GALLERY CASTILLO DE LUNA Sergio Conceiçao A rare Blue Moon, the third full Moon in a season with four, glides behind the thematically appropriate Castillo de Luna in Alburquerque, Spain, on August 22, 2021. DETAILS: Canon EOS R6 camera with 400mm lens. Total exposure: 1 /50 second at f/5.6. q VIBRANT NEBULOSITY Emil Andronic Ultraviolet radiation from hot stars within open cluster Berkeley 90 excites the gases of Sharpless 2-115 in Cygnus. Astronomers once thought smaller Abell 71 at the top left was a planetary nebula, later realizing that it's simply a round H II region. DETAILS: Astro-Tech AT106 ED Triplet refractor with ZWO ASI294MM Pro camera. Total exposure: 243/4 hours through narrowband filters. 76 JANUARY 2022 * SKY & TELESCOPE