Very cool! I didn't realize that the selected planet mattered for where the new orbit is created initially, but I realized how neat this concept is after discovering that! The funny, brief descriptions of the types of planet add a nice charm to the game too :)
I think a parallax effect on the background stars would be really nice when dragging the screen view around!
I'm not sure how the speed of the newly added planet is determined when you buy it... It seemed like some orbited at a normal pace, but some were very slow or not moving at all. I was worried I had placed them in a "bad" spot initially, because points are awarded per orbit, but they seem to award points regularly despite not having moved much in their orbit, so it's probably a visual bug.
I think the pseudo-chaotic motion of planets nested in several layers of orbits is the most interesting part of this game for sure! I'd love to see something like an area-based buff that you can buy (like a static nebula or something) that encourages you to try to make wild geometric patterns of orbits to make strong planets pass through or stay within a particular global space more often. Or even to buy if you *notice* that your wild solar system makes a particular planet stay almost still relative to the sun. This could give some deeper strategy to the structure of the solar system, beyond what you already have with the "inner orbit" multiplier!