For each earth year (1.1.) a midi event, i.e. a tone, is set or played. Within 4 Earth years there are 5 Venus conjunctions, i.e. Venus is seen from Earth 5 times in line with the Sun. If you think of a large circle (ecliptic), Venus is at 0° with the Sun. The result is a polyrhythm of 5 to 4 or 4 to 5.
The same applies to 8 Earth years. Venus is once in line with the Sun when it is behind the Sun, and once when it is in front of the Sun (also known as Venus Transit). Then the polyrhythm results in 10 to 8 or 8 to 10.