The likelihood of a ninth planet exiasting on the edge of our solar system seems increasingly certain, according to NASA.

The space agency says the evidence is hard to ignore and cites strange influences on the Kuiper belt as the clearest reason yet to suspect the large planet is lurking nearby.

If it exists, Planet Nine would be a frigid world roughly 10 times the mass of Earth and around 20 times further away from the sun than Neptune is.

Artist's logarithmic scale conception of the observable universe with the Solar System at the center, inner and outer planets, Kuiper belt, Oort cloud, Alpha Centauri, Perseus Arm, Milky Way galaxy, Andromeda galaxy, nearby galaxies, Cosmic Web, Cosmic microwave radiation and Big Bang's invisible plasma on the edge. (
Image:
Pablo Carlos Budassi)

It's mass appears to be causing observable irregularities in the movement of icy bodies within the belt.

The only thing astronomers have left to do is actually catch a glimpse of the planet.

"There are now five different lines of observational evidence pointing to the existence of Planet Nine," said Konstantin Batygin, a planetary astrophysicist at Caltech in Pasadena, California, whose team may be closing in on the discovery.

"If you were to remove this explanation and imagine Planet Nine does not exist, then you generate more problems than you solve. All of a sudden, you have five different puzzles, and you must come up with five different theories to explain them."

The motions of the extreme trans-Neptunian objects (as illustrated on the right) suggest that there is an unknown planet (left) in the confines of the Solar System. / José Antonio Peñas (SINC) (
Image:
SINC)

The latest sign of Planet Nine's presence involves the solar system's contrarians: objects from the Kuiper Belt that orbit in the opposite direction from everything else in the solar system.

Planet Nine's orbital influence would explain why these bodies from the distant Kuiper Belt end up "polluting" the inner Kuiper Belt.

"No other model can explain the weirdness of these high-inclination orbits," Batygin said. "It turns out that Planet Nine provides a natural avenue for their generation. These things have been twisted out of the solar system plane with help from Planet Nine and then scattered inward by Neptune."

Given the planet's supposed location, it won't be easy to spot.

However, NASA is now convinced that the effects of the planet can't be ignored.