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A newly released satellite image of Egypt’s Nile river shows the river colored deep red, bringing to mind the biblical first plague in which the waters of the great river turned to blood. But, this time at least, it is not the wrath of god that is responsible for the river’s crimson hue: The European Space Agency’s Sentinel-3A satellite, which took the picture, uses a radiometer to measure infrared energy. The heat radiated by vegetation around the river is therefore responsible for the red color. The satellite, launched in February, is designed to monitor environmental changes. It is the third of more than a dozen “eyes in the sky” that make up the Copernicus program, which the ESA describes as the most sophisticated Earth observation system ever launched. 
The First Plague: Water Is Changed into Blood, by 19th century French painter James Tissot (Wikipedia) Two satellites already in orbit are equipped with radar and high-resolution cameras, to which Sentinel-3A adds instruments for measuring sea and surface temperatures, among other things. 
A view of the Nile River. (CC-BY plusgood, Flickr.com) The satellite will be able to spot upcoming droughts by detecting subtle changes in surface color that suggests crops are failing. One of Sentinel-3A’s greatest advantages is its ability to scan the entire planet in just over a day and send back data within hours, giving scientists and policy-makers detailed information on environmental changes in close to real time. By measuring sea temperatures it will boost short-term weather forecasts and help track the impact of climate change. AP contributed to this report. |
