By The European Times | Created at 2026-07-22 05:26:53 | Updated at 2026-08-04 12:47:30
1 week ago
Every year in late spring and early summer, the Black Sea changes its usual dark color and in places acquires a striking turquoise hue. The phenomenon is so large-scale that it is clearly visible from space, and this year it was captured by NASA’s PACE satellite.
On June 22, the PACE (Plankton, Aerosol, Cloud, Ocean Ecosystem) satellite recorded the seasonal phenomenon using its Ocean Color Instrument (OCI). The resulting images show vast milky-blue and turquoise areas on the surface of the Black Sea. According to NASA Earth Observatory, this is a natural process that is observed almost every year.
Scientists explain that the unusual coloring is due to the mass reproduction of coccolithophores – microscopic organisms from the phytoplankton group. They are covered with tiny plates of calcium carbonate that strongly reflect sunlight. When their population increases sharply in late spring and early summer, the water takes on a characteristic milky-turquoise color that can be observed even from orbit.
During the rest of the year, other microscopic algae, diatoms, dominate the Black Sea, which darken the water.
The seasonal bloom has also spread to the Bosphorus, the strait that connects the Black and Marmara Seas. On May 27, nearly a month before the PACE image, an astronaut aboard the International Space Station (ISS) photographed the area where the blooming phytoplankton had formed impressive spiral shapes following the sea currents on both sides of the strait.
Although individual coccolithophores are invisible to the naked eye, when they multiply en masse, they can change the color of vast areas of the sea.
That is why satellite observations are extremely valuable to scientists – they allow us to track the development of marine ecosystems even in areas where sampling is difficult.
In addition to creating impressive views, these microscopic organisms also play an important role in the climate. During their development, they absorb carbon dioxide from the atmosphere and seawater.
After the end of their life cycle, some of the carbon is deposited on the seabed, where it can remain stored for long periods. In this way, coccolithophores participate in the natural carbon cycle on Earth.
The images of the Black Sea are part of the Earth Observation Program of the International Space Station and NASA Earth Observatory, which provides free access to images used by scientists around the world to study the oceans, atmosphere and climate processes.
Source: NASA
