to be sutible for living??
2007-02-23 20:25:46 · 3 answers · asked by alaa h 1 in Science & Mathematics ➔ Earth Sciences & Geology
The earth is not 75% water. About 71% of the surface is covered in water - but the planet is composed mostly of iron (35.0%), oxygen (28.0%), silicon (17.0%), magnesium (15.7%), nickel (1.5%), calcium (1.4%) and aluminium (1.4%).
The mass of the oceans is approximately 1.35 × 10^18 tonnes, or about 1/4400 of the total mass of the Earth.
As for why there is so much water on the surface... well most likely there was a lot of water in the early solar system, and it was captured by the earth's gravity -- since the planet was molten the water migrated to the surface because it is much less dense than rock/metal. The heaviest elements (iron, nickle, etc) sunk to the center of the planet, while the ones in between (silicon, calcium, etc) migrated to the middle/upper portion that is refered to as the mantle.
Some scientists believe that much of the water came from planetary bombardment by comets soon after the formation of the planet - personally I find this theory to be highly speculative and probably not true.
2007-02-23 22:42:00 · answer #1 · answered by brooks b 4 · 0⤊ 0⤋
It isn't, 71% (not 75%) of the surface of the Earth is covered with water. The depth of that water deosn't even make it half of the Earth's crust. When looking at the entire volume of the Earth, well over 99% is the core and mantle while well under 1% is the crust, along with the water.
2007-02-24 23:16:45 · answer #2 · answered by Amphibolite 7 · 0⤊ 0⤋
No, its because the Earth is made up of mainly Hydrogen and Oxygen, the two elements needed to make water.
2007-02-24 04:29:32 · answer #3 · answered by slaughter114 4 · 0⤊ 1⤋