(June 25, 2014 at 1:58 am)Wyrd of Gawd Wrote: Some folks think that magic comets brought all of the water to Earth. They can't imagine that the Earth makes its own water as well as oil and various gases.
Actually, while earth made all of its own oil and natural gas (the kind you burn in gas fired stoves in kitchens) it didn't make most of the other gases found in the atmosphere or inside the earth. It didn't make any of the water on its surface, in its oceans, on bond up chemically inside rocks deep within the earth.
All water on earth did come from comets, and there is nothing magical about these comets. The comets which brought water to earth are all, as far as we know, normal run of the mill comets. The main question is when did the comets bearing most of the water currently on the surface of the earth arrive. Did it arrive while the earth was forming, and the water became incorporated into the forming earth and them later erupted onto the surface via volcanos, or did arrive with comets that hit the earth after the formation process was essentially complete.
