Mystery orbits in outer solar system not caused by 'Planet Nine': Study

The strange orbits of some objects in the outermost reaches of our solar system are not shaped by the hypothesised 'Planet Nine', but can be explained by the gravitational force of small bodies orbiting the Sun beyond Neptune, scientists say.

The alternative explanation to the so-called 'Planet Nine' hypothesis by researchers at the University of Cambridge in the UK and colleagues proposes a disc made up of small icy bodies with a combined mass as much as ten times that of Earth.

When combined with a simplified model of the solar system, the gravitational forces of the hypothesised disc can account for the unusual orbital architecture exhibited by some objects at the outer reaches of the solar system, according to the study published in the Astronomical Journal.

The new theory is not the first to propose that the gravitational forces of a massive disc made of small objects could avoid the need for a ninth planet.

However, it is the first such theory which is able to explain the ...