If you track the relative positions of Earth and Venus over an 8 year period, this is the resulting pattern.
It’s created by two points of different radii moving at different speeds around a fixed point. The fixed point is the sun and the speeds of the variable points is dependent on the mass of the chosen planets. Altering the relative distance or speed between the points would produce a different pattern and at certain intervals would produce symmetrical patterns.
Mathematically, this is pretty cool though. It allows us to see something that we would assume is a humanly-created piece of art via the natural movements and mathmatics in our universe.