Venus (astronomy)

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Second planet from the Sun. It can approach Earth to within 38 million km/24 million mi, closer than any other planet. Its mass is 0.82 that of Earth. Venus rotates on its axis more slowly than any other planet, from east to west, the opposite direction to the other planets (except Uranus and the dwarf planet Pluto).

Mean distance from the Sun
108.2 million km/67.2 million mi

Equatorial diameter
12,100 km/7,500 mi

Rotation period
243 Earth days

Year
225 Earth days

Atmosphere
Venus is shrouded by clouds of sulphuric acid droplets that sweep across the planet from east to west every four days. The atmosphere is almost entirely carbon dioxide, with an atmospheric pressure of 90 times that at the surface of the Earth. The gas traps the Sun's heat by the greenhouse effect and raises the planet's surface temperature to 480°C/900°F

Surface
consists mainly of silicate rock and may have an interior structure similar to that of Earth: an iron-nickel core, a mantle composed of more mafic rocks (rocks made of one or more ferromagnesian, dark-coloured minerals), and a thin siliceous outer crust. The surface is dotted with deep impact craters. Some of Venus's volcanoes may still be active

Satellites
no moons

The first artificial object to hit another planet was the Soviet probe Venera 3, which crashed on Venus on 1 March 1966. Later Venera probes parachuted down through the atmosphere and landed successfully on its surface, analysing surface material and sending back information and pictures. In December 1978, NASA's Pioneer Venus probe went into orbit around the planet and mapped most of its surface by radar, which penetrates clouds. During four years from August 1990 the US space probe Magellan mapped 99% of the planet's surface to a resolution of 100 m/330 ft. The European Space Agency plans a mapping mission called the Venus Express, to begin in 2006 and last about 17 months.

The largest highland area is Aphrodite Terra near the equator, half the size of Africa. The highest mountains are on the northern highland region of Ishtar Terra, where the massif of Maxwell Montes rises to 10,600 m/35,000 ft above the average surface level. The highland areas on Venus were formed by volcanoes.

Venus has an ion-packed tail 45 million km/28 million mi in length that stretches away from the Sun and is caused by the bombardment of the ions in Venus's upper atmosphere by the solar wind. It was first discovered in the late 1970s but it was not until 1997 that the Solar Heliospheric Observatory revealed its immense length.

Red symbolizes the revolution of 1984. The five-pointed star is said to signify the revolution or freedom. Green stands for the country's natural resources. Effective date: 4 August 1984. >>