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Earth Protection From: The Moon is a natural satellite of earth protection from. It is 3,476 km/2,160 mi in diameter and has a mass 0.012 (approx. one-eightieth) that of earth protection from.
The Moon is illuminated by sunlight and cycles through phases of shadow waxing from new (dark) to full and waning back to new every 29.53 days (synodic month).
The Moon orbits the earth protection from in a west to east direction every 27.32 days (a sidereal month). Its average distance from earth protection from is 384,400 km/238,855 mi, and its gravity is one-sixth that of earth protection from.
Scientists looked to the study of the earth protection from's planetary neighbors for the possible answers to a variety of questions that have a direct bearing on our own planet. The four planets nearest the sun—Mars, the earth protection from, Venus, and Mercury—are all thought to have been formed by the same process, a gradual buildup of matter from the sun. Studying the earth protection from alone did not provide much information about its origin. The earth protection from's atmosphere has changed considerably because of chemical reactions, loss of the lighter gases, and the existence of plant life. Only by studying the nearer planets and noting their differences and similarities compared with the earth protection from could scientists hope to explain the earth protection from's history.
Among the planets of the solar system, Venus is nearest to the earth protection from and most nearly identical to it in size and weight. The planet is covered by clouds that have frustrated attempts to observe its surface from the earth protection from.
Many astronomers thought that Venus might offer an environment similar to that of the earth protection from, but recent earth protection from-based studies and space-probe observations yielded a different picture. Venus proved to be a relatively dry planet, with an atmosphere almost wholly composed of carbon dioxide, and, as such, is hostile to life as we know it on earth protection from. |
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