Our Oceans, Lakes And Rivers Don’t Come From Icy Meteorites, Say Scientists
This week we discovered that all the water on Earth is older than the Sun, but we still don’t know where it came from.
Not from “melted” meteorites, suggests a new study published today in Nature, which analyzed meteorites that until recently were in space since the solar system’s formation 4.5 billion years ago. “Melted” in this context means that a meteorite comes from an asteroid that are igneous—which have been melted into magma. Such meteorites regularly fall to Earth.
Despite there being a common belief among astronomers that the origin of water on Earth’s meteorites (and possibly comets) the scientists discovered that these melted meteorites are among the driest extraterrestrial materials ever measured.
“We wanted to understand how our planet managed to get water because it’s not completely obvious,” said Megan Newcombe, Assistant Professor of Geology at University of Maryland. “Getting water and having surface oceans on a planet that is small and relatively near the Sun is a challenge.”
The scientists analyzed volatile elements—including magnesium, iron, calcium and silicon—inside seven achondrite or “stony” meteorites that have their origin within planetesimals in the early solar system.
Some of their meteorite samples came from the warm and dry inner solar system while other rarer samples came from its colder, icier outer reaches. However, the results revealed that water comprised less than two millionths of their mass. So not all outer solar system objects are rich in water, as was thought.
“We knew that plenty of outer solar system objects were differentiated, but it was sort of implicitly assumed that because they were from the outer solar system, they must also contain a lot of water,” said Sune Nielsen, a study co-author and geologist at the Woods Hole Oceanographic Institution. “Our paper shows this is definitely not the case. As soon as meteorites melt, there is no remaining water.”
Around 71% of Earth’s surface is covered in water, but how it got here remains a mystery.
Wishing you clear skies and wide eyes.