Visible light in the Universe

Visible light

Light is energy that can take on many forms. Such as radio waves, microwaves, infrared, visible light, ultraviolet, X-ray and gamma radiation are all different forms of light.

Radio Waves

What are radio waves? Naturally occurring radio waves are made by lightning, or by astronomical objects. Radio frequencies have been used in the medical field, for example, to help treat sleep apnea.


What are microwaves? Microwaves are good for transmitting information from one place to another because its energy can penetrate haze, light rain and snow, clouds, and smoke.

Active microwave experiments have also been done with objects in the solar system, such as determining the distance to the Moon or mapping the invisible surface of Venus through cloud cover.


What is Infrared light? We experience far-infrared radiation every day in the form of heat that we feel from sunlight, a fire, or a warm sidewalk. Infrared can also be used to detect protostars before they begin to emit visible light.

Visible Light

Visible light (often referred to simply as light.) is electromagnetic radiation that is visible to the human eye and is responsible for the sense of sight. The Sun is Earth’s primary source of light. Therefore, about 44% of the Sun’s electromagnetic radiation that reaches the ground is the visible light range.


Though ultraviolet wavelengths are invisible to the human eye, some insects, like bumblebees, can see them. Through some ultraviolet waves, the Sun penetrate Earth’s atmosphere (and give us sunburns). Most of them are blocked by various gases like ozone.


Earth’s atmosphere is thick enough that virtually no X-rays are able to penetrate from outer space all the way to the Earth’s surface.

The photons collected in space by X-ray telescopes reveal the hot spots in the Universe. Regions where particles have been energized or raised to high temperatures by gigantic explosions or intense gravitational fields.

Gamma Ray

Rare terrestrial natural sources produce gamma rays that are not of a nuclear origin, such as lightning strikes and terrestrial gamma-ray flashes. More typical production of gamma-ray beams emanates from pulsars within the Milky Way galaxy.