It is at last possible to assert with a reasonable degree of certainty that the enigmatic Planet Nine has been directly observed by astronomers in the outer regions of the Solar System.
Estimates suggest that its mass is between five and ten times greater than that of Earth, and it follows an extremely elongated orbit, completing one revolution around the Sun every 10,000 to 20,000 years. Its distance from the Sun is approximately 20 times greater than that of Neptune.
The hypothesis that there is a ninth planet in the Solar System was first put forward in 2016 by scientists at the California Institute of Technology (Caltech). This proposal was based on the observation of unusual movements of objects in the Kuiper Belt. However, it was only recently, with the assistance of advanced modern telescopes, that direct observation of the planet was made possible.
The object meets all official criteria for a true planet and is likely to be similar in composition to Uranus or Neptune. This is the first significant addition to the Solar System since the discovery of Neptune in 1846.
