A new study has proposed the existence of Planet Y, an alternative Planet Nine candidate that is smaller and closer to Earth than the hypothetical Planet X, which astronomers have been hunting for ...

Finding Earth-like planets orbiting sun-like stars and identifying signs of life such as oxygen or water is a major goal in ...

There may be a warp in the Kuiper Belt, possibly caused by “Planet Y” — a Mercury-to-Earth-sized world that orbits the sun way beyond the orbit of Neptune. Is there a mysterious “Planet Y” orbiting ...

Astronomers have discovered what appears to be an exoplanet that could be a distant Earthly paradise. Or it could be a frigid realm even chillier than Mars, incapable of supporting life. The margins ...

Astronomers believe they have uncovered evidence of a previously unknown ninth planet lurking in the not-too-distant reaches of the solar system. This hypothetical world, dubbed "Planet Y," could be ...