Is there a massive undiscovered planet on the outer reaches of the solar system? The idea has been around since before the ...

"It is possible that a planet once existed in the solar system but was later ejected, causing the unusual orbits we see today ...

Researchers use the Subaru Telescope in Hawaii to find a small object on the outer edge of the Solar System. Nicknamed ...

Astronomers have found 2023 KQ14, nicknamed Ammonite, a rare sednoid with a unique orbit that challenges the Planet Nine ...

A newly discovered dwarf planet called 'Ammonite' (2023 KQ14) has been spotted in the outer solar system, and it could be ...

For reference, Pluto’s average distance from the Sun is about 40 AU, so 2023 KQ14 is quite distant. At 23.4 billion miles (37 ...

Theories about Planet Nine have been swirling for years, but this newly discovery planet might put those theories to bed for good.

Planet Fitness will join a revitalized shopping center that recently added Aldi and Tesla. Leaving its former space makes ...

Planet Nine should appear stationary over the course of a single day but show detectable movement over months.

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.

Planet Nine (illustrated) is a hypothetical giant planet hiding at the solar system’s edge — but new work suggests the evidence for it is a mirage. ESA/Hubble, M. Kornmesser By Lisa Grossman ...