planetary orbits around stars in binary systems are always unstable
Circumbinary planet Further work on the system[8] showed that the orbits proposed for the candidate planets were catastrophically unstable on timescales far shorter than the age of the system. Indeed, the authors found that the system was so unstable that it simply cannot exist, with mean lifetimes of less than a thousand years across the whole range of plausible orbital solutions. Like other planetary systems proposed around similar evolved binary star systems, it seems likely that some mechanism other than claimed planets is responsible for the observed behaviour of the binary stars - and that the claimed planets simply do not exist.
Moons of Jupiter The physical and orbital characteristics of the moons vary widely. The four Galileans are all over 3,100 kilometres (1,900 mi) in diameter; the largest Galilean, Ganymede, is the ninth largest object in the Solar System, after the Sun and seven of the planets, Ganymede being larger than Mercury. All other Jovian moons are less than 250 kilometres (160 mi) in diameter, with most barely exceeding 5 kilometres (3.1 mi). Their orbital shapes range from nearly perfectly circular to highly eccentric and inclined, and many revolve in the direction opposite to Jupiter's spin (retrograde motion). Orbital periods range from seven hours (taking less time than Jupiter does to spin around its axis), to some three thousand times more (almost three Earth years).