Naked Science examines different theories on the origins of Earth's water, fueling the debate over water on other planets and the likelihood of alien life.
When the Earth was being formed, it was too hot to include water in the mix. Scientists came to believe that the liquid covering most of our planet's surface was brought here via comets. Recent research reveals that the moisture held by comets varies somewhat from the liquid that now fills our oceans, so where else could the water have come from? New theories incorporating different sources have been proposed.
