Remote sensing helps us gauge how human activities are affecting the planet by documenting the destruction of rain forests, monitoring water temperatures in the ocean, and measuring the warming of the Earth's atmosphere. Scientists can also observe some amazing things about crops from a satellite image taken from thousands of miles away. They can tell whether it's just been planted or if it's ready for harvest, if it's is suffering from a disease or is being attacked by pests. This is extremely helpful to farmers with thousands of acres of crops. Students and teachers use the images produced by environmental satellites as tools to inventory land areas, measure species vitality, and plan for the future.
Geologists use satellites to prospect for minerals or oil.
Each mineral also has its own spectral signature. Weather satellites record cloud patterns and movements which are important predictors of storms. They also measure temperature, moisture in the atmosphere, air pressure, rainfall, and snow depth. The same satellites can track large fires, wildlife outfitted with radio transmitters, glaciers calving into icebergs, and changes in the size of the hole in the ozone layer. Spy satellites keep track of armies and military build-up, pick up signals from secret agents' transmitters, and send secret coded messages.