Why Bill McKibben revived Sun Day — a solar celebration rooted in Colorado

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7min 23sec
President Jimmy Carter on Sun Day 1978
Photo courtesy of the National Renewable Energy Laboratory
This 1978 photos shows President Jimmy Carter paying a visit to the Solar Energy Research Institute (the organization that would later become NREL).

BILL MCKIBBEN AUTHOR ACTIVIST JOURNALIST
Hart Van Denburg/CPR News
Environmental author, journalist and activist Bill McKibben at the CPR News studios in Denver, Sept. 23, 2025.

An organizer wears a solar panel costume at a Denver Sun Day event
Sam Brasch/CPR News

Jimmy Carter on Sun Day 1978
Photo courtesy of the National Renewable Energy Laboratory