Water | Blue Planet


	Water is the most familiar substance in our lives, and perhaps the most mysterious. It is so plentiful that we call Earth the blue planet—but how did all that water get here? Did it arise from deep within the young Earth or arrive from outer space? Why does our globe have so much, while our neighbors in the solar system have little or none at all? And the mystery doesn't end with water's origins: this substance acts like few others on Earth. It is a shape-shifter, existing as liquid, solid and gas under everyday temperatures and pressures. Yet—trust us—you wouldn't want water to be any less strange or remarkable. If it were, life and Earth as we know it wouldn't exist. Continue through Blue Planet: Three Phases of Water. >>