 Two years later in 1955, Odessan astronomer K. N. Savchenko suggested that Ceres, Pallas, Juno, and Vesta were not fragments of Phaeton, but rather its former moons.Phaeton had an additional fifth satellite, assumed to be the size of Ceres, orbiting near the planet's Hill sphere, and thus more subject to gravitational perturbations from Jupiter.As a result, the fifth satellite became tidally detached and orbited the Sun for millions of years afterward, making periodic close misses with Phaeton that slowly increased its velocity.