Last year, astronomers announced the existence of an unknown planet in our solar system. However, this hypothesis was subsequently called into question as biases in the observational data were detected. Now, Spanish astronomers have used a novel technique to analyse the orbits of the so-called extreme trans-Neptunian objects and, once again, they report that there is something perturbing them—a planet located at a distance between 300 to 400 times the Earth-sun distance.