Predictors show you how your astrology modifiers will change in the next 20, 40, and 60 minutes. There is one predictor for each modifier, and they can be bought from players/bots or from Urania in Arius City for 80 gold coins each. To see the predictions, you must "use" the stone, after which the stone will disappear. In general, a green bar means "good", and an orange bar means "bad". If you want to know what your modifiers currently are, you can use the respective indicator.
The astrology predictors currently in the game are: