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electromagnetic spectrum
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Diagram of the electromagnetic spectrum showing frequency, wavelength, and photon energy scales, with labeled regions for gamma rays, X-rays, ultraviolet, infrared, radar, microwaves, television, and radio waves. The visible light portion is highlighted and enlarged to the right, displaying its color range from violet to red. Diagram of the electromagnetic spectrum with labeled sections for radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each paired with an example use and corresponding image. electromagnetic spectrum Figure 1: The electromagnetic spectrum. Diagram of the electromagnetic spectrum showing different types of waves arranged by wavelength and frequency, from gamma rays and X-rays to ultraviolet, visible light, infrared, microwave, TV/FM radio, shortwave radio, AM radio, and longwave radio.
Understand how the electromagnetic spectrum helps study the celestial bodies
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Diagram of the electromagnetic spectrum showing frequency, wavelength, and photon energy scales, with labeled regions for gamma rays, X-rays, ultraviolet, infrared, radar, microwaves, television, and radio waves. The visible light portion is highlighted and enlarged to the right, displaying its color range from violet to red.
The electromagnetic spectrum. The narrow range of visible light is shown enlarged at the right.

electromagnetic spectrum

physics
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The fastest arms race is happening in the electromagnetic spectrum • Oct. 24, 2026, 9:49 PM ET (Jerusalem Post)

electromagnetic spectrum, the entire distribution of electromagnetic radiation according to frequency or wavelength. Although all electromagnetic waves travel at the speed of light in a vacuum, they do so at a wide range of frequencies, wavelengths, and photon energies. The electromagnetic spectrum comprises the span of all electromagnetic radiation and consists of many subranges, commonly referred to as portions, such as visible light or ultraviolet radiation. The various portions bear different names based on differences in behaviour in the emission, transmission, and absorption of the corresponding waves and also based on their different practical applications. There are no precise accepted boundaries between any of these contiguous portions, so the ranges tend to overlap.

Diagram of the electromagnetic spectrum with labeled sections for radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays, each paired with an example use and corresponding image.
Electromagnetic radiationRadio waves, infrared rays, visible light, ultraviolet rays, X-rays, and gamma rays are all types of electromagnetic radiation. Radio waves have the longest wavelength, and gamma rays have the shortest wavelength.

The entire electromagnetic spectrum, from the lowest to the highest frequency (longest to shortest wavelength), includes all radio waves (e.g., commercial radio and television, microwaves, radar), infrared radiation, visible light, ultraviolet radiation, X-rays, and gamma rays. Nearly all frequencies and wavelengths of electromagnetic radiation can be used for spectroscopy.

This article was most recently revised and updated by Melissa Petruzzello.