Planet X

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

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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)

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