Caltech researchers have found evidence of a giant planet tracing a bizarre, highly elongated orbit in the outer solar system. The object, which the researchers have nicknamed Planet Nine, has a mass about 10 times that of Earth and orbits about 20 times farther from the sun on average than does Neptune (which orbits the sun at an average distance of 2.8 billion miles). In fact, it would take this new planet between 10,000 and 20,000 years to make just one full orbit around the sun.
This is an old article. It references the Batygin and Brown paper from 2016. As of 2024, it is still considered possible, but no direct evidence has been observed, and alternative explanations have been proposed, according to Wikipedia.
Things are looking pretty grim for planet nine, it’s running out of places to hide. It was a cool hypothesis and a gutsy prediction, but I’m afraid that it’s not going to work out.
Won’t the Vera Rubin Telescope (formerly LSST) settle this? It’s going to observe the entire night sky every few nights and provide enough data to find nearby moving objects.
This paper seems to be dated 18 April, 2024. Wouldn’t surprise me if its some sort of re-print, but otherwise would explain why this topic popped up in the media over the last few days. https://arxiv.org/pdf/2404.11594.pdf