Visualization: From Energy to Image


False color, or representative color, is used to help scientists visualize data from wavelengths beyond the visible spectrum. Scientific instruments onboard NASA spacecraft sense regions within the electromagnetic spectrum—spectral bands. The instruments direct the electromagnetic energy onto a detector, where individual photons yield electrons related to the amount of incoming energy. The energy is now in the form of "data," which can be transmitted to Earth and processed into images.


Digital cameras operate similarly to some scientific instruments. A sensor in the camera captures the brightness of red, green, and blue light and records these brightness values as numbers. The three sets of data are then combined in the red, green, and blue channels of a computer monitor to create a color image.

Three small grayscale images showing each channel of a digital photo of a hot air balloon. The blue channel shows a light gray area along the blue strip of the balloon. The composite shows a full color image with bright yellow, blue, orange and red stripes.
Digital image in color


Instruments onboard satellites can also capture visible light data to create natural color, or true color, satellite images. Data from visible light bands are composited in their respective red, green, and blue channels on screen. The image simulates a color image that our eyes would see from the vantage point of the spacecraft.

Three small grayscale images showing each channel of an image of Saturn. The forth image shows a full color image of Saturn with light browns and warm grays.
Saturn shown in natural color. Credit: NASA and The Hubble Heritage Team


Sensors can also record brightness values in regions beyond visible light. This Hubble image of Saturn was taken at longer infrared wavelengths and composited in the red, green, and blue channels respectively. The resulting false-color composite image reveals compositional variations and patterns that would otherwise be invisible.

Three small grayscale images showing each channel of an image of Saturn in false color. The forth image show Saturn with brilliant colors of purple, blue, green and orange.
Saturn shown in false color. Credit: NASA/JPL/STScI
false-color infrared image from the Thermal Emission Imaging System (THEMIS) camera onboard the Mars Odyssey spacecraft
Martian Soil - This false-color infrared image from the Thermal Emission Imaging System (THEMIS) camera onboard the Mars Odyssey spacecraft reveals the differences in the mineralogy, chemical composition, and structure of the Martian surface. Bands 5 (9.35 µm, 1070 cm-1), 7 (11.04 µm, 906 cm-1), and 9 (12.57 µm, 796 cm-1) are displayed in blue, green, and red, respectively. Large deposits of the mineral olivine appear in this image as magenta to purple-blue. Credit: Mars Odyssey Thermal Emission Imaging System, NASA/JPL/ASU. Expand Image


This composite image of the spiral galaxy Messier 101 combines views from Spitzer, Hubble, and Chandra space telescopes. The red color shows Spitzer's view in infrared light. It highlights the heat emitted by dust lanes in the galaxy where stars can form. The yellow color is Hubble's view in visible light. Most of this light comes from stars, and they trace the same spiral structure as the dust lanes. The blue color shows Chandra's view in x-ray light. Sources of x-rays include million-degree gas, exploded stars, and material colliding around black holes.

The three small images used for the composite show a galaxy in red, yellow, and blue. The composite shows all three colors together revealing a multi-colored galaxy.
Messier 101 galaxy in x-ray, infrared, and visible light. Credit: NASA, ESA, CXC, JPL, Caltech and STScI

Such composite images allow astronomers to compare how features are seen in multiple wavelengths. It's like "seeing" with a camera, night-vision goggles, and x-ray vision all at once.


To help scientists visualize a data set of just one range of values, such as temperature or rainfall, the values are often mapped to a color scale from minimum to maximum. The “color map” below visualizes sea surface salinity data from the Aquarius satellite using a scale from blue to white. The blue end of the scale shows the lowest amounts of dissolved salts in the ocean and the white end shows the highest amounts.

An image of the Earth with the ocean colored a variety of shades from white to dark blue. The white indicates high levels of salinity and are prevalent in the Atlantic Ocean, Mediterranean Sea and bodies of water around the Middle East.
Map of Sea Surface Salinity. Credit: NASA/Goddard Space Flight Center

A commonly used color scale has red at one end and blue at the other creating a “rainbow-like” scale. The sea surface temperature map below uses a scale from dark blue for cold temperatures to red for warm temperatures..

An image of the Earth with red color around the equator representing ocean temperatures of 30 degrees centigrade. The colors get cooler, from yellow to green to blue, the closer the ocean is to the poles.
Map of Sea Surface Temperatures. Credit: NASA/Goddard Space Flight Center

In some cases these colors do not represent traditional meaning—such as red referring to “bad” or “hot.” For example, red in the map below is good because it indicates high amounts of chlorophyll associated with an abundance of microscopic plants known as phytoplankton that support the ocean ecosystem.

Image using color to represent different levels of chlorophyll in the oceans and on land
Map of Chlorophyll Concentrations. Credit: NASA/Goddard Space Flight Center

Learn more with this activity about Color Mapping.


National Aeronautics and Space Administration, Science Mission Directorate. (2010). Visualizations: From Energy to Image. Retrieved [insert date - e.g. August 10, 2016], from NASA Science website:


Science Mission Directorate. "Visualizations: From Energy to Image" NASA Science. 2010. National Aeronautics and Space Administration. [insert date - e.g. 10 Aug. 2016]

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