Noctilucent clouds are illuminated by sunlight just after the Sun has set below the horizon

iss074e0784418 (June 29, 2026) --- Noctilucent clouds—polar mesospheric clouds illuminated by sunlight just after the Sun has set below the horizon—are pictured from the International Space Station as it orbited 264 miles above northwest China. These high-altitude clouds are more easily seen from space than from the ground and form when extremely low temperatures freeze water vapor in the mesosphere during summer months at high latitudes. Credit: NASA/Chris Williams