what is the diameter of the earth in km
Earth The shape of Earth is approximately oblate spheroidal. Due to rotation, the Earth is flattened along the geographic axis and bulging around the equator.[92] The diameter of the Earth at the equator is 43 kilometres (27 mi) larger than the pole-to-pole diameter.[93] Thus the point on the surface farthest from Earth's center of mass is the summit of the equatorial Chimborazo volcano in Ecuador.[94][95][96][97] The average diameter of the reference spheroid is 12,742 kilometres (7,918 mi). Local topography deviates from this idealized spheroid, although on a global scale these deviations are small compared to Earth's radius: The maximum deviation of only 0.17% is at the Mariana Trench (10,911 metres (35,797 ft) below local sea level), whereas Mount Everest (8,848 metres (29,029 ft) above local sea level) represents a deviation of 0.14%.[n 13]
Ocean The total mass of the hydrosphere is about 1.4 quintillion metric tons (7018140000000000000♠1.4×1018 long tons or 7018150000000000000♠1.5×1018 short tons), which is about 0.023% of Earth's total mass. Less than 3% is freshwater; the rest is saltwater, almost all of which is in the ocean. The area of the World Ocean is about 361.9 million square kilometers (139.7 million square miles),[9] which covers about 70.9% of Earth's surface, and its volume is approximately 1.335 billion cubic kilometers (320.3 million cubic miles).[9] This can be thought of as a cube of water with an edge length of 1,101 kilometers (684 mi). Its average depth is about 3,688 meters (12,100 ft),[9] and its maximum depth is 10,994 meters (6.831 mi) at the Mariana Trench.[29] Nearly half of the world's marine waters are over 3,000 meters (9,800 ft) deep.[16] The vast expanses of deep ocean (anything below 200 meters or 660 feet) cover about 66% of Earth's surface.[30] This does not include seas not connected to the World Ocean, such as the Caspian Sea.