Earth is a complex, dynamic system we do not fully understand. To learn more about it, NASA, as the agency with access to space, was tasked with launching the first weather satellite back in 1960. Today, NASA uses satellites, aircraft and even an occasional boat to study our planet's air, land and water. It's called "Earth System Science" and we are trying to answer some big questions: How is the global Earth system changing? What causes these changes? How will Earth change in the future? And what we learn benefits society through applications such as weather forecasting, freshwater availability and disaster response.