The Origins of Ice

Ice giants are mostly water probably in the form of a supercritical fluid. The visible clouds likely consist of ice crystals with different compositions. And speaking of methane, as we mentioned last time, the blue color of both Neptune and Uranus appears to come from the presence of methane in their atmospheres. But there's one more thing you may have seen headlines about regarding Uranus and Neptune: Some experts argue that it likely rains diamonds on these planets.