/** This program plots the apparent position of Venus as seen from Earth. The pattern of Venus's orbit as seen from earth seems to *almost* repeat 5 times every 8 Earth years. However, during that 8 Earth years, Venus actually completes 13 orbits around the Sun. Successively better approximations to this 8/13 ratio can be found by: use continuedFraction.frink formatTable[approximationsWithErrors[venusyear/earthyear, 20]] */ use planets.frink g = new graphics p = new polyline // Draw Earth 100x normal diameter g.fillEllipseCenter[0,0,200 earthradius/m, 200 earthradius/m] for date = now[] to now[] + 8 years step day { [x, y, z, dist, L0, L, B, R] = pos = Planet.Earth.apparentPosition[date, Planet.Venus] p.addPoint[x/m, y/m] // Divide by meters cuz we don't want to plot to actual size. // println[pos] } g.add[p] g.write["VenusApparent.svg", 800, 800] g.write["VenusApparent.png", 1000, 1000] g.show[]