 Venus , with an orbit inclined by 3 @.@ 4 ° relative to the Earth 's , usually appears to pass under ( or over ) the Sun at inferior conjunction . A transit occurs when Venus reaches conjunction with the Sun at or near one of its nodes — the longitude where Venus passes through the Earth 's orbital plane ( the ecliptic ) — and appears to pass directly across the Sun . Although the inclination between these two orbital planes is only 3 @.@ 4 ° , Venus can be as far as 9 @.@ 6 ° from the Sun when viewed from the Earth at inferior conjunction . Since the angular diameter of the Sun is about half a degree , Venus may appear to pass above or below the Sun by more than 18 solar diameters during an ordinary conjunction . 
