On June 22, 2026, NASA\u2019s PACE (Plankton, Aerosol, Cloud, ocean Ecosystem) satellite captured a stunning image of the Black Sea glowing vivid turquoise using its Ocean Color Instrument (OCI). The satellite, launched in February 2024, is designed specifically to observe ocean biology at a level of detail never before possible from space. The image shows swirling patterns of bright blue water stretching across hundreds of kilometers of the sea\u2019s surface, a seasonal display that recurs each spring and summer but varies dramatically in intensity and location.
The striking turquoise color is caused by massive blooms of coccolithophores, microscopic phytoplankton that coat themselves in tiny plates of calcium carbonate, similar in composition to chalk or seashells. When these organisms multiply in enormous numbers during late spring and early summer, their reflective shells scatter sunlight in a phenomenon known as backscattering, giving the ocean a milky turquoise appearance visible from orbit. Individual coccolithophores are far too small to see without a microscope — thousands would fit on the head of a pin — but their collective blooms can cover entire sea basins.
An astronaut aboard the International Space Station also photographed the bloom from a different perspective on May 27, 2026, capturing it as it extended through the Bosphorus strait into the Sea of Marmara. In the photograph, swirling currents are traced by the glowing phytoplankton, revealing the complex water dynamics where the Black Sea meets the Mediterranean corridor. These blooms play a vital role in Earths carbon cycle: as coccolithophores grow, they absorb carbon dioxide from the atmosphere, and when they die, their calcium carbonate shells sink to the seafloor, locking that carbon away in sediment for geological timescales.
Knowledge takeaway: NASA\u2019s PACE satellite observed the Black Sea turning turquoise on June 22, 2026, caused by blooms of coccolithophores — microscopic phytoplankton with calcium carbonate shells that scatter sunlight; the bloom extended through the Bosphorus and was photographed by ISS astronauts; these organisms play a significant role in the ocean carbon cycle by sequestering CO2 in deep-sea sediments over geological timescales.