Where is it? Los Glaciares National Park, Argentina [-50.469690266, -73.03391046]
What's in the photo? The point where a non-retreating glacier, a turquoise lake and a murky river meet
Who took the photo? An unnamed astronaut onboard the International Space Station (ISS)
When was it taken? March 2, 2021
This incredible astronaut photo shows the unusual point where a hefty non-retreating glacier, a pristine turquoise lake and a murky green "river" perfectly converge at the intersection of three valleys in Argentina.
The trio of hydrological features — the Perito Moreno Glacier, Lago Argentino and Brazo Rico — lie at the heart of Los Glaciares National Park, which covers an area of around 2,300 square miles (6,000 square kilometers) in the Santa Cruz province of southern Argentina, near the country's border with Chile.
The aerial photo doesn’t just show off these three aqueous entities in a single frame; if you look closely, it also reveals the point where the trio touch in a slim channel along the western edge of the Magallanes Peninsula — the rocky outcrop that lies between the lake and the river, according to NASA's Earth Observatory.
In this photo, the waters of Lago Argentino and Brazo Rico are likely in direct contact with each other (as in the photo below). But their waters do not readily mix because they have different densities, due to their respective concentrations of suspended particulate matter, according to a 2022 study.
But every four to five years, the glacier's tongue juts forward, colliding with the Magallanes Peninsula and temporarily damming the Brazo Rico. When this happens, the surface of the murky body of water rises by up to 100 feet (30 meters) until a pressure build-up causes the icy dam to spectacularly "rupture," the Earth Observatory previously reported.
Perito Moreno is the largest glacier in Patagonia, which includes parts of Argentina and Chile. It is approximately 19 miles (30 km) long with ice up to 200 feet (60 m) thick. In total, the glacier holds roughly the same amount of water as 360,000 Olympic swimming pools, according to back-of-the-envelope calculations.
The glacier is "non-retreating," meaning that it is not shrinking despite rising atmospheric temperatures triggered by human-caused climate change. This is extremely rare nowadays, and Perito Moreno is frequently cited as one of the "world's last major non-retreating glaciers." However, a recent study hints that it may finally be starting to shrink.
Lago Argentino is the largest freshwater lake in Argentina, covering a total area of around 550 square miles (1,425 square km). The section visible in the astronaut photo is the lake's southernmost arm. It contains glacial meltwater filled with rocky particles released by the glaciers' constant movements, collectively known as "glacier milk," which gives the water its striking turquoise color.
The lake's northernmost arm also connects to the Upsala Glacier, which is currently in full retreat.
Brazo Rico, meaning "rich arm" in Spanish, is also technically part of Lago Argentino. However, it has become increasingly isolated from the rest of the lake due to repeated damming by the Perito Moreno glacier, making it behave more like a river than part of a lake.
The frequent icy obstruction is also responsible for Brazo Rico's insipid color, which is the result of sediment dislodged by its movements. The continued rising and falling of the river's surface has also carved out a border around its edges where no trees can grow.
Eagle-eyed viewers may have also spotted the narrow road winding across the Magallanes Peninsula and along the Brazo Rico's northern edge (just above the tree line): One can only imagine the extraordinary views you'd get to experience driving along there.
For more incredible satellite photos and astronaut images, check out our Earth from space archives.
