A certain form of mysterious shimmering, soaring cloud is starting to appear more often in the night sky, and scientists are working to understand why.
These wispy clouds are so high up in the sky that they reflect the sun’s light even after it’s well over the horizon, giving them an eerie glow in the twilight. Hence their name, noctilucent, meaning “night shining.”
They are often found at the far northern and southern reaches of the planet during their respective summers, although the clouds have occasionally been seen in other locales. They’re visible a couple hours after sunset and before sunrise as iridescent indigo feathers, their ice crystals bending and reflecting fleeting rays.