Regarding the Planet puzzle

[xFingersx]

I've come up with these thoughts so far...

1. Planets marked with roman numerals must be clicked in order.
2. Crossing paths is not allowed.
3. All planets must be used.

I am unsure of the significance of the following...

1. You are able to cross through planets without clicking them.
2. Do the colors matter?
3. Does even touching (without going through the center) of a planet count as a crossed path?

This will continue to ruin my day, until I finish these trials because I am a puzzle fiend...