Extraterrestrial liquid water to have water, including liquid pressurised by non-atmospheric means, dissolved into mineral through ionising radiation. Water has also been found to flow on the large asteroid 4 Vesta heated through periodic impacts. Most known extrasolar planetary systems appear to have very different compositions to the Solar System, though there is probably sample bias arising from the detection methods. The goal of current searches is to find Earth-sized planets in the habitable zone of their planetary systems (also sometimes called the "Goldilocks zone"). Planets with oceans could include Earth-sized moons of giant planets, though it remains speculative whether such 'moons' really
Phase (matter) and gas become indistinguishable. Above the critical point, there are no longer separate liquid and gas phases: there is only a generic fluid phase referred to as a supercritical fluid. In water, the critical point occurs at around 647 K (374 °C or 705 °F) and 22.064 MPa. An unusual feature of the water phase diagram is that the solid–liquid phase line (illustrated by the dotted green line) has a negative slope. For most substances, the slope is positive as exemplified by the dark green line. This unusual feature of water is related to ice having a lower density than