image: The dashed white line in this illustration shows the boundary between the inner solar system and outer solar system, with the asteroid belt positioned roughly in between Mars and Jupiter. A bubble near the top of the image shows water molecules attached to a rocky fragment, demonstrating the kind of object that could have carried water to Earth.
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Credit: Jack Cook/Woods Hole Oceanographic Institution
Water makes up 71% of Earth’s surface, but no one knows how or when such massive quantities of water arrived on Earth.
A new study published in the journal Nature brings scientists one step closer to answering that question. Led by University of Maryland Assistant Professor of Geology Megan Newcombe, researchers analyzed melted meteorites that had been floating around in space since the solar system’s formation 4 1/2 billion years ago. They found that these meteorites had extremely low water content—in fact, they