Free Astronomy Magazine March-April 2016

8 Once again, we talk about the existence of a large planet in the remotest depths of our solar system. This time, though, such presence seems all the more con- crete. The thrilling challenge in the field of higher math that 170 years ago led to the discovery of Neptune looks set to be repeated today, although with vastly more powerful means. Planet Nine probable th ever! by Michele Ferrara PLANETOLOGY MARCH-APRIL 2016 I n the May/June 2014 issue, we reported a study by Kevin Luhman (Penn State University) on the possible presence of a planet of significant mass beyond Nep- tune’s orbit. On that occasion, it was point- ed out that no planet as big as Saturn could exist within 10,000 AU from the Sun, and neither another Jupiter within nearly three times that distance. This does not exclude that there could be a smaller size planet, at a considerably lesser distance from the Sun. In the same issue of the mag- azine, we commented the discovery of 2012 VP 113 , a dwarf planet characterized