Planet Nine

This object is hypothetical.

This object is hypothetical, and was proposed to explain a phenomenon or occurrence. Note that such object has not been discovered or observed.

This page is about Planet Nine. You may be looking for Nibiru, Tyche, or the Fifth Giant .

Planet Nine
Artist’s impression of what Planet Nine could look like. A dark, distant world with barely any of the Sun's light reaching it.
Discovery
Discovered By	Nobody (Existence hasn't been confirmed)
Discovery Data	Yet to be discovered
Orbital Characteristics
Apoapsis	~560 AU
Periapsis	~340 AU
Semi-major Axis	~460 AU ~290 AU
Eccentricity	~0.2 – 0.5 ~0.29
Orbital Period (sidereal)	~9,900 Years
Inclination	16° 6.8°
Satellites	???
Physical Characteristics
Dimensions	~40,000 Km
Mean Radius	~20,000 Km
Circumference (meridional)	~125,663.7 Km
Surface Area (total)	~1,256,637,061 Km2
Mass	6.2 - 4.4 Earth Masses
Apparent Magnitude	~21

The orbit of 2015 KG₁₆₃ (right side, in orange) and other extreme detached objects, along with the hypothetical Planet Nine's orbit on the right

Planet Nine is a hypothetical planet hypothesized to exist in the outermost edges of the Solar System, possibly in the Oort Cloud. It is thought to be about 40,000 kilometers in diameter,^{(Citation needed)} probably larger than Earth but smaller than Neptune. It is likely composed of the same materials as the ice giants, like hydrogen, helium, methane, water, and ammonia. It is also likely to have a simple ring system similar to that of Neptune's. Because of its distance from the Sun, it is hypothesized that a year on Planet Nine would take around 20,000 years, although the planet itself could be a Super Earth.

Origins

It is still unclear how Planet Nine could have gotten into the outer Solar System. Numerous theories declare that it was tidally locked from the Solar System long ago.

Many theories suggest that Planet Nine could have been ejected into the Oort Cloud during the rapid migration of Neptune and the ejection of the Fifth Giant, while others suggest that Planet Nine could be a rogue exoplanet that was captured by the Sun in the past.

Parameters

The planet's mass was stated to be between 5 to 10 Earth masses, implying that it could possibly be between the terrestrial or gaseous state of sorts. However, a later reestimate suggests that Planet Nine's mass is around 6.2 Earth masses. This now means that Planet Nine is more likely to be a either a gaseous or terrestrial Super-Earth.

Another source, however, now cites Planet Nine's mass as 4.4 Earth masses, which puts it in the boundary of it being a terrestrial planet, more over a "Super-Earth".

Its previous orbital data suggested that it had an eccentricity of over 0.2 to 0.5, and an orbital distance between 400 to 800 AU away from the Sun. However, later data now estimates the planet's orbital parameters to be less than this.

Evidence

Recently, scientists observed clustering of objects beyond Neptune's orbit, and that something large was affecting their stability.

This led to the theory of a ninth planet existing in the outermost edges of the Kuiper Belt, but no such planet was found.

Later, scientists theorized that Planet Nine could be a primordial black hole, but this theory is not widely accepted, as there isn't enough evidence to prove the existence of primordial black holes.

Moons

According to Tim^{[Tim Who?]}, Planet Nine might be host to up to 3 moons, each up to 62 miles (100 kilometers) across. If it does have those moons, they might be the key to revealing Planet Nine's presence in the Kuiper Belt, and the secret is tides.

Name

Planet Nine has no official name, and thus wouldn't receive one until its existence has been proven. Via Imaging and such. If is confirmed to exist, the IAU will certify a name, with the priority being given to a name proposed by its Discoverers. It is very likely that Planet Nine would receive a name hailing from Roman or Greek mythology.

Originally, Batygin and Brown referred Planet Nine as "Perturber". Though, this name would slowly be ruled away when they started using the Planet Nine name. A few proposed names were made, such as "Jehoshaphat" or "George", with the latter being a reference to William Herschel's proposed name for the seventh planet in the Solar System, Uranus. Another name, "Phattie", was also proposed, but would never be used too often.

Batygin had also suggested that the planet should be named after David Bowie, and any of the proposed moons of Planet Nine would likely be named after characters from David Bowie's song catalog.

Persephone was also another proposed name for Planet Nine, as it was a popular name used in Sci-fi for planets sitting beyond Neptune. However, it is unlikely that Planet Nine would receive the name "Persephone", as thats already the name of 399 Persephone, a Main-belt Asteroid. Another name, "Telisto", was proposed by Lorenzo Lorio. The said Name comes from the Greek Word, "τήλιστος", or "Farthest" or "Most Remote".

Back in 2018, Alan Stern, a planetary scientist, objected the name "Planet Nine", along with him saying: "It is an effort to erase Clyde Tombaugh's legacy and it's frankly insulting" and suggested the name "Planet X" until the planet is confirmed to exist. He would also then assign a statement with 34 other scientist, mentioning that the use of the Planet Nine name should be discontinued and in favor of culturally and taxonomically neutral terms for such planets. According to Mike Brown: "Planet X isn't a generic reference to some unknown planet, but a specific prediction of Lowell's which led to the (accidental) discovery of Pluto. Our prediction is not related to this prediction."

Gallery