Age: 4.6 billion years old. Position: 3rd planet from the sun. Size: 5th largest planet in our solar system Surface Area: 197 million square miles, about 70 percent of the Earth's surface is coveredwith water. Diameter: The Earth has an average diameter of 12,742 kilometers. (7,926 miles) Average Temperature: The temperature at the Earth's core is estimated to be between 5000 and 7000 degrees Celsius. Length of Year: 365.25 days Inclination of Axis: The Earth's axis has a tilt of about 23 ½ degrees. It is this tilt which causes the seasons. Chemical Composition: The Earth is made mostly of iron, oxygen, silicon, magnesium, nickel and sulfur: 34.6% Iron, 29.5% Oxygen, 15.2% Silicon, 12.7% Magnesium, 2.4% Nickel, 1.9% Sulfur, 0.05% Titani...