Venus

• Venus is only slightly smaller than Earth, and comes nearer to us than any other planet. At its closest it is about 26 million miles (42 million km) away. More space probes have been sent to Venus than to any other planet because it is so close.



• Venus is shrouded by a dense blanket of poisonous gases. Clouds of sulphuric acid prevent us from seeing the surface of the planet through telescopes, but space probes have used radar to map the planet surface revealing mountains and highland areas surrounded by large, flat deserts of broken and eroded rocks.



• The gas clouds reflect sunlight so well, Venus appear in our sky as a brilliant object; only the Sun and Moon are brighter. Because Venus lies between Earth and the Sun, like Mercury it is always seen farily close to the Sun in our sky. Depending on whether it is visible just before sunrise or sometimes just after sunset, it is sometimes described as the "morning star" or the "evening star" (though it is, of course, a planet and not a star at all).



• Astronomers think Venus has a core containing iron, but details of what it might be like are not known. The core is surrounded by a rocky mantle.



• The surface has been photographed by Soviet space probes that landed on Venus, and a thimbleful of Venusian soil was automatically analyzed by one of them. The sample was found to contain calcium, sodium, silicon, iron, magnesium and potassium.



• The atmosphere of Venus consists of carbon dioxide gas containing clouds of sulphuric acid. The atmosphere is about 150 miles (250 km) deep, but most of the gas is concentrated in the lowest 17 miles (28 km).



• The carbon dioxide acts like a greenhouse, trapping the Sun's heat so that the surface temperature reaches 900�F(480�C) and never falls below 810�F(430�C).

Space Probes that have gone to Venus

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