Billows of light greens and blues spanning hundreds of kilometers brightened the waters of the Celtic Sea in spring 2024. Phytoplankton blooms often appear in northern seas as surface waters grow warmer and receive more sunlight in the spring. Satellites glimpsed the emergence of this colorful area for over a week before the MODIS (Moderate Resolution Imaging Spectroradiometer) on NASA's Aqua satellite acquired this natural-color image on May 10. Phytoplankton are tiny, plant-like organisms that often float near the ocean surface. With enough carbon dioxide, sunlight, and nutrients, they can grow in massive numbers. In turn, they form the foundation of the aquatic food web, feeding everything from microscopic zooplankton to shellfish to finfish