Among all the planets of the solar system, Venus is the brightest and hottest of all. As its orbit is inside the orbit of the Earth, it is closer to the Sun and never gets very far from it. Though it is a planet, Venus is popularly known as the ‘Evening Star’, when it appears in the western sky for a short time after the sunset, as the first star in the deepening twilight. It is also known as the ‘Morning Star’, which becomes visible in the eastern sky, shortly before the sunrise, as the last star in the still darken firmament.
Venus has a very dense atmosphere, which obscures its surface from one’s view. Since the surface is not visible, we know very little about the conditions below the cover of the ‘clouds’. Venus is the hottest among all the planets of the solar system. The extremely hot temperature of the planet is actually, caused by the density of its atmosphere, 91% of which is made up of carbon dioxide. It creates a ‘green house effect’ on the planet, and like a cover of glass it allows entry of sun’s rays (which come in short waves), but does not allow the heat to escape (which is emitted as long waves), from the ground through it. The major part of the heat is absorbed by carbon dioxide, which in turn radiates some of the heat to the ground. Thus the atmosphere, by trapping the heat, raises the surface temperature to about 500ºC.
Venus is known as the ‘twin of the Earth’, because of its close proximity to the Earth in size, mass an density. However, Venus is far more hot than the Earth, as its reflecting capability (albedo) is as high as 171. To put it differently, Venus reflects 71% of the light it receives from the Sun. Because of its high albedo, Venus is the third brightest object. in the sky, after the Sun and the Moon. The Moon’s albedo is only 7, but it looks brighter. Although Saturn, Uranus and Neptune have more reflecting power than Venus, they do not appear brighter, owing to their distance.