NASA Earth Observatory: King Fire in California, False-Colour Infrared image

On Sept. 19, 2014, the Operational Land Imager (OLI) on the Landsat 8 satellite captured these images of the King fire in Eldorado National Forest. 

In the false-colour image, burned forest appears red; unaffected forests are green; cleared forest is beige; and smoke is blue. 

As of Sept. 23, the blaze had charred 36,320 hectares (89,571 acres).

Credit: NASA Earth Observatory

NASA MESSENGER: False-Colour Image of Earth Highlights Plant Growth

On Aug. 3, 2004, NASA’s Mercury Surface, Space Environment, Geochemistry, and Ranging (MESSENGER) spacecraft began a seven-year journey, spiraling through the inner solar system to Mercury. 

One year after launch, the spacecraft zipped around Earth, getting an orbit correction from Earth’s gravity and getting a chance to test its instruments by observing its home planet.

Credit: NASA /Johns Hopkins University Applied Physics Laboratory /Carnegie Institution of Washington

This image is a view of South America and portions of North America and Africa from the Mercury Dual Imaging System’s (MDIS) wide-angle camera aboard MESSENGER.

MDIS, records light at eleven different wavelengths, including visible and infrared light. Combining blue, red, and green light results in a true-colour image from the observations.

The image substitutes infrared light for blue light in the three-band combination.

The resulting image is crisper than the natural colour version because our atmosphere scatters blue light.

Infrared light, however, passes through the atmosphere with relatively little scattering and allows a clearer view. That wavelength substitution makes plants appear red. Why?

Plants reflect near-infrared light more strongly than either red or green, and in this band combination, near-infrared is assigned to look red.

Apart from getting a clearer image, the substitution reveals more information than natural colour.

Healthy plants reflect more near-infrared light than stressed plants, so bright red indicates dense, growing foliage.

For this reason, biologists and ecologists occasionally use infrared cameras to photograph forests.