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

What we know about the search for ‘Planet Nine’ in our solar system - The idea of a massive undiscovered planet has been around since before the discovery of Pluto in the 1930s ...

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

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

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

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 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 ...

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

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 ...

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.