Extraordinary colors in Libya’s sand dunes, as captured by Sentinel-2A. (Photo: ESA)
Right now, high above us, are a suite of satellites called Sentinels. Operated by the European Space Agency, they are circling the earth with one mission: to monitor the earth’s environment. They can capture a precise picture of our planet, down to types of vegetation and sea surface temperatures.
The Sentinels do this through radar and multi-spectral imaging. For example, the Sentinel-2A uses infrared bands to assess types of vegetation and chlorophyll content. (This also gives some of its images unexpected areas of bright red).
The data that the Sentinels collect has a fundamental application for climate change. For example, in February, March and April 2016, Sentinel-1A captured three radar images of Greenland’s northeast coast. The recently-released composite is a vividly detailed, half monochrome, half rainbow image.
A composite image of the north-east of Greenland. (Photo: ESA)
But it tells a story beyond that as well. The rainbow colors indicate the changes in sea-ice during the three-month period. The same satellite is monitoring in near-real time Greenland’s Zachariae Isstrom glacier, in the image at center-left, such is the state of its erosion by warmer water.
To a scientist, the images provide essential information; to a regular person, they are strikingly beautiful, showing mosaics of irrigation, infrared farms and iridescent reefs. Here is a section of the startling satellite art:
A false-color image from Sentinel-2A of southern Mongolia. The shades of red represent different types of vegetation. The turquoise circle at the top is a saline lake, Taatsiin Tsagaan Lake. (Photo: ESA)
The desert in Egypt. The red at the bottom of the image indicates intensive farming along the Nile river. (Photo: ESA)
A image from the Sentinel-2A satellite, with infrared showing a central-pivot irrigation system in Saudi Arabia. (Photo: ESA)
A true-color image of coral reefs in the Red Sea of Saudi Arabia. (Photo: ESA)
A multi-temporal radar image from Sentinel-1A of the Aral Sea in Central Asia. The name is something of a misnomer: the sea has largely dried up. (Photo: ESA)
Lake Amadeus in Australia’s Northern Territory. (Photo: ESA)
Dasht-e Kavir, Iran’s salt desert, pictured with a combination of Sentinel-1A radar scans. (Photo: ESA)
Central California seen through Sentinel-1A’s radar, with the San Andreas fault line running diagonally down from top left. (Photo: ESA)
A true-color image of Namibia’s Namib-Naukluft National Park, with orange-red sand dunes. (Photo: ESA)
An algae bloom in the Baltic Sea, as pictured by Sentinel-2A. A boat cuts down from the top of the image. (Photo: ESA)
The dusty shades of the Sahara desert, in Algeria. (Photo: ESA)
Yuma, Arizona, from Sentinel-2A. The different shades of red show the different chlorophyll content between the farms (the squares) and the irrigation system (the circles). (Photo: ESA)
Canada’s Manicouagan Crater, which was created by an asteroid strike. In this false-color radar image, the blue is areas of ice and water and the yellows and oranges are vegetation. (Photo: ESA)