Earth is a small planet of the solar system but the conditions for the existence of life are most favorable on it.
Earth revolves around the sun in an ellipsoidal orbit measuring 2414 million km in length and completes one rotation in 365-1/4 days, but its period of rotation about its axis is 24 hours. Its polar diameter is 12,713 km and equatorial diameter measures l2,756 km. Its atmosphere consists of about 20% oxygen and 80% nitrogen. It has a satellite called Moon at a distance of 357,269 km and revolves around it.
Earth orbits around Sun at about 30 km/s (108,000 km/h), which is enough to cover one Earth diameter (~12,700 km) in 7 minutes, and one distance to the Moon (384,000 km) in 4 hours.
Earth turns around the Sun every 365 ¼ days (1 year). From Earth, this looks like an apparent movement of the Sun with respect to the stars at a rate of ca. 1 degree perday, i.e., a Sun or Moon diameter every 12 hours eastward.
The Earth is sometimes called the Third Rock from the Sun because it is the third closest planet to the sun.
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