The Earth
The Earth is a planet is a solar system. It goes around the sun. The mean distance of the Earth from the Sun is about 149,573,000 km. The planet orbits the Sun at a speed of 29.8 km per second, making one complete revolution in 365.25 days. As it revolves around the sun, the Earth spins on its axis and rotates completely once every 23 hours 56 minutes 4 seconds. The fifth-largest planet of the solar system, the Earth has an equatorial circumference of 40,076km, an equatorial radius of 6,371 km, a polar radius of 6,357 km, and a mean radius of 6,371km. The planet's total surface area is roughly 509,600,000 square km, of which about 29 percent, or 148,000,000 square km, is land. The balanced surface is covered by the oceans and smaller seas. The earth has a single natural satellite, the Moon. The latter orbits the planet at a mean distance of slightly more than 384,400 km.