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In several ways, Venus is the Earth's twin planet. It is the closest to our planet in mass(.815 Earth masses),radius(6,052km),and surface gravity(.91 times the Earth's).
Like Mercury, Venus has been known since ancient times. In fact, when it is far enough from the sun, it is the third brightest object in the sky to the sun and moon. Venus,
named for the Greek goddess of love, and until the 1950s was thought to be a tropical paradise covered by thick clouds. This
turned out not to be the case. The Venera, Mariner, and Magellan missions revealed that the planet is even hotter than indicated by its nearness to the sun. The surface temperature
of Venus is about 464 degrees Celsius. This makes it the hottest planet in the solar system. The reason for the extreme temperatures is the abundance(96%) of carbon dioxide contained in
the atmosphere. The pressure at the surface of Venus is 91 atmospheres, which means it is 91 times the pressure on the surface of the Earth.
Venus orbits the sun once every 224.7 Earth days, and has an extremely long day. It rotates once every 243 days, which means that a Venus day is longer than a Venus year. Unlike most planets in the solar system, Venus rotates west to east. This is called a retrograde rotation. Although it is similar to the Earth in many ways, scientists have yet to detect a magnetic field surrounding Venus. This implies that it does not have a liquid iron core, or perhaps it does not rotate fast enough to generate a magnetic field. There have been several missions to the planet Venus. The U.S. probe Mariner 2 completed the first successful mission to Venus in 1962, and was soon followed by the Soviet Union's Venera 4,5, and 6. The Venera spacecrafts entered the atmosphere of Venus and were probably melted or demolished soon after by the extreme conditions of the atmosphere. Venera 7 was able to make it to the surface of Venus and was followed by Veneras 8-16 and other Soviet Union probes named Vega 1 and 2. The U.S. sent Pioneer Venus 1 and 2 in 1978 and later Magellan which mapped about 98% of the surface of Venus in 1990. |
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