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

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

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

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.

"But I just don't see a way that the solar system can exist the way it does without there being a Planet 9." As this year progresses, he says, the Rubin observatory will start building up a ...

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 outer solar system is theoretically predicted to harbor an undiscovered planet, often referred to as Planet Nine," the researchers wrote in their paper. "However, no observational evidence ...

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 ...

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.