Planet Phases Part 2
This is a small modification compared to Planet Phases Part 1. Here I plotted a brightness parameter curve which moves with the periodicity of one planet's year. The brightness maximum is between conjuction and maximum elongation. In the points of maximum elongation the phase has exactly 50% illumination, in conjunction 0%. The maximum brightness is inbetween, because the size appears bigger than in maximum elongation due to the shorter distance between the earth and the planet.
Remark: I found that the movement is rather humpy. If you want to have it run more smoothly, go to "copy and share" at the bottom and download the worksheet to your hard disc. 100% virus free :-)