Earth, our beautiful home planet, is the only astronomical object to accommodate 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 12,074 kilometers. Earth is the third-closest planet to the sun. The distance from Earth to the sun is roughly 149,600,000 kilometers. 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 58°C. Nearly 70 percent of Earth's surface is covered by ocean, which has an average depth of about 4 kilometers. In 2015 it was estimated that 7.3 billion humans are living on Earth. 1/ How many years ago did scientists believe Earth was ? ………………………………………………………………………………………………… 2/ Is Nearly 70 percent of Earth's surface covered by ocean? …………………………………………………………………………………………………