Residents in Singapore were treated to a truly unusual phenomenon, as a so-called fire rainbow lit up the sky in the city-state.
Many people posted stunning photos on social media of the rare spectacle.
NASA says that fire rainbows are actually called circumhorizon arcs, which are created by a unique set of circumstances.
A spokesman said: "The sun must be at least 58 degrees high in a sky where cirrus clouds are present.
"Furthermore, the numerous, flat, hexagonal ice-crystals that compose the cirrus cloud must be aligned horizontally to properly refract sunlight like a single gigantic prism.
"Therefore, circumhorizon arcs are quite unusual to see."