Mystery of Planet 9 deepens: 'Rogue' world may have been EXILED to the edges of our solar system by the sun billions of years ago

  • The idea of a ninth planet lurking beyond Neptune was published last January
  • Since then a series of studies have suggested different things about the planet
  • These include the idea it was captured from floating in space by our sun's gravity
  • But a new study suggests that it is unlikely that it was captured, and instead it probably formed inside our solar system

By ABIGAIL BEALL FOR MAILONLINE

Published: | Updated:

Whether or not there is a ninth planet lurking in our solar system far beyond Neptune is still a mystery.

Since it was hypothesised last year, many theories have come out regarding how the planet could have got there – some suggesting it may have been floating out in space on its own and been 'captured' by our sun.

Now, a new study suggests the mysterious planet, if it exists, was not captured by our sun but instead it formed close to the other planets and was banished further out by the sun.

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A new study suggests that Planet 9, if it exists, was not captured by our sun but instead it formed close to the other planets and was banished further out by the sun (artist's impression pictured)

A new study suggests that Planet 9, if it exists, was not captured by our sun but instead it formed close to the other planets and was banished further out by the sun (artist's impression pictured)

WHAT IS PLANET 9?

Astronomers believe that the orbits of a number of bodies in the distant reaches of the solar system have been disrupted by the pull of an as yet unidentified planet.

First proposed by a group at CalTech in the US, this alien world was theorised to explain the distorted paths seen in distant icy bodies.

In order to fit in with the data they have, this alien world - popularly called Planet Nine - would need to be roughly four time the size of Earth and ten times the mass.

Researchers say a body of this size and mass would explain the clustered paths of a number of icy minor planets beyond Neptune.

Its huge orbit would mean it takes between 10,000 and 20,000 years to make a single pass around the sun.

The theoretical Planet Nine is based on the gravitational pull it exerts on these bodies, with astronomers confident it will be found in the coming years.

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Researchers at the University of Sheffield in the UK and ETH Zurich ran simulations of a variety of scenarios, including those that a free floating planet (FFLOP) was captured by our own star.

They found that the chances of a planet like this being captured are only one in six, at best, meaning this scenario is unlikely.

'Depending on the initial conditions of the star-forming regions, only 5 - 10 of 10,000 planets are captured onto orbits that lie within the constraints for Planet 9,' the authors, led by Richard Parker, wrote. 

'Even if the sun formed in a very hostile, very dynamic, very violent environment, in one of these densely populated clusters, it's still unlikely that it captured Planet Nine,' Mr Parker told New Scientist.

Since its existence was first suggested, Planet Nine has caused a lot of debate in the community.

In June this year, researchers released controversial findings that suggest the mysterious Planet 9 may not exist after all. 

The researchers found that the chances of a planet like this being captured are only one in six, at best, meaning this scenario is unlikely (artist's impression pictured)

The researchers found that the chances of a planet like this being captured are only one in six, at best, meaning this scenario is unlikely (artist's impression pictured)

Analysis of a four-year survey found that observation bias may have been to blame for data that built the argument in its favour.

But a month later, another study revived hopes for the ninth planet lurking within our solar system.

Recent studies have also suggested the possibility of another planet roughly the size of Mars thought to exist in the solar system, dubbed 'Planet 10,' but the researchers say it's unrelated to the planet supported by their data.

Since the planet was first proposed, several studies have attempted to find evidence of its existence far beyond Neptune based on several signatures it would leave

Since the planet was first proposed, several studies have attempted to find evidence of its existence far beyond Neptune based on several signatures it would leave

'Given the current definition of planet, this other mysterious object may not be a true planet, even if it has a size similar to that of the Earth, as it could be surrounded by huge asteroids or dwarf planets,' the astronomer explains.

'In any case, we are convinced that Volk and Malhortra's work has found solid evidence of the presence of a massive body beyond the so-called Kuiper Cliff, the furthest point of the trans-Neptunian belt, at some 50 AU from the sun, and we hope to be able to present soon a new work which also supports its existence.'

The study has been published in the journal in Monthly Notices of the Royal Astronomical Society. 

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