Oil from the Deepwater Horizon rig lingered near the Mississippi Delta on June 10, 2010. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite captured this image the same day. The oil slick is pale gray, and the most conspicuous portion of the oil slick in this image appears near the Deepwater Horizon rig. A smaller, though still sizable, extension of the slick appears northeast of the rig. Clouds somewhat obscure the Mississippi Delta, northwest of the rig.
In photo-like satellite images, the mirror-like reflection of the Sun off the ocean surface makes the oil slick easier to see. Normally, waves blur the perfect reflection of the Sun into a wide, washed-out strip. Oil smoothes the surface of the water, making it a better mirror. Depending on the location of the oil, the angle of the Sun, and the satellite’s angle of view, the oil may appear brighter or darker than the surrounding oil-free surface waters.