The Earth is approximately 8000 miles (13000 km) in diameter, so its circumference is approximately 8000·π = about 25,000 miles (40,000 km). Its surface area is approximately 4·π (4000 mi)<sup>2</sup> = 200 million square miles (510 million km<sup>2</sup>). It has been said that Earth should really be called "water:" most of the Earth's surface, about 70%, is covered by water. In fact, the Pacific and Indian oceans alone cover about half of the Earth. | The Earth is approximately 8000 miles (13000 km) in diameter, so its circumference is approximately 8000·π = about 25,000 miles (40,000 km). Its surface area is approximately 4·π (4000 mi)<sup>2</sup> = 200 million square miles (510 million km<sup>2</sup>). It has been said that Earth should really be called "water:" most of the Earth's surface, about 70%, is covered by water. In fact, the Pacific and Indian oceans alone cover about half of the Earth. |