Cosma / Communication / Knowledge / Realm / Physical / Universe / Solar System / Scattered Disc / Planet X
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Introduction1
TED (YouTube Channel)
TED (Official Website)
Encyclopedia
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
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Inspiration
Our Solar System Might Have Two Hidden Planets (SciShow, YouTube Video)
Study Suggests Planet 9 May Be Earth Like, Frozen and Much Closer (Anton Petrov, YouTube Video)
Are We Close to Finding Planet 9? (Astrum, YouTube Video)
Articles about Planet Nine (Big Think)
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Innovation
Science
The Super Earth that Came Home for Dinner (NASA/JPL)
Solar System Exploration: Planet X (NASA Science)
Planet X (Mike Brown’s Planets)
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Preservation
History
Planet X, Pluto, and NASA New Horizons (The History Guy, YouTube Video)
Mike Brown (CalTech)
Michael E. Brown (Wikipedia)
Konstantin Batygin (CalTech)
Konstantin Batygin (Wikipedia)
Library
Subject: Planet X (Library Thing)
Subject: Planet X (Open Library)
Subject: Planet Nine (Open Library)
Subject: Planet Nine (WorldCat)
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Participation
Education
MERLOT: Multimedia Educational Resource for Learning and Online Teaching
OER Commons: Open Educational Resources
Community
Organization
International Astronomical Union (IAU)
Asteroids & Remote Planets Section (British Astronomical Association)
News
Planet Nine (Nova Research Highlights, American Astronomical Society)
Planet X (Astronomy Magazine)
Planet Nine (Astronomy Magazine)
Planet X (JSTOR)
Planet Nine (JSTOR)
Planet X (Science Daily)
Planet Nine (Science Daily)
Planet X (Phys.org)
Planet Nine (Phys.org)
Recent News from Phys.org …
- Tabby's star may be orbited by a planetary-mass...on July 28, 2026 at 2:00 pm
By analyzing data from NASA's Transiting Exoplanet Survey Satellite (TESS) and conducting new radial velocity measurements, U.K. and French astronomers have found evidence that the mysterious Tabby's star may be orbited by an object about nine times more massive than Jupiter. The new findings are published on the preprint server arXiv.
- The surprising physics hiding in a single handful...on July 27, 2026 at 5:00 pm
Sand has a way of getting everywhere on a beach day—and for some, it can make or break the whole trip. There's the way it whips through the air just as sandwiches are being unwrapped, the way it turns blisteringly hot underfoot by midday, and the way it stubbornly clings to every piece of clothing.
- Underwater oxygen loss threatens earth's...on July 17, 2026 at 6:20 pm
A new review in Limnology and Oceanography led by scientists at UC San Diego's Scripps Institution of Oceanography warns that the rapid loss of oxygen from the ocean and other aquatic ecosystems is pushing Earth toward an "unsafe space," with consequences that could be irreversible on human timescales.
- Managing water with local wisdom and scienceon July 11, 2026 at 6:00 pm
Across a narrow watershed in Asakura, a rural city in Fukuoka Prefecture, centuries-old stone channels still guide water through fields and into the river below. Today, those same systems are the focus of researchers at Kyushu University's Watershed Systems Engineering Laboratory. One of their projects aims to restore abandoned rice fields to functioning wetlands and forest habitats.
- Mars express captures dozens of dust devils in...on July 5, 2026 at 5:00 pm
Dust devils are a regular feature on Mars. Just like those found on Earth, these mini whirlwinds form when parts of Mars are warmed by the sun, causing air above the surface to swirl upward and carry dust with it. But in Mars' lower gravity (38% that of Earth), these devils grow much larger, reaching up to 8 km (5 miles) in height and speeds of up to 45 meters per second (150 feet per second). They are also a major part of Mars' meteorological cycles, playing a key role in distributing dust […]
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Related
Here are links to pages about closely related subjects.
“Fundamentals”
Law (Constant) Relativity
Force Gravity, Electromagnetism (Light, Color)
Matter (Microscope) Molecule, Atom (Periodic Table), Particle
“Space”
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
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Notes
1. The resources on this page are are organized by a classification scheme developed exclusively for Cosma.





