Noctilucent clouds, also known as night-shining clouds, were observed over Estonia's capital, Tallinn, early on Friday, July 17, 2026, Forbes reported, citing a photograph by AP Photo/Sergei Grits.
According to SpaceWeather.com, observers are recording bright electric-blue formations across the northern region of Europe. These clouds form at altitudes between 76 and 85 kilometers in the mesosphere, the Earth's highest atmospheric layer, where temperatures drop to minus 120 degrees Celsius.
As per a Forbes article dated July 20, 2026, the clouds are composed of tiny ice crystals that form around microscopic dust particles from meteoroids. This dust, left behind by burning meteoroids, acts as nuclei for the crystals, creating the characteristic shimmering blue and silver patterns.
The season for these clouds peaks in June and July when water vapor rises into the mesosphere and freezes onto meteor dust particles. Observations are possible at latitudes from 50 to 70 degrees North, including Northern Europe, Canada, and Alaska, as well as parts of the northern United States.
The best time for observation is 60–90 minutes after sunset or before sunrise, when the sun's rays illuminate the clouds while remaining below the horizon for the observer on the ground. The clouds are visible low on the northern horizon in clear skies as thin, wavy streaks, without the need for special equipment.
Similar observations have been recorded in Vilnius, Lithuania, and on the northeast coast of England, where the clouds have also been described as the highest in Earth's atmosphere. Forbes notes that the season lasts from late May to early August.
A Forbes article from July 20, 2026, documents the return of one of the most unusual summer astronomical phenomena, confirmed by photographs and observer reports.
