Venus is the second planet from the Sun and the sixth largest. Venus' orbit is the most nearly 
circular of that of any planet, with an eccentricity of less than 1%.   

Venus has been known since prehistoric times. It is the brightest object in the sky except for the 
Sun and the Moon. Like Mercury, it was popularly thought to be two separate bodies: Eosphorus 
as the morning star and Hesperus as the evening star, but the Greek astronomers knew better. 
(Venus's apparition as the morning star is also sometimes called Lucifer.)

Since Venus is an inferior planet, it shows phases when viewed with a telescope from the 
perspective of Earth. Galileo's observation of this phenomenon was important evidence in favor of 
Copernicus's heliocentric theory of the solar system.