Dendrochronology (word derived from Greek , "dendron", "tree limb"; , "khronos", "time"; and , "-logia") was developed during the first half of the 20th century originally by the astronomer A.E. Douglass, who founded the Laboratory of Tree-Ring Research at the University of Arizona. Douglass researched sunspot activity. He expected changes in solar activity would affect climate patterns on Earth. The climate would be recorded by tree-ring growth patterns.