First comet found with ocean-like water

Oct. First comet found with ocean-like water - ANN ARBOR, Mich.—New evidence supports the theory that comets delivered a significant portion of Earth's oceans, which scientists believe formed about 8 million years after the planet itself. The findings, which involve a University of Michigan astronomer, are published Oct. 5 online in Nature. "Life would not exist on Earth without liquid water, and so the questions of how and when the oceans got here is a fundamental one," said U-M astronomy professor Ted Bergin, "It's a big puzzle and these new findings are an important piece." Bergin is a co-investigator on HiFi, the Heterodyne Instrument for the Infrared on the Hershel Space Observatory. With measurements from HiFi, the researchers found that the ice on a comet called Hartley 2 has the same chemical composition as our oceans. Both have similar D/H ratios.