Very nice. I have only a tiny suggestion: maybe add some tooltips so that if we (desktop users) hover the mouse over, say, The Sun, some facts pop up, like how many pixels wide is this, and such.
Needs a way to easily get back to the start. I accidentally clicked something on screen that took me out beyond the orbit of Jupiter. Trying to scroll back to the start will take forever!
Other than that, nice work!
Not sure if something has changed since you left this comment, but the astrological / alchemical symbols at the top of the page are links directly to the sun and each of the planets.