Find when Google update imagery in your area

Google now offers a way to be notified when imagery is updated in any given part of the world for both their Google Maps and Google Earth applications. 

Google Earth Engine: A planetary-scale platform for environmental data & analysis

Google Earth Engine brings together the world's satellite imagery—trillions of scientific measurements dating back more than 25 years—and makes it available online with tools for scientists, independent researchers, and nations to mine this massive warehouse of data to detect changes, map trends and quantify differences to the earth's surface.