How Cool Was the Eclipse? Collecting Earth Science Data With Citizen Scientists and GLOBE Observer

During the total solar eclipse of August 21, 2017, the Global Learning and Observations to Benefit the Environment (GLOBE) Program, through the GLOBE Observer app and other means, sought to engage citizen scientists in the shadow of the eclipse by asking them to collect Earth science data, especially about clouds and air temperature, to answer the question, "How Cool is the Eclipse?" The team utilized infrastructure that was already in place, such as existing GLOBE data collection protocols and database, as well as creating new systems and supports using the app and GLOBE Observer website. By leveraging social media (including large NASA accounts), as well as more traditional television, radio and print venues and in-person and virtual outreach events, millions of people potentially heard about the opportunity to help NASA collect data, and tens of thousands downloaded the app. The result was over 20,000 clouds observations and over 80,000 air temperature measurements on the day of the eclipse, from observers in the United States both on and off the path of totality, as well as other nearby countries that only experienced a partial eclipse. Besides exceeding expectations in terms of data collection, the 2017 eclipse provides a test case with valuable lessons learned to apply to future citizen science campaigns during upcoming eclipses in South America in 2019 and 2020, and again in North American in 2024.