ocean

An ocean (from Ancient Greek Ὠκεανός, transc. Okeanós, the sea of classical antiquity) is a body of saline water that composes much of a planet's hydrosphere. On Earth, an ocean is one of the major conventional divisions of the World Ocean, which covers almost 71% of its surface. These are, in descending order by area, the Pacific, Atlantic, Indian, Southern (Antarctic), and Arctic Oceans. The word sea is often used interchangeably with "ocean" in American English but, strictly speaking, a sea is a body of saline water (generally a division of the world ocean) partly or fully enclosed by land.
Saline water covers approximately 72% of the planet's surface (~3.6×108 km2) and is customarily divided into several principal oceans and smaller seas, with the ocean covering approximately 71% of Earth's surface and 90% of the Earth's biosphere. The ocean contains 97% of Earth's water, and oceanographers have stated that less than 5% of the World Ocean has been explored. The total volume is approximately 1.35 billion cubic kilometers (320 million cu mi) with an average depth of nearly 3,700 meters (12,100 ft).
As it is the principal component of Earth's hydrosphere, the world ocean is integral to all known life, forms part of the carbon cycle, and influences climate and weather patterns. It is the habitat of 230,000 known species, although much of the oceans depths remain unexplored, and over two million marine species are estimated to exist. The origin of Earth's oceans remains unknown; oceans are thought to have formed in the Hadean period and may have been the impetus for the emergence of life.
Extraterrestrial oceans may be composed of water or other elements and compounds. The only confirmed large stable bodies of extraterrestrial surface liquids are the lakes of Titan, although there is evidence for the existence of oceans elsewhere in the Solar System. Early in their geologic histories, Mars and Venus are theorized to have had large water oceans. The Mars ocean hypothesis suggests that nearly a third of the surface of Mars was once covered by water, and a runaway greenhouse effect may have boiled away the global ocean of Venus. Compounds such as salts and ammonia dissolved in water lower its freezing point, so that water might exist in large quantities in extraterrestrial environments as brine or convecting ice. Unconfirmed oceans are speculated beneath the surface of many dwarf planets and natural satellites; notably, the ocean of Europa is estimated to have over twice the water volume of Earth. The Solar System's giant planets are also thought to have liquid atmospheric layers of yet to be confirmed compositions. Oceans may also exist on exoplanets and exomoons, including surface oceans of liquid water within a circumstellar habitable zone. Ocean planets are a hypothetical type of planet with a surface completely covered with liquid.

View More On Wikipedia.org
  1. JudgeDredd2010

    Spy in the Ocean

    New Series starts tonight BBC1 7pm 1/4 Deep Thinkers Spy creatures reveal an ocean full of startling ways of thinking, including the largest brain, smart octopi, diving monkeys, creative masterminds and other intriguing intelligence.
  2. photojunky

    Birds, surfers & the Ocean. Beautiful scenery.

    This was shot over two mornings and was made from about only 15-20 minutes of footage. The fog was just right.
  3. icemanonline

    NASA is working on an aerial 'Fluid Cam' that can see through ocean waves

    As title NASA is working on an aerial 'Fluid Cam' that can see through ocean waves Looks interesting..... ice
  4. photojunky

    Next houses that will sadly fall of the cliff into the ocean

    The man made sea wall will only delay the demise.
  5. S

    Answered Ocean Internet Radio keeps dropping out

    I've bought a reconditioned Ocean Digital WR261 internet radio. Although my broadband is at least 30Mbps, I turn off all other devices on the network and the wifi meter on the radio shows a good signal, it has terrible problems connecting to any station at all. I just get Buffering..., maybe a...
Back
Top Bottom