What is happening to this extraordinary formation in the sky? Ice crystals in a distant cirrus cloud move like tiny prisms floating in water. Called a “flame rainbow” because of its flame-like appearance, it can appear as a circle above the horizon. For such an arc to form, the Sun must be at least 58 degrees above the horizon, with cirrus clouds below. The many hexagonal and flat ice crystals inside the cirrus clouds must be aligned horizontally to refract the Sun's light in a similar way. This is why this type of celestial phenomenon is extremely rare. This impressive image was photographed earlier this month near North Fork Mountain in West Virginia, USA.

August 30, 2021 Astronomy Photo of the Day (NASA APOD)

Image Source: Christa Harbig