How do I figure out what string to use for SetSmartProperty()

I am trying to set an updating vector3 value for a sky smart object "Planet"-'s advanced property: "Planet Rotation" in the editor. I have been trying to use -- sky:SetSmartProperty("Planet Rotation ",0,0,0.2) -- to debug and different variations of Planet Rotation have continued to return nil values. ("sky" is just a variable name for the parent object) How do I find out what string SetSmartProperty wants when using it, and if anyone knows, what is the name I should use for the "Planet Rotation" Smart Property.

-- Update: Planet Rotation is a vector3 which doesn't make much sense but how can I make this value an updating smooth rotation?

UPDATE: Soooooo, the "Planet Rotation" smart property was actually a vector3 -- go figure -- so in terms of scripting I am using a Tick function to increment the value which seems bulky and counterproductive, so if anyone has a better solution please add it!