Rosetta Reignites Debate over Earth's Oceans

Source - NASA Science News for Dec. 14, 2014

A popular theory holds that ocean water was brought to Earth by the ancient impacts of comets and asteroids. However, new data from the European Space Agency’s Rosetta spacecraft indicate that terrestrial water did not come from comets like 67P/Churyumov-Gerasimenko.

The complete article can be found here: http://science.nasa.gov/science-news/science-at-nasa/2014/14dec_cometwater/