Liquid Acquisition
Two new scenarios ramp up debate over how Earth got its water
By Ron Cowen
Water is the life of the party on Earth. From shallow creeks to cascading waterfalls and raging rivers, it’s the primal heartbeat of the planet, nurturing a wealth of biological systems from the very simple to the amazingly complex. But no one knows for sure how Earth got this most precious of fluids.
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Some researchers contend that the Earth was born wet. Others assert that the planet only later acquired the liquid, ferried in from distant reaches of the solar system. That long-simmering debate has now reached the boiling point.
Two new ideas for supplying water to the early Earth have come to the forefront in the past few months. In thrashing out which scenario is more likely, researchers hope to develop a guide for finding water-rich and possibly habitable planets beyond the solar system.