English: The arid Kalahari Desert sweeps across most of Botswana as well as parts of Namibia, Angola, Zambia, and South Africa. About 2 million years ago, however, the portion of of the Kalahari in northern Botswana was covered by one of the largest inland seas in the world. Roughly 10,000 years ago changes in the flow of the water and advent of a dryer climate led to the slow destruction of the lake. Today, the last vestiges of the ancient superlake are the mineral-encrusted and shallow ephemeral lakes known as the Makgadikgadi Salt Pans. These bright-white salt pans span an area of about 10,000 square miles (30,000 square km) in the arid desert and dry savanna in Botswana.

Most of the year these salt pans are crusted in minerals as the parching sun drives evaporation, often leaving just a hint of moisture underlying the thick layer of salt. When the rains come—usually from November to March—water flows in from several rivers, bringing a flush of life-giving water to the Makgadikgadi Pans. Fresh water fills ephemeral ponds and watering holes, creates shallow lakes, nurtures the abundant growth of grasses, and lowers the salinity of the Pans. The refreshing rains and renewal of the Pans also draws large numbers of wildebeest and zebra as well as spurs the arrival of large numbers of flamingo, which breed and raise their young in the wet-season abundance of the Makgadikgadi pans.

On June 27, 2021, the Moderate Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra satellite acquired a false-color image of the Makgadikgadi Salt Pans. This combination of MODIS bands (7,2,1) uses infrared and visible light and aids in separating water from vegetation. In this band combination, vegetation appears electric green, water looks blue, and open land appears tan. Cloud may look white or, if carrying substantial moisture, may be tinted with pale blue.

Although almost three months into the dry season, open water remains in several areas although most of the area is covered in crusted salt. While this image is interesting on its own and illustrates the ongoing annual evaporation of water during the dry season, much more information about the exact nature of the change over time can be gained by comparing two images. Fortunately, the NASA Worldview app can allow us to easily view a pair of images. To see a roll-over comparison of a false-color Terra MODIS image of the Makgadikgadi Salt Pans collected on January 4, 2021, when the wet season was in full swing, with the image acquired well into the dry season on June 27, click here

The NASA Worldview app provides a satellite's perspective of the planet as it looks today and as it has in the past through daily satellite images. Worldview is part of NASA’s Earth Observing System Data and Information System. EOSDIS makes the agency's large repository of data accessible and freely available to the public.