A project the University of Arizona and Biosphere 2 is calling the 'World's Largest Earth Science Experiment" kicks off today.
Called the Landscape Evolution Observatory, or LEO, it is the world's only artificial watershed. LEO is located inside Biosphere 2 in Oracle.
At 2 PM today an opening ceremony takes place at Biosphere 2. During this ceremony the LEO project will experience its first artificial rain.
For more information on the LEO project click here.