Astronauts aboard the International Space Station use the Sun’s reflection point to reveal features that are otherwise difficult or impossible to see. Viewed from 290 kilometers (180 miles) above, Earth’s largest river, the Amazon, snakes its way through a floodplain that is more than 32 kilometers (20 miles) wide. Sunglint from the water surface shows the numerous lakes and side tributaries on the floodplain.
The extensive lakes have a longer history to tell. In response to falling sea level during the last Ice Age, the Amazon River cut a canyon tens of meters deep. Sea level rose again with rapid melting of the ice sheets, and to keep pace, the Amazon River bed also has risen. The rising river and bed have filled the canyon with vast quantities of sediment from the distant Andes Mountains in the process. The persistence of the lake depressions shows that this filling process is not yet complete.
Numerous lighter-toned patches of deforestation dot the left margin of the image. Small, bright red patches on either side of the floodplain are open-cast mines where the red soils that underlie the rainforest are exposed.
You can view another more detailed sunglint image showing Lago do Erepecu (immediately north of this image) and the red soils of the rainforest by clicking here. A dramatic panorama of the Amazon River and its vast floodplain can be viewed here.
Astronaut photograph ISS040-E-103491 was acquired on August 19, 2014, with a Nikon D3S 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 the Expedition 40 crew. It 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, Jacobs at NASA-JSC.