Mosca is an unincorporated community and a U.S. Post Office in Alamosa County, Colorado, United States. Mosca's population is 1,072 as of the 2020 census. It was named for the nearby Mosca Pass, which was named for the Spanish explorer, Luis de Moscoso Alvarado. The Mosca Post Office has the ZIP Code 81146. It is best known for its proximity to Great Sand Dunes National Park and Preserve.

The Alamosa Solar Generating Plant is a 35.3 MWp (30.0 MWAC) concentrator photovoltaics (CPV) power station, the largest in the world when it was completed, in May 2012. It is currently the world's third largest operating CPV facility. The output is being sold to Public Service of Colorado, a subsidiary of Xcel Energy, under a long term Power Purchase Agreement.