NASA

The imaging spectroradiometer on NASA's Aqua satellite acquired this image of the swollen Mississippi River on May 5, 2011.

NASA

This "before" image of the same region of the Mississippi River Valley was taken a year ago, on May 5, 2010.

Before-and-after satellite imagery reveals how much this month's flooding has changed the shape of the Mississippi River.

The upper image was captured by NASA's Aqua satellite, using its Moderate Resolution Imaging Spectroradiometer, or MODIS, on May 5, 2011. The lower image was taken exactly one year earlier with the same imaging instrument.

Both images use a combination of infrared and visible light to distinguish between different surface features. The water is shown in shades of blue. The clouds visible in this month's image are a pale blue-green. Vegetation is green, and soil is brown. Such images can be used to assess the floods' long-term effects on agriculture in the region.

More satellite views in the news:

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• How satellites helped get Osama bin Laden
• Satellite views from our holiday calendar
• Slideshow: Earth as art

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