Planet Nine

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, 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 this conclusion 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.

Read more in the app

A 'Planet Nine' far from Earth could explain the odd behavior of icy bodies beyond Neptune

Elusive Planet Nine could be surrounded by hot moons, and that's how we'd find it

But Wait: What if The Hypothetical Planet Nine Has Moons?

Astronomers Still Find No Signs of Planet Nine After Scanning 87% of the Southern Sky

Surprise! We Still Haven't Found Planet Nine

Planet Nine is still missing in action after survey of 87% of the Southern Sky

Searching for Planet Nine: What Is Lurking in the Outer Reaches of Our Solar System?

If Planet Nine exists, why has no one seen it? - BBC Future

An astronomer claims he has found the fabled Planet Nine after spending thousands of hours looking through 38-year-old satellite data, and he wants others to go hunting for this hypothetical planet in the far reaches of the Solar System

Mysterious Object Glimpsed Decades Ago Might Have Actually Been Planet Nine

Enigmatic Planet Nine may have been seen by telescope in the 1980s

[2108.09868] The orbit of Planet Nine

Astronomers Create 'Treasure Map' to Find Proposed Planet Nine

The orbit of Planet Nine

Want to find Planet Nine? Here's a treasure map.

Planet Nine may be a black hole the size of a baseball

Blast off to Planet Nine with 'The Crew' space card game for 31% off this Prime Day

Dozens of NASA scientists will take part in an event this weekend introducing citizen science projects that help advance the space agency’s research. Participants hunt exoplanets, asteroids, comets, aurorae and even Planet Nine.

If Planet Nine Is Out There, It May Not Be Where We Think

What if Planet Nine is a baby black hole?