An astonishing 82 percent decrease in the cost of solar photovoltaic (PV) energy since 2010 has given the world a fighting chance to build a zero-emissions energy system which might be less costly than the fossil-fueled system it replaces.

Computer-generated satellite "photos" can be very difficult for humans and other machine learning algorithms to detect, a growing concern of national security officials who fear that doctored images might find their way into troops' hands or be used to sway public opinion. But help may be on the way.