Solar System and neon, which were always in the gaseous phase in the nebula. Ices, like water, methane, ammonia, hydrogen sulfide, and carbon dioxide, have melting points up to a few hundred kelvins. They can be found as ices, liquids, or gases in various places in the Solar System, whereas in the nebula they were either in the solid or gaseous phase. Icy substances comprise the majority of the satellites of the giant planets, as well as most of Uranus and Neptune (the so-called "ice giants") and the numerous small objects that lie beyond Neptune's orbit. Together, gases and ices are referred
Ice giant the terrestrial and gas giants is relatively straightforward and uncontroversial. The terrestrial planets of the Solar System are widely understood to have formed through collisional accumulation of planetesimals within the protoplanetary disc. The gas giants—Jupiter, Saturn, and their extrasolar counterpart planets—are thought to have formed after solid cores around 10 Earth masses () formed through the same process, while accreting gaseous envelopes from the surrounding solar nebula over the course of a few to several million years (Ma), although alternative models of core formation based on pebble accretion have recently been proposed. Some extrasolar giant planets may instead have formed