Scientists use different kinds of light to study the planets and stars. Scientists have long puzzled over whether light travels like waves across an ocean or like little grains (particles) that zip along really fast (i.e., at the ``speed of light''). Light behaves like both!
Different kinds of light are described by their wavelength. The different kinds of light are all forms of electromagnetic engergy. The different wavelengths make the Electromagnetic Spectrum.
Part of the electromagnetic spectrum is what we call visible light. You can see the visible light portion of the electromagnetic spectrum with your eyes. A rainbow shows all of the colors in this part of the spectrum.
X-rays are used by doctors to see your bones, radio waves bring music into your car, and microwaves can cook your food. These are all part of the electromagnetic spectrum.
The Mars Global Surveyor Thermal Emission Spectrometer (TES) can detect the part of the electromagnetic spectrum known as the thermal infrared. Your body detects thermal infrared energy by feeling it as heat. TES can actually separate thermal infrared energy in a way that makes a spectrum with wavelengths from 6 to 50 micrometers (nearly 1000 times smaller than 1 millimeter).
Click HERE to see more about the TES and what a thermal infrared spectrum looks like.