Summer Blooms Beneath the Mesosphere

A field of wild summer flowers in Sweden rears up toward the midnight sky, catching the faint twilight glow. Above them, a vibrant display of noctilucent clouds (NLCs) paints the sky in electric blue. These “night-shining” clouds are Earth’s highest, forming roughly 80 km (50 miles) high in the mesosphere, where they catch the sun’s rays long after darkness has settled on the ground.