As an oil slick in the Gulf of Mexico came within 20 miles of barrier islands and beaches in Louisiana, the U.S. Coast Guard announced plans to begin setting fire to the leaked oil to reduce the amount that can contaminate ecologically sensitive areas. News reports said that burning could begin Wednesday.
This image of the slick was captured on Tuesday, April 27, 2010, by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite. Although the slick is less obvious than it was in earlier images, that is not necessarily a sign that it is smaller or more dispersed. The ability to detect oil slicks in photo-like satellite images is very sensitive to the viewing geometry—the angles between the surface, the Sun, and the satellite—at the time of the image. If the slick happens to be located in the sunglint part of the image, it may be very visible, but if not, it can be faint or even impossible to see.