Question

Does the water only exist on the earth?

Answer 1

Water is indeed quite commonplace throughout the universe. Water appears in nature in all three common states of matter (solid, liquid, and gas). In space, it is abundant in the solid and gaseous forms, though the liquid form has been discovered only on Earth so far. This is due to the fact that in space, water can only exist as a gas or ice since the vacuum of space prevents the liquid state of water. Therefore, there exists lots of water in the form of ice below the Martian surface, on the moons of the outer planets, and on the dwarf planets beyond Neptune. The tails of comets also frequently consist of water ice and dust sublimating from the comet body and blowing away in the solar wind.

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