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From: Dan Richter (1:317/3)
To: All
Date: Thu, 11.03.21 12:00
MODIS Pic of the Day 11 March 2021
March 11, 2021 - Silver Rivers in the Democratic Republic of the Congo



Several rivers wind through the dense forests of the eastern Democratic
Republic of the Congo. Most of these rivers wind towards the Lualaba
River. In turn, the Lualaba flows into the Congo River—the second
longest river in Africa. On March 11, 2021, when the Moderate
Resolution Imaging Spectroradiometer (MODIS) on board NASA’s Terra
satellite acquired a true-color image of the region, parts of several
rivers glowed like liquid silver, dramatically contrasting against the
deep green of the forest.

The glowing silver is created by an optical phenomenon called
“sunglint”. When sun reflects off a smooth surface—an ocean, lake, or
river—at the same angle that a satellite sensor views it, the result is
a mirror-like shine. An image captured at this moment will show a
silver glow wherever the reflectance angle is exactly right. The “sweet
spot” for sunglint is relatively narrow in the east-to-west direction
but as the satellite is moving, it is longer along the track of the
satellite. The sunglint is quite bright in the center and quickly
becomes duller and disappears moving away from that central bright
spot. Yet rivers several hundred miles away from each other are each
affected by sunglint. The Lualaba River, running roughly south to north
is seen in the western (left) section of the image. It is not in
sunglint so appears dark.

Image Facts
Satellite: Terra
Date Acquired: 3/10/2021
Resolutions: 1km (133.3 KB), 500m (351.3 KB), 250m (197.1
Bands Used: 1,4,3
Image Credit: MODIS Land Rapid Response Team, NASA GSFC

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