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

Astronomers have long speculated about the existence of a mysterious planet lurking far beyond Neptune, a world several times ...

"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 ...

A tiny object far beyond Pluto, newly discovered by the Subaru Telescope, could reshape our understanding of the early Solar System. Named 2023 KQ14, this rare “sednoid” follows an unusual orbit that ...

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 ...

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

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 ...

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.

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.