Fourth form of water confirmed! What is the rare 'plastic ice' recently discovered by scientists?

Water behaves in strange ways under extreme conditions. Scientists have now confirmed a fourth form of ice, called Plastic Ice VII. This rare phase allows water molecules to rotate freely while staying in a solid structure. The discovery, led by Livia Bove from Sorbonne University, helps scientists understand how water behaves in extreme planetary environments.

What Makes Plastic Ice VII Unique?
Unlike regular ice, Plastic Ice VII has a rigid structure but allows molecular rotation. Scientists first predicted its existence in 2008. Now, using advanced neutron-scattering experiments, they have confirmed it. The ice forms under pressures above three gigapascals (GPa), about 30,000 times Earth's atmospheric pressure. It also needs temperatures above 450 Kelvin (177°C).

How Did Scientists Find It?
Researchers used neutron scattering and diamond-anvil cells to study tiny ice samples. These tools allowed them to observe molecular movement at an atomic scale. Their findings revealed that while the ice stays solid, its molecules rotate in specific directions.

This discovery changes our understanding of water in space. Ice VII, another extreme phase, exists on Jupiter’s and Saturn’s icy moons, such as Ganymede and Titan. The existence of Plastic Ice VII suggests that water behaves even more unpredictably in space.