Diamond Member SpaceMan 0 Posted Wednesday at 04:01 AM Diamond Member Share Posted Wednesday at 04:01 AM Earth Observatory This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up The Paradox of Lençóis… This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up Topics This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up More Content This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up About This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up A mosaic of hundreds of freshwater lagoons partially filled the troughs around many of the park’s dunes when the This is the hidden content, please Sign In or Sign Up (Operational Land Imager) on This is the hidden content, please Sign In or Sign Up captured this image on June 8, 2026. NASA Earth Observatory/Michala Garrison The coastal dune system in This is the hidden content, please Sign In or Sign Up in northeastern Brazil is among the most surreal landscapes on Earth. At first glance, the park looks like a desert, but it is far from it. This place receives about 125 centimeters (50 inches) of rain per year—slightly more than Seattle and double what falls in London. The result is a paradox: rows of sparkling white quartz dunes, some rising 30 meters (100 feet), soar over a mosaic of blue and green freshwater lagoons. The park’s name stems from the Portuguese word lençóis, meaning “bedsheets,” a reference that makes the most sense when the park is viewed from afar. From that perspective, the sweeping curves of the largest coastal dune field in South America resemble a rumpled, white bedsheet. These This is the hidden content, please Sign In or Sign Up images were captured in June 2026, around the time when lagoon water levels typically peak. The partially impermeable layer of bedrock and clay beneath the sand prevents the lagoons from draining during the wet season. However, as rains subside between August and November, the This is the hidden content, please Sign In or Sign Up falls, and by December, most of the lagoons dry up. This is the hidden content, please Sign In or Sign Up Winds blowing from the northeast created the lines of dunes visible in this detailed view of a portion of the Landsat 9 image shown above. NASA Earth Observatory/Michala Garrison The dune field, a tan area within an expanse of green, is the centerpiece of the park. It spans about 900 square kilometers (350 square miles), roughly the size of New York City. From above, shallower lagoons appear light blue, often taking on turquoise or aquamarine hues as sunlight reflects off the sand below. Deeper lagoons are darker, a result of the deeper water absorbing more red, yellow, and green wavelengths, leaving mostly blue light to scatter back. This is the hidden content, please Sign In or Sign Up , microscopic algae, and This is the hidden content, please Sign In or Sign Up also contribute to the array of colors, giving some lagoons greener and browner tones. Green vegetation surrounds the dune field, which sits at the intersection of three This is the hidden content, please Sign In or Sign Up : the This is the hidden content, please Sign In or Sign Up rainforest to the west, the tropical wooded savannas of the Cerrado to the south, and the dry shrublands and thorn forests of the Caatinga to the east. Closest to the dunes are mangroves and This is the hidden content, please Sign In or Sign Up , ecosystems well adapted to sandy, coastal soils. The dune field exists because of the rare convergence of geologic and climatic conditions. Rivers, including the Mearim and Parnaíba, deliver the key ingredient—quartz sand—to this unusually flat portion of the Maranhão coastline in massive quantities. It has accumulated here over the past few hundred thousand years driven in part by fluctuating sea levels and shoreline This is the hidden content, please Sign In or Sign Up . Persistent easterly trade winds have also played a critical role. During the dry season, winds often reach at least 50 kilometers per hour, fast enough to build the dunes and push them westward at a pace of roughly This is the hidden content, please Sign In or Sign Up per year. That is fast for sand dunes, though not the fastest in the world. Satellites have tracked small barchan dunes in This is the hidden content, please Sign In or Sign Up moving at rates exceeding 80 meters per year. This is the hidden content, please Sign In or Sign Up NASA Earth Observatory/Michala Garrison Landsat images, meanwhile, show the dune field at Lençóis Maranhenses has This is the hidden content, please Sign In or Sign Up by about 0.5 kilometers between 1986 and 2026 in some areas due to the conveyor belt of dunes running inland from the coastline. The nearly constant movement of sand prevents vegetation from becoming established across much of the dune field. UNESCO declared the park a World Heritage site in 2024, This is the hidden content, please Sign In or Sign Up its remarkable geology and rich biodiversity. The park is home to more than 850 documented species, including This is the hidden content, please Sign In or Sign Up , birds, This is the hidden content, please Sign In or Sign Up , mammals, and This is the hidden content, please Sign In or Sign Up . Among them are four endangered species, including the neotropical otter, West Indian manatee, scarlet ibis, and This is the hidden content, please Sign In or Sign Up (a type of wild cat). Among the lagoons’ most remarkable inhabitants are the This is the hidden content, please Sign In or Sign Up (Hoplias malabaricus), a predatory fish species with large canine-like teeth. During the dry season, it burrows far enough under the sand to find damp mud, where it enters a dormant state, emerging after the rains to hunt insects and other fish. NASA Earth Observatory images by Michala Garrison, using Landsat data from the This is the hidden content, please Sign In or Sign Up . Story by Adam Voiland. Downloads This is the hidden content, please Sign In or Sign Up June 8, 2026 JPEG (36.77 MB) References & Resources Atlas Obscura (2020, July 16) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. C.M. de M. Luna, M. (2011) This is the hidden content, please Sign In or Sign Up . Geomorphology, 129(3-4), 215-224. CNN (2022, March 9) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. Global Alliance of National Park (2026) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. This is the hidden content, please Sign In or Sign Up Arts & Culture This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. Luís Silva dos Santos, A., et al. (2019) This is the hidden content, please Sign In or Sign Up . Scientific Reports, 9(7434). Marques, M., et al. (2015) This is the hidden content, please Sign In or Sign Up . Brazilian Journal of Botany, 38, 1–18. Miranda, J.P., et al., (2012) This is the hidden content, please Sign In or Sign Up . ZooKeys, 246, 51-68. National Geographic (2010, July) This is the hidden content, please Sign In or Sign Up Accessed August 4, 2026. Parteli, E.J.R. (2021) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. Revista pesquisa fapesp (2013) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. Smithsonian Magazine (2014, June 20) This is the hidden content, please Sign In or Sign Up ? Accessed August 4, 2026. UNESCO (2024) This is the hidden content, please Sign In or Sign Up . Accessed August 4, 2026. You may also be interested in: Stay up-to-date with the latest content from NASA as we explore the universe and discover more about our home planet. This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up This is the hidden content, please Sign In or Sign Up 3 min read Sites relevant to the start of the American Revolutionary War are interspersed throughout the modern-day Boston metropolitan region. 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