According to a new study published in the journal Nature on Wednesday, the Earth's ocean may have been created by comets.

The latest analysis of data from NASA's Deep Impact spacecraft shows that comet 103P/Hartley 2 is hyperactive in terms of the material it spews out, compared to the other comets observed up close to date.

On Nov 4, 2010, NASA's EPOXI spacecraft came within 450 miles of Comet Hartley 2, a small comet not even a mile in diameter, which takes about six and a half years to orbit the sun.

New findings from NEOWISE, the asteroid- and comet-hunting portion of NASA's Wide-field Infrared Survey Explorer mission, show that comet Hartley 2 leaves a pebbly trail as it laps the sun, dotted with grains as big as golf balls.

Comet Hartley 2's hyperactive state, as studied by NASA's EPOXI mission, is detailed in a new paper published in this week's issue of the journal Science.