Oceans may be a standard accessory on newly formed planets.

The building blocks of rocky planets carry small amounts of water. That water may be what forms the oceans on the young planets according to a report by Lindy Elkins-Tanton of the Massachusetts Institute of Technology in the journal Astrophysics and Space Science.

Many researchers believe that oceans formed on new planets after they had cooled and were bombarded by comets and other icy objects. But Elkins-Tanton noted that the building blocks of planets, called planetisimals, contain at least .001 to .01 percent water. Samples of meteorites that originated from planetisimals suggest this is so.

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The small amount of water found in planetisimals may not seem like enough to form oceans, unless one considers that the mass of the oceans is only .02 percent of the Earth's mass, not including the core.

Elkins-Tanton analyzed every step of the planet formation process to determine where the water would go. She believes that after planetary formation the water evaporates and forms a dense steam atmosphere. The steam then condenses to form oceans.

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Many planets may start out with oceans, but the subsequent fate of the oceans depends on other planetary conditions, such as distance from the sun.

Further studies may explain why Earth kept it's liquid oceans, but Venus and Mars did not.

PHOTO: The Pacific, one of Earth's fine oceans; Wikimedia Commons

IMAGE: Artist's conception of early Earth; NASA