Shop Windows to the Universe

The Winter 2010 issue of The Earth Scientist includes a variety of educational resources, ranging from astronomy to glaciers. Check out the other publications and classroom materials in our online store.
This is a thermogram of a house, an IR view of a house. It shows variations in the amount of heat that escapes from a home. Greater heat loss appears in red. Blue indicates areas where little or no heat radiates from the building.
Click on image for full size
Daedalus Enterprises, Inc., Ann Arbor, MI

Infrared (IR) Radiation

Infrared (IR) radiation is a type of electromagnetic radiation. Infrared "light" has a longer wavelength than visible light. Red light has a longer wavelength than other colors of light, and infrared has even longer waves than red does; so infrared is sort of "redder-than-red" light or "beyond red" light. We cannot see infrared radiation, but we can sometimes feel it as heat.

Infrared radiation lies between visible light and radio waves on the electromagnetic spectrum. IR light has wavelengths between about 1 millimeter and 750 nanometers. The wavelength of red light is 700 nanometers (or 7,000 ┼). Infrared radiation oscillates at rates between 300 gigahertz (GHz or 109 hertz) and 400 terahertz (THz or 1012 hertz).

The infrared spectrum is sometimes subdivided into the far infrared (1 mm to 10 Ám wavelengths), mid infrared (10 to 2.5 Ám wavelengths), and near infrared (2,500 to 750 nm wavelengths). A portion of the far IR, including wavelengths between 100 and 1,000 Ám, is sometimes referred to as the extreme infrared. Boundaries aren't always distinct, and difference between extreme IR radiation and microwave radio frequencies is less than crystal clear.

We feel infrared radiation as heat. The heat our hand feels when placed above a burner on an electric stovetop after the burner has been turned off (and is no longer glowing red) but has not yet cooled is infrared radiation.

Earth's atmosphere is opaque to much of the infrared part of the spectrum. Water vapor, carbon dioxide, methane, and other greenhouse gases tend to absorb IR radiation, trapping extra heat in Earth's lower atmosphere.

Night vision goggles and TV remote controls both make use of infrared "light" to accomplish their tasks.

Last modified July 13, 2005 by Randy Russell.

Shop Windows to the Universe Science Store!

Learn about Earth and space science, and have fun while doing it! The games section of our online store includes a climate change card game and the Traveling Nitrogen game!

Windows to the Universe Community



You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Electromagnetic Radiation

Electromagnetic radiation is the result of oscillating electric and magnetic fields. The wave of energy generated by such vibrations moves through space at the speed of light. And well it should... for...more

Radio Waves

Radio waves are a type of electromagnetic radiation. A radio wave has a much longer wavelength than does visible light. We use radio waves extensively for communications. Radio waves have wavelengths as...more

Earth's Greenhouse Gases

Even though only a tiny amount of the gases in Earthĺs atmosphere are greenhouse gases, they have a huge effect on climate. There are several different types of greenhouse gases. The major ones are carbon...more

Earth's Radiation Budget

Light from the Sun shines on Earth. Some of that light reflects off clouds back into space. Some of the light makes it to the ground and warms our planet. The warm ground and oceans give off infrared (IR)...more

Impact on Jupiter - July 2009

Anthony Wesley is an amateur astronomer in Australia. On the night of July 19, 2009, Wesley noticed a dark spot on Jupiter that hadn't been there before. He had discovered the remains of a huge impact...more

Hubble Space Telescope

The Hubble Space Telescope (HST) was one of the most important exploration tools of the past two decades, and will continue to serve as a great resource well into the new millennium. The HST found numerous...more


Light is very strange. Sometimes it is best to think of light as a series of waves. At other times, it is useful to think of light as a swarm of particles. When we think of light as particles, we call...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA