 The first recorded observation of a transit of Venus was made by Jeremiah Horrocks from his home at Carr House in Much <unk> , near Preston in England , on 4 December 1639 ( 24 November under the Julian calendar then in use in England ) . His friend , William <unk> , also observed this transit from <unk> , near Manchester . Kepler had predicted transits in 1631 and 1761 and a near miss in 1639 . Horrocks corrected Kepler 's calculation for the orbit of Venus , realized that transits of Venus would occur in pairs 8 years apart , and so predicted the transit of 1639 . Although he was uncertain of the exact time , he calculated that the transit was to begin at approximately 15 : 00 . Horrocks focused the image of the Sun through a simple telescope onto a piece of paper , where the image could be safely observed . After observing for most of the day , he was lucky to see the transit as clouds obscuring the Sun cleared at about 15 : 15 , just half an hour before sunset . Horrocks ' observations allowed him to make a well @-@ informed guess as to the size of Venus , as well as to make an estimate of the mean distance between the Earth and the Sun — the astronomical unit . He estimated that distance to be 59 @.@ 4 million miles ( 95 @.@ 6 <unk> , 0 @.@ 639 AU ) – about two thirds of the actual distance of 93 million miles ( 149 @.@ 6 million km ) , but a more accurate figure than any suggested up to that time . The observations were not published until 1661 , well after Horrocks 's death . 
