Venus-the Clouded Planet

Venus, our nearest planetary neighbour, only 40 million km away, has its surface hidden from view by a dense yellowish-white cloud, which extends to 80 km  above the surface (Fig).  Venus appears to be the third brightest object in the sky after the Sun and the Moon, because of  its short distance from us and because the white cloud reflects almost 76 per cent of  the sunlight that falls on it. Venus appears so bright at times that, under ideal atmospheric conditions,  it may be seen with the unaided eye  in daytime. Venus can be best seen about three hours after sunset when it is a night object or  about three  hours before sunrise when it  is a morning obiect. As you have  read in Unit 9, Venus appears to go through phases, quite hke those oi  the Moon. It requires almost 20 months for an observer to see Venus in all its phases. As  revealed from the space probes, Venus has turned out to be a broiling hot planet. The surface temperatures of Venus are around 480°C. The atmosphere of Venus is made up of  96 per cent carbon dioxide gas and clouds of  sulphuric acid withsmall quantities of hydrochloric and hydrofluoric acid. There we small traces of water vapour, nitrogen, argon, sulphur dioxide and carbon monoxide gases. The atmospheric pressure is 90 times the pressure we feel from the Earth's atmosphere. With its searing heat, crushing pressures and poisonous gases, Venus seems  less the goddess of love of mythology and more an incarnation of hell! Life cannot survive on Venus. The high surface temperat%e of Venus comes about through what is known as  the greenhouse effect. Sunlight passes through the clouds and atmosphere of Venus, and reaches its surface. The suqace on being heated, gives out infrared radiations. The carbon dioxide in the atmosphere of  Venus does not let the infrared radiation escape. Thus, the heat of  the Sun is efficiently trapped with only very little being able to escape. As a result,  the surface temperature rises.