Astronomers propose a new hypothetical planet, Planet Y, beyond Neptune, based on observed orbital anomalies in the Kuiper ...

A new study suggests the existence of Planet Y. This hidden planet may be affecting the Kuiper Belt. The gravity of Planet Y could be causing a tilt in the orbits of some icy objects. Researchers ...

For years, astronomers have searched the outer reaches of our solar system for Planet 9, a theoretical planet that could ...

New discoveries of objects in the Kuiper Belt have also presented challenges for the Planet Nine theory. The latest is known ...

Another mystery is how Planet Nine, if it is real, ended up on an orbit that potentially brings it as close as 280 AU and as distant as 1,120 AU, which is far beyond the realm of the other planets.

Planet Nine's composition is probably "most like Neptune," due to its distance from the sun, Brown said. "That would put its diameter at something like two times the width of Earth," he added.

Astronomers have picked up evidence of an Earth-sized world, distinct from the previously hypothesised Planet Nine and Planet ...

If their calculations serve them correctly, Planet Nine would have a mass that is about 1.5 to 3 times that of Earth, at 500 times the distance between our home and the sun. Caltech researchers in ...

A hypothetical planet that has been described as "the solar system's missing link," Planet Nine (also known as Planet X) has been part of the lexicon for several years, first mentioned in 2014.

Artist's illustration of Planet Nine, a world about 10 times more massive than Earth that may lie undiscovered in the far outer solar system. (Image credit: Caltech/R. Hurt (IPAC)) ...

Based on complex simulations, the team says there's around a 40 per cent chance that a Planet Nine-like object is hiding in our solar system. And if it does exist, it could be discovered using the ...

Planet 9 and the Weird KBO Orbits The idea of a ninth planet existing at the edge of the solar system, far beyond Neptune, was put forward in 2014.