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Ultraviolet radiation, also known as simply UV, is electromagnetic radiation of wavelengths of 10–400 nanometers, shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun.
In reflected UV photography the subject is illuminated directly by UV emitting lamps (radiation sources) or by strong sunlight. A UV transmitting filter is placed on the lens, which allows ultraviolet radiation to pass and which absorbs or blocks all light and infrared radiation. UV filters are made from special colored glass and may be coated ...
UV observations can also provide essential information about the evolution of galaxies. They can be used to discern the presence of a hot white dwarf or main sequence companion in orbit around a cooler star. [3] [4] The ultraviolet universe looks quite different from the familiar stars and galaxies seen in visible light.
Extreme ultraviolet composite image of the Sun (red: 21.1 nm, green: 19.3 nm, blue: 17.1 nm) taken by the Solar Dynamics Observatory on August 1, 2010 13.5 nm extreme ultraviolet light is used commercially for photolithography as part of the semiconductor fabrication process.
The UV dose is measured in light energy per area, i.e. radiant exposure or fluence. The fluence a microbe is exposed to is the product of the light intensity, i.e. irradiance and the time of exposure, according to: UV dose (μJ/cm 2) = UV intensity (μW/cm 2) × exposure time (seconds) [76]
The Far UV Camera/Spectrograph can be seen in the background, under the shadow of the lunar module. The experiment was placed on the Descartes Highlands region of lunar surface where Apollo 16 astronauts John Young and Charles Duke landed in April 1972. To keep it cool and eliminate solar glare, it was placed in the shadow of the lunar module ...
International Ultraviolet Explorer (IUE or Explorer 57, formerly SAS-D) [2] was the first space observatory primarily designed to take ultraviolet (UV) electromagnetic spectrum. The satellite was a collaborative project between NASA , the United Kingdom 's Science and Engineering Research Council (SERC, formerly UKSRC) and the European Space ...
The pollen grains reflect UV-beta to shield their chromosomes stored in the pollen from UV-alpha which is important for making sure of reproductive success. [10] The technique of UV coloration has evolved in other species as well for various reasons. Similarly, carnivorous plants reflect and absorb UV to attract prey to it. [10]