The confines of our planetary neighborhood are dark, cold, and mysterious. We do not know what type of structures and bodies live in those regions outside the reach of the light that the Sun gives away. Many questions have been raised about the nature of the so-called Transneptunian bodies, such as the Oort cloud or Planet Nine, a planet that would be part of the solar system and we would not have yet been able to detect observationally. But that could be about to change.

The confines of the Solar System

Beyond Saturn, objects wandering through interplanetary space become invisible to the human eye. So Uranus and Neptune were not discovered until enough optical technologies were available to find them. Something similar happened with Pluto and the other distant bodies called Transneptunians.

Astronomers have predicted the existence of a spherical cloud of opaque, icy rocks and bodies that blankets the solar system at a distance of about one light-year from the Sun. They couldn’t observe any of these bodies due to the immense distance, but they could predict their existence due to their gravitational effects on the rest of the system.

Using the same principles, a team of Caltech researchers has announced that they have “evidence for a giant planet making an unusual and elongated orbit in the outer solar system,” according to a NASA statement.

A new planet?

Experts believe that the so-called Planet Nine could have a mass of around 10 Earths and orbit at an average distance from the Sun equivalent to 20 times the distance of Neptune, the outermost planet from the Sun. Scientists calculated the planet’s orbital period around 15,000 years, according to the authors who published their study in The Astronomical Journal.

Jim Green, Director of NASA’s Division of Planetary Sciences, said discovering a new planet is exciting. “[…] however, [it] is too early to say for sure that a so-called Planet X is out there. We see an early prediction based on models from limited observations. […] If Planet X is out there, we will find it together,” he concludes.

“Although we were initially quite skeptical that this planet could exist, as we continue to investigate its orbit and what it would mean for the outer solar system, we have become increasingly convinced that it is out there. For the first time in more than 150 years, there is strong evidence that the planetary census of the solar system is incomplete,” said Konstantin Batygin, co-author of the paper, in an official Caltech statement.

The mathematical model that led to the Planet X proposal was being used trying to explain why some of the icy bodies and dwarf planets that make up the Kuiper belt clump together as they do. The researchers estimate that the gravitational influence of a body with the characteristics attributed to Planet X could explain the clustering in the Kuiper belt orbits.

The challenge of finding an invisible planet

For astronomers, it is crucial to find an answer to the bodies’ grouping in the Kuiper belt so they can refine our Solar System’s formation model and evolution. So we must aim for the most powerful telescopes since we need incredibly high resolutions to identify such a distant opaque body.