When the Italian physicist Galileo Galilei first observed the planet with a telescope in the early 17th century, he found it showed phases like the Moon, varying from crescent to gibbous to full and vice versa. When Venus is furthest from the Sun in the sky, it shows a half-lit phase, and when it is closest to the Sun in the sky, it shows as a crescent or full phase. This could be possible only if Venus orbited the Sun, and this was among the first observations to clearly contradict the Ptolemaic geocentric model that the Solar System was concentric and centred on Earth.
when the italian physicist galileo galilei first observed the planet with a telescope in the early 17th century he found it showed phases like the moon varying from crescent to gibbous to full and vice versa when venus is furthest from the sun in the sky it shows a half-lit phase and when it is closest to the sun in the sky it shows as a crescent or full phase this could be possible only if venus orbited the sun and this was among the first observations to clearly contradict the ptolemaic geocentric model that the solar system was concentric and centred on earth