Origin of Water on Earth

[Dannager]

In a recent thread on the Creationism sub-forum, a participant said the following:

I like to watch shows explaning how the world came about, but not to believe it as true but to... Well, It makes me smile. Some make me laugh out loud. One show tried to explain how the oceans were filled with water. They said it was from a bombardment of comets. The scientist say there is some water in comets.... but the world is covered mostly by water. Can you imagine how many comets would have to fall to earth to not only fill the oceans but also the polar ice caps? Ya cant always believe what you hear or what you appear to see.

NOTE: This thread is created for the purpose of addressing an inaccuracy on the part of a participant in the creationist-only sub-forum. This thread is located on the main Origins Theology board so that debate and discussion may occur.

Now, I'm willing to bet hard money on the show in question not claiming that all water on the planet came from comets because that is plainly absurd. That was probably just a mistake on the poster's part. The water on earth came from a number of different sources, though comets likely were among them. Meteorites also may have been involved to a degree, and outgassing from the earth's crust certainly played a major role in producing the steam necessary to fall back as rainwater to the surface. Earthscape.org has the following to say about the oceans' origins:

Where did all this water come from? The formation of Earth involved the aggregation of planetesimals to form larger bodies which we now call planets. As the Earth formed, approximately 4.6 billion years ago (BYA), nuclear heating and the energy of thousands of collisions with smaller planetesimals and meteorites caused it to become molten, at which time the core of the Earth differentiated into layers based on the density of materials within them. As the Earth's core was differentiating, gases were released. These gases bubbled to the surface where they escaped to outer space (especially the lighter gases like helium and hydrogen) or were held by the forces of gravity to form our atmosphere. This process, called outgassing, was responsible for the release of gases from the interior of the earth that formed our early atmosphere.

In its initial stages, the Earth was too hot for an atmosphere to form. Any gases were superheated and released into space. However, once the Earth cooled sufficiently, sometime in the first 700 million years of its existence, clouds began to form in the atmosphere, and the Earth entered a new phase of development. It began to rain. And it rained and it rained and it rained.

The formation of an atmosphere also protected the Earth from smaller meteorites, which burned up before they impacted the surface. The cloudy atmosphere also reflected some of the radiation from the sun, allowing the Earth to cool further. Eventually, the surface of the Earth solidified and the crustal plates were formed. After several hundred million years, the Earth finally had oceans, and atmosphere, and continents.

For more information on the origins of the ocean in a format that is fairly simple to understand, check out http://www.earthscape.org/t2/chs01/chs01d/chs01da.html.

 

[jereth]

I like to watch shows explaning how the world came about, but not to believe it as true but to... Well, It makes me smile. Some make me laugh out loud.

Funny, that's how I feel when I read Creation magazine!