Time-Based on/off button using sunset/rise not hour-based time

Hiya, i want to use teh on/off button on the bathroom dimmer to select different sceans acording to teh sunset/rise, not by setting hours. I want the sceans to match the natural light of day or night not by fixed hours, becasue the natural light (sunrise/set) changes vastly in winter and summer.

Does any one know if this is possible?