How Did Earth's First Oceans Form?

Question

(Scientifically!)

It's For my science homework!

Answer 1

That is a question that no one has ever proven the answer to.  However, there are two main theories: that water came from inside the earth as volatiles separated out and migrated to the surface; and that water was introduced from extraplanetary bodies that crashed onto the earth in its youth.

I favor the former theory myself.  The impact theory is invoked because the early earth did not have a magnetic field protecting it from solar wind and the volatiles were presumably blown away as fast as they came out.

Answer 2

Current theory is that as the Earth cooled and coalesced, the various elements within it seperated. Denser iron went towards the middle of the planet, and less dense material such as water came towards the surface. Thus, early volcanism created the first oceans.

The asteroid theory is a bit similar, except that early in our planet's history everything was an asteroid. Think of giant gobs of stuff including iron-rich asteroids and water-rich asteroids floating around, eventually collapsing into a massive ball of stuff. As it coalesces, the denser stuff moves towards the middle and the lighter stuff moves towards the outside. That is kind of what happened 5 billion years ago.

That was a long time ago, however, and nobody was around back then. Our best guesses are inferred from other objects in the solar system. Saturn's moon Europa is rather interesting, because the entire surface is water (ice), and it is not known how deep that water goes, exactly where it came from, and why there is so much of it on some moons and not on others. In reality, then, nobody really knows the answer to your question.

Answer 3

Water was brought to the Earth by means of asteroids. Millions of years ago, as the Earth was evolving, asteroids crashed into the Earth carrying frozen water with them. As you can imagine, this would have taken millions of Asteroids to achieve this. It would have also taken millions of years.

Answer 4

The water was already there prior to dry land.  On the third day of creation, God said "let the waters under the heaven be gathered together unot one place, and let the dry land appear: and it was so.  and God called the dray land Earth, and the gathering together of the waters called he Seas...."