Planet Blue
Planet Blue, also known as Earth, is our home planet. It is called Planet Blue because the ocean occupies 71% (3 quarters) of our planet's surface. But where did all that water come from? The ocean has been here for 4 billion years. But 4 and a half billion years ago, Earth was just a lava ball. There was no place for liquid water. Although, deep in Earth, the ingredients were already there. As the volcanoes exploded, one of the gases it let out was steam. Scientists think it rained for thousands of years. But even this relentless down pour only delivered half of the water we have today. Scientist believe that the rest came from outer space. Throughout thousands of years Earth was hit by thousands of comets containing more than 250 000 tons of water that crashed down on earth. When the bombardment was done, it delivered half the water in our oceans. Water is what makes Earth different from every other planet in our solar system.
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