When we smell something, what our body is really doing is sensing tiny amounts of different chemicals in the air. Different chemicals smell different to us. 

The Spitzer Space Telescope can “smell” different things using light! But it sees a far different slice of light from what we see. A rainbow, which separates the Sun’s white light into its different colors, shows us all the colors our eyes can see. But there are many other colors — or wavelengths — of light we don’t see. The Spitzer Space Telescope sees what is called infrared light. Infrared means “beyond red.”

Spitzer has three instruments that detect infrared light. Two of them make images of what they see. The third, called the Infrared Spectrograph, is the “sniffer.” This instrument separates the light into its colors the way the water droplets in the air make a rainbow.

Then, the spectrograph is so sensitive, it can detect whether some of the colors from an infrared “rainbow” are dimmer or brighter than others. It records what it sees. Just as different chemicals smell different to us, different chemicals look different to a spectrograph.  From that “fingerprint” of its light, scientists can tell what chemicals they’re looking at. Spitzer has “sniffed” stars, galaxies, enormous dust clouds and even planets that are too small to take pictures of, even with the biggest telescope in the world! 

You can see many of the beautiful images from Spitzer’s other two instruments when you play “Slyder” at spaceplace.nasa.gov/en/kids/spitzer/slyder.

This article was written by Diane K. Fisher and provided by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration.