Few people have ever claimed to see three rainbows arcing through the sky at once. In fact, scientific reports of these phenomena, called tertiary rainbows, were so rare — only five in 250 years — that until now many scientists believed sightings were as fanciful as Leprechaun’s gold at a rainbow’s end. These legendary optical rarities, caused by three reflections of each light ray within a raindrop, have finally been confirmed, thanks to photographic perseverance and a new meteorological model that provides the scientific underpinnings to find them.
Although staggeringly rare, tertiary and quaternary rainbows are natural products of the combination of refraction, dispersion, and reflection inside raindrops.
Source: Science Daily
Neat. This is exciting in that what was assumed to be questionable has finally been confirmed. Discoveries in science are intertwined with improvements in technology that allow us to see things we could not previously. Check out the link for pictures.