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Earth, our beautiful home planet, is the only astronomica object to accomodate life as we know it. Scientists believe Earth was formed approximately 4.5 billion years ago. It is the fifth-largest planet in our solar system. Its equatorial diameter is about the third-closest planet to the sun. The distance from Earth to the sun is roughly 149,600,000 kometres. It takes 365.3 days for Earth to orbit the sun, and 24 hours to rotate on its axis. The surface temperature ranges from -88 to 580 C. Nearly 70 percent of Earth's surface is covered by ocean, which has an average depth of about 4 kilometres. In 2015 it was estimated that 7.3 billion humans are living on Earth. 

Most of Earth's surface is covered by ...