NASA's Astronomy Picture of the Day entry for Aug. 2, 2026 featured a fire rainbow photographed in 2021 near North Fork Mountain in West Virginia, USA. The image is credited to Christa Harbig.

The phenomenon, informally called a fire rainbow for its flame-like appearance, is a circumhorizon arc, which appears parallel to the horizon. According to the accompanying explanation, the arc requires the Sun to be at least 58 degrees high in a sky where cirrus clouds, in this case cirrus fibratus, are present below. The numerous flat, hexagonal ice crystals making up the cirrus cloud must be aligned horizontally so they refract sunlight in a collectively similar way.

Because of these conditions, circumhorizontal arcs are described as somewhat unusual to see. The entry lists Robert Nemiroff, Jerry Bonnell, Cecilia Chirenti and Keighley Rockcliffe as authors and editors.