Beyond Neptune

Simulation provides further evidence for “Planet 9”

Künstlerische Illustration: So könnte „Planet 9“ aussehen.

(Bild: Caltech/R. Hurt (IPAC))

Since Pluto was demoted to a dwarf planet in 2006, Neptune has been considered the outermost planet in our solar system. However, due to unusual orbits of celestial bodies in the Kuiper Belt, astronomers assume that there is another, previously unknown planet, "Planet 9". A computer simulation now provides evidence for this theory.

No one has yet seen "Planet 9", which orbits far beyond Neptune. However, a small team of planetary researchers from the California Institute of Technology, the Université Côte d'Azur and the Southwest Research Institute has now reported possible new evidence of "Planet 9".

As the team led by Konstantin Batygin and Michael E. Brown from the California Institute of Technology report in advance via ArXiv.org and in the specialist journal "The Astrophysical Journal Letters", they have run through the orbital movements of numerous trans-Neptunian objects in various computer simulations.

Viele der transneptunischen Objekte haben Umlaufbahnen, die sich am besten durch einen neunten Planeten erklären lassen.

(Bild: NASA)

Position could not be determined
Based on computer simulations, the researchers came to the conclusion that the most plausible explanation for the behavior of the objects is interference with the gravity of a large, distant planet (i.e. "Planet 9"). Unfortunately, the simulations were not of the kind that would allow the researchers to determine the planet's position in the solar system.

Batygin and Brown had already reported evidence of the existence of a ninth planet in our solar system in 2016. The celestial body was around ten times heavier than the Earth, they said at the time. "Planet 9" orbits the sun at an average distance of 20 times that of Neptune, currently the outermost known planet in our solar system.

Since the demotion of Pluto to a dwarf planet, Neptune has been considered the outermost planet in our solar system.

(Bild: AFP/ESO/P. Weibacher)

Smaller version of Uranus and Neptune?
This means that the planet is so far away from its central star that it would probably take 10,000 to 20,000 years to orbit the sun, the duo reported in the magazine "Nature". The researchers believe that the mysterious celestial body is a small ice giant with an envelope of hydrogen and helium - a smaller version of Uranus and Neptune, so to speak.

The researchers now hope that their theory can soon be put to the test: With the help of the Vera C. Rubin Observatory, a reflector telescope with a large field of view, which is currently being built in Chile and is due to be completed in 2025. When it scans the firmament for the first time next year, it could enable the first discovery of a new planet in almost 180 years.