ABSTRACT
Venus, the second planet in order of distance from the Sun, is almost a twin of the Earth in size and mass. Venus is the brightest object in the sky apart from the Sun and the Moon. Venus must have been known since prehistoric times. Venus moves round the Sun in a practically circular orbit. Its elongation can be as much as 47°, so that it can be above the horizon from as much as 512 hours after sunset or before sunrise; phenomena for the period 2000–2015. In 1721, Edmond Halley was the first to note that Venus, unlike Mercury, is at its brightest during the crescent stage, when about 30% of the daylight hemisphere is turned in our direction. Early telescopic observers were unable to see any genuine details on Venus, but on 9 January 1643 G. Riccioli recorded the Ashen Light, or faint visibility of the night side of Venus.
