptune-mass planet in an elliptical orbit 10 times farther from our Sun than Pluto. Since then theorists have puzzled over how this ...

Astronomers have been scouring the outer solar system for signs of a hypothetical ninth planet for almost a decade, without success. However, we may finally be on the cusp of finding it, experts say.

Astronomers know very little about the far outer Solar System — beyond Neptune, Pluto, and the far-flung Kuiper belt. For the past seven years, some scientists have observed certain gravitational ...

For many years, there have been theories circulating about Planet Nine, a mysterious planet that orbits the Sun once every 10,000 or 20,000 years, and now physicists are suggesting it may not even be ...