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 ...

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 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 ...