That rainbow circle of light you might glimpse in the sky out an airplane window is known as a glory. For the first time, astronomers have fully imaged one on another planet.
Glories occur at a point in the sky opposite the sun when light scatters off tiny liquid particles, usually water in our clouds, refracting into rings. After analyzing this view of a glory on Venus — combining three wavelengths into a false-color image — astronomers were surprised to learn that the planet’s clouds aren’t pure sulfuric acid after all, but may include iron chloride and pure sulfur.