Published: 8:56AM Thursday December 11, 2014 Source: AP <\/p>\n
Rosettas lander Philae safely on the surface of Comet 67P\/Churyumov-Gerasimenko - Source: AP <\/p>\n
The mystery of where Earth's water came from got murkier today when some astronomers essentially eliminated one of the chief suspects: comets. <\/p>\n
Over the past few months, the European Space Agency's Rosetta space probe closely examined the type of comet that some scientists theorized could have brought water to our planet 4 billion years ago. It found water, but the wrong kind. <\/p>\n
It was too heavy. One of the first scientific studies from the Rosetta mission found that the comet's water contains more of a hydrogen isotope called deuterium than water on Earth does. <\/p>\n
\"The question is who brought this water: Was it comets or was it something else?\" asks Kathrin Altwegg of the University of Bern in Switzerland, lead author of a study published in the journal Science. <\/p>\n
Something else, probably asteroids, Altwegg concluded. But others disagree. <\/p>\n
Many scientists have long believed that Earth had water when it first formed, but that it boiled off, so that the water on the planet now had to have come from an outside source. <\/p>\n
The findings from Rosetta's mission to the duck-shaped comet 67P\/Churyumov-Gerasimenko complicate not just the question of the origin of Earth's water but our understanding of comets. <\/p>\n
Until now, scientists pretty much sorted comets into two types: near and far. The near ones, sometimes called the Jupiter family, originally come from the Kuiper Belt outside Neptune and Pluto. The far ones hail from the Oort Cloud, which is much farther out. <\/p>\n
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Rosetta helps eliminate comets as source for Earth's water<\/a><\/p>\n","protected":false},"excerpt":{"rendered":" Published: 8:56AM Thursday December 11, 2014 Source: AP Rosettas lander Philae safely on the surface of Comet 67P\/Churyumov-Gerasimenko - Source: AP The mystery of where Earth's water came from got murkier today when some astronomers essentially eliminated one of the chief suspects: comets. Over the past few months, the European Space Agency's Rosetta space probe closely examined the type of comet that some scientists theorized could have brought water to our planet 4 billion years ago. It found water, but the wrong kind. Continue reading