The NISAR (NASA-ISRO Synthetic Aperture Radar) Earth-observing satellite’s L-band synthetic aperture radar (SAR) instrument captured this image of the Mississippi River Delta region in southeastern Louisiana on Nov. 29, 2025.
The colors in the image represent varying types of cover, which tend to reflect microwaves from the radar differently. Portions of New Orleans appear green, a sign that the radar’s signals may be scattering from buildings that are oriented at different angles relative to the satellite’s orbit. Parts of the city appear magenta where streets that run parallel to the satellite’s flight track cause the signals to bounce strongly and brightly off buildings and back to the instrument.
The resolution of the image is fine enough to make clear, right of center, the Lake Pontchartrain Causeway — twin bridges that, at nearly 24 miles (39 kilometers) in length, make up the world’s longest continuous bridge over water.
The bright green areas to the west of the Mississippi River, which snakes from Baton Rouge in the upper left to New Orleans in the lower right, are healthy forests. There, tree canopies and other vegetation are causing NISAR’s microwaves to bounce in numerous directions before returning to the satellite. Meanwhile, the yellow-and-magenta-speckled hues of Maurepas Swamp, directly west of …