Everything that we will study about the oceans, from the currents and weather patterns to the migration of gray whales, is ultimately tied in to "Plate Tectonics." Basically, this is because the configuration of the oceans is the visible end-product of the dynamic plate tectonic functions. In order to fully understand this, we must understand what a "plate" is. The starting point is the origin of the Earth itself.

Major steps in the origin of the Earth:

1. Big Bang. 15 billion years ago. Prior to the Big Bang, all of the mass and energy of the universe in one point. Universe very hot at first and is cooling. Gases and debris coalesced into galaxies; within galaxies are stars.

2. Formation of the solar system. Stars and planets condensced from a solar nebula. 5 billion years ago, spinning of the nebula caused gravitational accretion of a protosun (mostly hydrogen and helium) and spinning rate increased. Left over junk accreted into rings which became planets. Lasted 50 to 70 million years

3. Segregation of the early Earth. Originally, Earth was a spinning ball of mixed material. Bombardment by meteors, gravitational collapse, and heat from decaying elements caused Earth to melt. As the planet melted, heavy elements such as iron, fell toward the center and lighter elements, such as silicon and aluminum, went toward the surface. This layering is called "density stratification.

4. Cooling of the Earth. Earth had a hard outer surface by about 4.6 billion years ago. Early atmosphere and later, oceans, formed from outgassing of Earth's interior. Planet was too hot at first. Early atmosphere had no free oxygen.

Composition of the Earth's Layers:

By material:

Crust at top, less than 1% of Earth's volume, density of about 2.9 g/cm3. Lies at top because of isostatic equilibrium.

Mantle in middle, mostly oxygen, magnesium, and silicon, density about 4.5 g/cm3. Makes up 83% of the Earth's volume. The boundary of the crust and mantle is the Mohorovicic Discontinuity, or MOHO.

Core at center, mostly iron and nickel, very dense at 13 g/cm3. 16% of Earth's volume. The boundary between the mantle and the core is the Gutenberg Discontinuity.

By physical properties:

Lithosphere at top. Cool, rigid outer layer composed of crust and top of mantle.

Asthenosphere. Below lithosphere, made up of hot, flowing material.

Lower mantle. Same chemical composition as the asthenosphere, but the lower mantle is rigid.

Outer core. Behaves as a thick liquid.

Inner core. Behaves as a solid.

5. Life developed. From alien spaceships colonizing the planet, NOT! Best guess, caused by enegy input (e.g., lightning strikes or meteor hits) into water containing building blocks of life: water, ammonia, methane, hydrogen. Formation known as "biosynthesis."

6. Construction of the oceans and continents. Caused by segregation of materials based by composition. The various changing shapes are due to plate tectonics. At first, continental plates were smaller and lacked granite, and plate motions were much faster.

Based on this history, probably an easy bet that oceans exist, or existed, elsewhere. As for life...

Facts:

Oceans cover 71% of the Earth's surface and the oceans contain 97% of the Earth's available water.

Average depth of the ocean is about 3,800 meters.

Deepest spot in the present oceans is the Mariana Trench at 11,022 meters.

Hawaii is the tallest mountain (taller than Mt. Everest) at 10,203 meters.

Big Bang about 15 billion years ago.

Earth formed into layers by 4.6 billion years ago.

Oldest Earth rocks found are 4.0 billion years ago.

Oldest fossils found (by Stanley Awramik) are 3.5 billion years old. Some form of bacteria. Recent Martian fossils are dubious (my bias).

Free oxygen in atmosphere at about 2.5 billion years ago.

http://www.damtp.cam.ac.uk/user/hawking/BOT.html

Steven Hawking's explanation for the Big Bang…need I say more?

http://imagine.gsfc.nasa.gov/docs/ask_astro/answers/970922g.html

Detailed answer to the question, "how do we know about the Big Bang?" citing astrophysical techniques.

http://www.earth.nasa.gov/gallery/index.html

Very cool site of NASA space images

Look for more to come…..