Researchers say they found a curious dot on infrared images taken 23 years apart that seems to be moving in a manner ...

For years, astronomers have toyed with the idea that the Sun hides an extra planet so distant and dim that even the best ...

Our solar system may have a ninth planet after all, following the declassification of Pluto nearly two decades ago, ...

A ninth planet the size of Neptune may be hidden in the far reaches of the solar system, but the evidence has left some experts skeptical.

Over millions of years, these objects grew larger, sweeping up material in their orbits and becoming the planets we know today. This model of solar system formation is known as the nebular hypothesis.

What just happened? A newly identified object spotted in two infrared sky surveys may be the most substantial evidence for the elusive Planet Nine – a potential Neptune-sized world orbiting ...

If the object really is Planet Nine, it would be larger than Neptune ... The possibility of additional planets in our solar system has been proposed many times, going under names such as "Planet ...

The existence of Planet Nine — or any other undiscovered ninth planet in our solar system — will likely remain a contentious subject for now. However, 2025 could prove to be the beginning of ...

For nearly a decade, scientists have been on the hunt for Planet Nine – a hypothetical celestial object on the edge of our Solar System. Now, astronomers claim to have discovered this ninth ...

While scientists are still trying to confirm Planet Nine's existence, NASA says proving that this ice giant is real would help astronomers explain several mysteries within our solar system.