Going (Really, Really) Green: Earth's Plant Life, as Seen From Space
Satellite images of vegetation can help to forecast droughts and fires and even diseases.
The Earth is the "Blue Planet" because more than 70 percent of its surface is covered in water. But what does the Blue Planet look like without the blue? How would Earth appear as ... the Green Planet?
Something like this, apparently. The Suomi NPP satellite, NASA's Earth-observing research satellite, has been gathering data about the world's vegetation from its delightfully lofty perch. The data themselves come from Suomi NPP's Visible-Infrared Imager/Radiometer Suite, or VIIRS, instrument. VIIRS, as its name (sort of) suggests, is able to detect changes in the reflection of light -- which allows it, in turn, to capture images that measure vegetation changes over time. (In order to power photosynthesis, vegetation absorbs visible light, and leaf cells strongly reflect near-infrared light -- which means that lush areas of the planet show less visible light and more near-infrared light than their relatively barren counterparts.)
The Suomi satellite operates as a partnership between NASA and the National Oceanic and Atmospheric Administration. So NOAA did something great: It compiled the past year's worth of Suomi/VIIRS data into a series of striking images. The composite mosaics, stripped of everything but plant life, depict the world as, in a very real sense, a greenhouse.
The images, like almost all such taken-from-space images of Earth, aren't just pretty pictures. The weekly mosaics provided by the Suomi satellite allow researchers to track the changes in the Earth's vegetation over time. And those changes, in turn, can forecast things like droughts and wildfires -- and even outbreaks of diseases. "As vegetation grows in sub-Saharan Africa, so does the risk for malaria," NOAA notes. "Vegetation indexes provide world health organisations the lead time needed to distribute supplies and medicine."