Formation and evolution of the Solar System gravitational push against the outer planets, possibly causing Neptune to surge past Uranus and plough into the ancient Kuiper belt. The planets scattered the majority of the small icy bodies inwards, while themselves moving outwards. These planetesimals then scattered off the next planet they encountered in a similar manner, moving the planets' orbits outwards while they moved inwards. This process continued until the planetesimals interacted with Jupiter, whose immense gravity sent them into highly elliptical orbits or even ejected them outright from the Solar System. This caused Jupiter to move slightly inward. Those objects scattered by Jupiter into highly elliptical
Mongo (fictional planet) peoples of Mongo have evolved into different forms, such as the winged Hawkmen, the tailed Lion Men, and the underwater dwelling Coralians. Mongo is about half the diameter of Earth but is considerably denser, so its gravity is only slightly weaker than the Earth's, though it still allows Flash Gordon to put his gymnastics skills to good use. Mongo has a variety of climates, and is inhabited by enormous, dinosaur-like monsters. In Alex Raymond's comic strip and the Flash Gordon movie serials, Mongo was shown as a rogue planet that had drifted into Earth's solar system. Later versions of the