A tongue of ice reaching the land

The heavily textured surface of Perito Moreno, one of the world’s last remaining glaciers, sparkles in this detailed photograph taken by an astronaut on the International Space Station (ISS). The glacier, located at the southern end of the southern Patagonia Icefield in Argentina, rises more than 60 meters (200 feet) above the surface of Lago Argentino to the northeast. It marks the point of separation between the main lake and its more murky southern branch, Brazo Rico. A single road winds along the coast of the Magallanes peninsula towards Moreno.

The surface of Perito Moreno is marked by a mixture of glacial fissures (crevasses) and ice columns (seracs). These characteristics are the result of the shear stress inside the glacier, as the “river of ice” goes through periods of advance and retreat. Where the glacier meets the lake, the ice separates in a sonic event called calving that occurs almost daily. This spectacle has made Los Glaciares National Park a UNESCO World Heritage Site and a popular tourist destination.

Periodically, Moreno advances to the Magallanes Peninsula, acting as a natural dam and cutting off Brazo Rico from the rest of Lago Argentino. During such times, the water in Brazo Rico becomes muddy and its level rises. While the canal leading to Lago Argentino is open in this photo, evidence of this cyclical process is evident in the higher treeline surrounding Brazo Rico. The rise and fall of the water creates a separator of tub rings between the shore and the lower forest. In contrast, the forests around Lago Argentino extend to the edge of the lake.

The photograph of astronaut ISS064-E-39659 was acquired on March 2, 2021 with a Nikon D5 digital camera using a focal length of 1600 millimeters. It is provided by the ISS Crew Earth Observation Facility and the Earth Sciences and Remote Sensing Unit, Johnson Space Center. The image was taken by an Expedition 64 crew member. The image has been cropped and enhanced to improve contrast, and lens artifacts have been removed. The International Space Station program is supporting the laboratory as part of the ISS National Laboratory to help astronauts take photos of Earth that will be of greatest value to scientists and the public, and to render those images available free on the Internet. Additional images taken by astronauts and cosmonauts can be viewed at the NASA / JSC Gateway for Photography of Earth Astronauts. Caption by Alex Stoken, Jacobs, JETS contract at NASA-JSC.

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