An astronaut looked south from the International Space Station to capture this broad view of the winding, brown Amazon River as it flows east (lower right to upper left) across Brazil. Thin levees mark the main course of the river, with much of the floodplain occupied by lakes. Amazon River water makes the lakes muddy, which is in striking contrast with the dark blue of the Tapajós River.

Amazon water is light brown because it carries vast quantities of fine sediment that is eroded from the high Andes Mountains, more than 2,000 kilometers (1,200 miles) upstream to the west. The water in the Tapajós is clear because it drains out of the low rainforest and carries almost no sediment. The spot where the Tapajós meets the Amazon resembles a great lake or estuary dammed behind a thin levee. Water from the Amazon leaks into the Tapajós here, creating a small delta. This pattern of clear rivers dammed by levees of the muddy Amazon is common.

The city of Santarém sits near the point where the Amazon and the Tapajós meet. Because rivers are the highways of the Amazon basin, Santarém is a major port city. The largest river on Earth (the Amazon) allows ocean-going ships to dock at the city’s port even though the port lies 600 kilometers (400 miles) from the Atlantic Ocean. In 2003, the port facility was enhanced to allow for soybean processing. The result has been a change in local land use from pasture to soy farming. The deforested zones of farms and cattle pasture appear on both sides of the image. Santarém also has river access to hundreds of miles of forest to the south via the Tapajós River.

Astronaut photograph ISS044-E-92338 was acquired on September 8, 2015, with a Nikon D4 digital camera using a 70 millimeter lens, and is provided by the ISS Crew Earth Observations Facility and the Earth Science and Remote Sensing Unit, Johnson Space Center. The image was taken by a member of the Expedition 44 crew. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station Program supports the laboratory as part of the ISS National Lab to help astronauts take pictures of Earth that will be of the greatest value to scientists and the public, and to make those images freely available on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA/JSC Gateway to Astronaut Photography of Earth. Caption by M. Justin Wilkinson, Texas State University, Jacobs Contract at NASA-JSC.