An undiscovered, Earth-like planet may be lurking within the solar system, a team of astronomers studying the movement of objects in the Kuiper Belt reports.
Finding planets is not an easy task, except for those that help us by being visible from Earth, such as Jupiter. When searching for exoplanets (planets outside our solar system), we can look for dips in light as they pass in front of their parent stars. We discovered 5,502 planets this way. Considering that we found the first one in 1992, it shouldn’t be a bad pace of discovery.
Discovering objects in our own solar system is a bit more complicated and involves figuring out where to look by observing the movement of other objects. Neptune was discovered after astronomer and mathematician Urbain Le Verrier noticed the difference between the observed orbit of Uranus and the path predicted by the orbit of Newtonian physics. He calculated that the orbit could be explained by the gravitational influence of a planet beyond Uranus. Indeed, German astronomer Johann Gottfried Galle found Neptune when he checked where Le Verrier said the planet should be.
The ninth planet?
In a new paper, astrophysicists Patryk Sofia Lykawka of Kindai University in Japan and Takashi Ito of the National Astronomical Observatory of Japan examined the motion of objects in the Kuiper Belt. Running simulations, the team determined that an Earth-sized planet could explain the unusual movements of objects far beyond Neptune’s orbit.
According to the team, the planet will be about 1.5-3 times the mass of the Earth and will be in an orbit inclined at about 30 degrees. The team suggests where to look next to find evidence of the planet’s existence.
“The results of the KBP [Kepler Belt Planet] scenario support the existence of an as-yet-undiscovered planet in the outermost part of the solar system. Additionally, this scenario also includes data generated by perturbations of the KBP that can be observably tested for the existence of this planet,” the team writes in the conclusion of the study. It also predicts the existence of new TNO [trans-Neptunian object] populations located beyond 150 au (astronomical units) that could serve as signatures. More detailed information on the orbital structure in the distant Kuiper Belt could reveal the existence of any hypothetical planets in the outer solar system or can exclude.”
While this suggestion may sound familiar, the authors write that it is different from the much larger and much more distant “planet 9” that some have theorized.
The research was published on The Astronomical Journal.