Gradual "dehydration melting"—leakage of water stored in hydrate minerals of Earth's rocks—could have formed a portion of its water. Water may also have come from volcanism: water vapor in the atmosphere that originated in volcanic eruptions may have condensed to form rain, slowly filling Earth's oceanic basins. read more
But Earth’s early history, including epochs with high ambient temperatures and no enveloping atmosphere, implies that surface water would have evaporated and drifted back into space. The water we encounter today, it seems, must have been delivered long after Earth formed. read more
Researchers from the University of Hawaii believe they have discovered the origin of Earth’s water. For many years, scientists were uncertain whether water was present when our planet formed or if it was carried by comets and asteroids at a later time. read more