Were Comets the source of the Earth's oceans?

Recently, scientists have been asking an interesting question: Where has all the Earth's water come from? It's not such a simple question, and the answer is a little more intriguing than one might suppose.

LOS ANGELES, CA (Catholic Online) - Certainly, God created the heavens and the earth. Aside from the (widely considered allegorical) story of creation in Genesis, the precise details have proved somewhat elusive. Scientists have a fairly good idea how the earth was actually formed, but many tantalizing questions continue to pique curiosity.

The heart of the problem has to do with changes in Earth's temperature since its formation. For millions of years after the formation of the planet, the temperature was too high for water to exist on the surface. That means, water could not have formed or collected on the surface at the same time the planet formed since the planet for its first several million years, was essentially molten rock all the way to the core. This basic understanding has led scientists to search for the origin of water on the blue planet. 

Many people have a notion that water is a scarce resource in the universe, but they would be wrong. Hydrogen is the most abundant element in the universe. Oxygen, the other elementary component of water, is also very abundant throughout the universe. Often, these two elements combine and form water in space. Comets, for example are made up almost entirely of water, or more precisely ice. Great clouds of water have also been observed in deep space--clouds so vast they could fill our planet's oceans trillions of times over.

But the question remains, how did that water get to Earth, and fill our oceans, which contain virtually 99 percent of all our water?

To obtain the answer, scientists have been looking at other solar systems. In recent years, scientists have learned that planets are common around stars -- most stars seem to have planetary systems. On the fringes of these planetary systems, there are clouds and research indicates that these clouds are filled with ice and water vapor. 

A similar cloud, known as the Oort cloud, is believed to surround our solar system. The Oort cloud is filled with comets which occasionally swing past the Sun and become visible to observers on Earth. In fact, dozens of comets swing past the sun by every year, but the great majority of them are too small and faint to be seen by non-professional observers on Earth. 

It also believed, that billions of years ago the Oort cloud was far more dense than it is today. At that time, it's believed that millions of comets routinely streaked through the inner solar system and occasionally struck the Earth. In doing so, they delivered their H2O to the surface where it condensed and formed oceans.

Observation of other solar systems outside of our own, shows that enough water exists in these clouds to fill the oceans of a great many planets.

As a final proof, scientists have also recently learned that the comets which routinely sail through our inner solar system happen to have precisely the same chemical composition in their water as the Earth's oceans, suggesting they both share a strong common link.

While scientists may have conclusively discerned how water reached the surface of the planet, they must surely stand evermore in awe at the forces of creation.

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