Astronomers at the University of Louisiana are asserting that there is a gas giant four times the size of Jupiter in the Oort Cloud beyond Pluto. This massive planet, named Tyche, has an orbital radius from the Sun 15,000 times that of planet Earth.
To the Greeks, Tyche was the goddess responsible for the destiny of cities. Her name was provisionally chosen in reference to an earlier hypothesis, now largely abandoned, that the Sun might be part of a binary star system with a dim companion, tentatively called Nemesis, that was thought responsible for mass extinctions on Earth. In myth, Tyche was the good sister of Nemesis.
Tyche will almost certainly be made up mostly of hydrogen and helium and will probably have an atmosphere much like Jupiter’s, with colourful spots and bands and clouds.
The existence of Tyche is primarily based on the gravitational effect it has on comets entering our solar system.