Astronomers are closing in on one of the most tantalizing possibilities in planetary science, evidence that a previously unknown world may be lurking in the outer reaches of the solar system. The ...

Astronomers studying the Kuiper Belt have detected a strange distortion that could point to an unknown planet lurking far beyond Neptune.

Astronomers have discovered thousands of planets beyond our solar system, but finding them is incredibly difficult. Unlike ...

LONDON — A long-lost planet that helped create the Moon may have formed much closer to the Sun than scientists once thought, according to new research. Scientists have discovered that Theia, the ...

Astronomers have uncovered evidence of a spectacular collision of two planets within the confines of a faraway solar system, providing us with a rare .