English: On September 3, 2023, the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite acquired a true-color image of a beautiful bloom of milky-green phytoplankton peeking through the clouds off the coast of Alaska. The gem-like colors were created by massive numbers of microscopic plant-like organisms (phytoplankton) floating on the surface of the Bering Sea.

Large blooms are common in the Bering Sea especially in spring and autumn. In spring, nutrients and freshened water (from melting ice) are more abundant near the ocean surface, spurring the explosive reproduction that creates blooms so large they are easily seen from space. Phytoplankton populations usually plummet in summertime after exhausting the nutrients in surface waters or falling prey to ocean grazers. By autumn, however, storms and cooler water allow nutrients to mix back to the surface, fueling more blooms.

The milky tint of the bloom suggests that it is likely rich in a type of phytoplankton called coccolithophores. They are covered in tiny calcium carbonate plates, which have a chalk-like appearance and are highly reflective. When present in large numbers coccolithophores can make a bloom look a bit like milk has been spilled on the water’s surface.

The island visible in this image is St. Matthew Island Alaska. Said to be the most remote place in Alaska the island sits about halfway between the United States and Russia’s Far East. This uninhabited island sits more than 180 miles (295 km) from Alaska’s Nunivak Island, and it takes about 24 hours to reach by ship. St Matthew is known as one of the richest seabird nesting colonies on Earth with more than 5 million seabirds nesting during breeding season.