The spectacular image above was taken by one of the European Space Agency's Copernicus Sentinel satellites. Here is ESA's explanation of what we are seeing:
The Upsala Glacier in Argentina’s Los Glaciares National Park is pictured in this Sentinel-2A image from 22 January 2016.
The park was named a UNESCO World Heritage site in 1981 and is the largest in the country, covering an area of over 7000 sq km.
Many glaciers in the national park and in the wider Patagonian Ice Field
have been retreating during the last 50 years because of rising
temperatures. Upsala Glacier has retreated more than 3 km in the past 15
years.
Glaciers are the largest reservoirs of freshwater on our planet, and
their melting or growing is one of the best indicators of climate
change. Satellite data can help to monitor changes in glacier mass and,
subsequently, their contribution to rising sea levels.
Taking a closer look at the terminus of the Upsala Glacier, we can see
how icebergs have broken off and are floating in the water of the upper
reaches of Lake Argentino. The lake’s unique colour is attributed to
‘glacier milk’ – suspended fine sediment produced by the abrasion of
glaciers rubbing against rock.
The darker lines following the flow of the glacier are moraines:
accumulations of rock, soil and other debris – including glacial milk –
that have been deposited by the glacier.
And speaking of the Copernicus Sentinel satellites, ESA has a scare the other day when a small piece of
space debris hit a Sentinel 1-A satellite. The before and after pictures are provided below. Fortunately, the satellite continued with normal operations. The debris was thought to be only about 1 millimeter in size. ESA's Head of Space Debris Office Holger Krag noted:
Such hits, caused by particles of millimetre size, are not unexpected...These very small objects are not trackable from the ground, because
only objects greater than about 5 cm can usually be tracked and, thus,
avoided by manoeuvring the satellites.
