Noctilucent clouds are visible in the months of and surrounding summertime in the Northern Hemisphere. To spot the clouds, you must be looking west 30-60 minutes after sunset or east 30-60 minutes before sunrise. The clouds appear as silvery blue wisps, and are comprised of water ice that has settled on meteor dust in Earth's mesosphere. This image was captured in 2016 over Varbla, Estonia by Helkivad Ööpilved.