Planet X

Cosma / Communication / Knowledge / Realm / Physical / Universe / Solar System / Scattered Disc / Planet X


More Support for Planet Nine (CalTech News)
Mike Brown (CalTech)


Planet X was a disproved hypothetical planet proposed in 1906 by Percival Lowell to have existed beyond the planet Neptune. Colloquially, and by extension, any hypothetical trans-Neptunian planet, in particular Planet Nine. — Wikipedia

Planet Nine is a hypothetical planet in the outer region of the Solar System. Its gravitational effects could explain the peculiar clustering of orbits for a group of extreme trans-Neptunian objects (ETNOs), bodies beyond Neptune that orbit the Sun at distances averaging more than 250 times that of the Earth. These ETNOs tend to make their closest approaches to the Sun in one sector, and their orbits are similarly tilted. These alignments suggest that an undiscovered planet may be shepherding the orbits of the most distant known Solar System objects. Nonetheless, some astronomers question the idea that the hypothetical planet exists and instead assert that the clustering of the ETNOs orbits is due to observational biases, resulting from the difficulty of discovering and tracking these objects during much of the year. — Wikipedia

Planet Nine (Wolfram Alpha)



Articles about Planet Nine (Big Think)




New Extremely Distant Solar System Object Found During Hunt for Planet X (Carnegie Institution for Science, AAAS EurekAlert)

The Super Earth that Came Home for Dinner (NASA/JPL)
Solar System Exploration: Planet X (NASA Science)




Mike Brown (CalTech)
Michael E. Brown (Wikipedia)

Konstantin Batygin (CalTech)
Konstantin Batygin (Wikipedia)


Subject: Planet X (Library Thing)

Subject: Planet X (Open Library)
Subject: Planet Nine (Open Library)

Subject: Planet Nine (WorldCat)




MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources



International Astronomical Union (IAU)
Asteroids & Remote Planets Section (British Astronomical Association)


Planet X (JSTOR)
Planet Nine (JSTOR)

Planet X (Astronomy Magazine)
Planet Nine (Astronomy Magazine)



Here are links to pages about closely related subjects.

Knowledge Realm


Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle

Universe (Astronomical Instrument)
Galaxy Milky Way, Andromeda
Planetary System Star, Brown Dwarf, Planet, Moon

Our Neighborhood
Solar System Sun
Terrestrial Planet Mercury, Venus, Earth (Moon), Mars
Asteroid Belt Ceres, Vesta
Jovian Planet Jupiter, Saturn, Uranus, Neptune
Trans-Neptunian Object
Kuiper Belt Pluto, Haumea, Makemake
Scattered Disc Eris, Sedna, Planet X
Oort Cloud Etc. Scholz’s Star
Small Body Comet, Centaur, Asteroid


1.   The resources on this page are are organized by a classification scheme developed exclusively for Cosma.