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 …
- A rush for critical minerals echoes oil...on April 29, 2026 at 4:10 am
Mining critical minerals such as lithium and cobalt fuels the "green" energy and digital transitions essential to meeting climate goals. But building the technologies that enable a sustainable future is generating severe, hidden environmental and health crises that the world is failing to track or address, warns a new report by the United Nations University Institute for Water, Environment and Health (UNU-INWEH), known as the UN's Think Tank on Water.
- Antarctica's ice shelves are vulnerable to...on April 28, 2026 at 11:27 am
A rare dataset collected by instruments at the point where Antarctica's largest ice shelf begins to float reveals ocean processes that drive melting at this critical part of the continent.
- Mining the solar system to build a new worldon April 27, 2026 at 3:40 pm
I watched Armageddon again fairly recently with Bruce Willis, oil drillers in space and an asteroid the size of Texas bearing down on Earth. Buried beneath the Hollywood chaos is a genuinely interesting question: What exactly could we do with an asteroid if we got our hands on one? As it turns out, the answer has nothing to do with blowing it up, sorry Bruce, but everything to do with building a new world.
- Stellar flares may expand habitable zones around...on April 22, 2026 at 11:00 pm
The search for life beyond Earth has traditionally focused on exoplanets orbiting sun-like stars, which is a G-type star. However, low-mass stars, which are designated as K-type and M-type stars, have rapidly become a target for astrobiology, primarily due to their much longer lifetimes. This also means the habitable zone (HZ), which is the distance from a star where liquid water could exist, is much smaller than our solar system's HZ, and is referred to as the liquid water habitable zone […]
- Boots on the moon and beyond. Where next after...on April 16, 2026 at 5:40 pm
It is tempting to view the Artemis II splashdown as the exclamation point on a successful lunar mission. And from launch to completion, it was indeed a textbook voyage of discovery for four astronauts, shared with enthralled millions watching across the globe.
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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.





