/sci/ - Science & Math

French astronomers might have halved the search area for Planet Nine.

https://news.cnrs.fr/articles/closing-in-on-planet-9
>J. L.: Our method is actually entirely different from that used by the Caltech researchers and it is based on a different set of observational data. As I said, our work relied on a model called INPOP (link is external), which was developed as early as 2003. This model integrates nearly 150,000 observations of planets and asteroids of the Solar System. It enables us to establish ephemerides that can predict, at any given moment, the position of the various bodies of the Solar System, taking into account their mutual gravitational interactions. These ephemerides are so accurate that they can determine the exact distance between Saturn and the Earth at any time, with a margin of error of a mere 75 meters! To test the possibility that a ninth planet of approximately 10 Earth masses might lurk in the Solar System, we entered it into the dynamic INPOP model, using the parameters, and possible configurations suggested by Batygin and Brown. We then recalculated the ephemerides obtained for Saturn in each of these configurations. By comparing these ephemerides to data collected by the Cassini spacecraft (link is external)since 2004 on the actual position of Saturn, we were able to determine that some positions of Planet 9 considerably increased the margin of error of the INPOP model, while others reduced it. Since INPOP has already proved its reliability, we inferred that planet 9 could not be located in zones that would significantly increase the model’s current margin of error. Besides, it is more likely that this planet would be located where its presence reduces this margin.