Going with the incentives for helping newbies presented in
this thread, here's an idea that can be added onto the galaxy system presented there, or it can be used with the current system without adjustment.
Allow people to bet on a planet achieving a certain rank or better. Call it the universal development fund or something. You can place a bet by paying the planet's current score in resources. A bet takes the form of:
I bet x:y:z will reach rank 500.
If x:y:z reaches rank 500, you get paid their new score in each resource.
Limits would be that you can't bet on your own planet, and you can only place a bet on a planet that is for a higher rank than the last one was for. If x:y:z has reached rank 490, and then dropped back to 550, you can't bet 510, or 500, you'd have to bet 499 or better.