In the race towards the discovery of Planet Nine, scientists from around the world strive to calculate its orbit using the tracks left by the small bodies that move well beyond Neptune. Now, astronomers from Spain and Cambridge University have confirmed that the orbits of the six extreme trans-Neptunian objects that served as a reference to announce the existence of Planet Nine are not as stable as originally thought.
Through a computer-simulated study, astronomers at Lund University in Sweden show that it is highly likely the so-called Planet 9 is an exoplanet. This would make it the first such body to be discovered inside our own solar system — when or if it is found. The theory is that our Sun, in its youth some 4.5 billion years ago, stole Planet 9 from its original star.