A report on Light, Ultraviolet and Sun

A triangular prism dispersing a beam of white light. The longer wavelengths (red) and the shorter wavelengths (blue) are separated.

Levels of ozone at various altitudes (DU/km) and blocking of different bands of ultraviolet radiation: In essence, all UVC is blocked by diatomic oxygen (100–200 nm) or by ozone (triatomic oxygen) (200–280 nm) in the atmosphere. The ozone layer then blocks most UVB. Meanwhile, UVA is hardly affected by ozone, and most of it reaches the ground. UVA makes up almost all UV light that penetrates the Earth's atmosphere.

The electromagnetic spectrum, with the visible portion highlighted

A 380 nanometer UV LED makes some common household items fluoresce.

Illustration of the Sun's structure, in false color for contrast

Ultraviolet photons harm the DNA molecules of living organisms in different ways. In one common damage event, adjacent thymine bases bond with each other, instead of across the "ladder". This "thymine dimer" makes a bulge, and the distorted DNA molecule does not function properly.

Illustration of a proton-proton reaction chain, from hydrogen forming deuterium, helium-3, and regular helium-4.

Beam of sun light inside the cavity of Rocca ill'Abissu at Fondachelli-Fantina, Sicily

Sunburn effect (as measured by the UV index) is the product of the sunlight spectrum (radiation intensity) and the erythemal action spectrum (skin sensitivity) across the range of UV wavelengths. Sunburn production per milliwatt of radiation intensity is increased by nearly a factor of 100 between the near UV‑B wavelengths of 315–295 nm

Illustration of different stars's internal structure, the Sun in the middle has an inner radiating zone and an outer convective zone.

$Due to refraction, the straw dipped in water appears bent and the ruler scale compressed when viewed from a shallow angle.$

Demonstration of the effect of sunscreen. The man's face has sunscreen on his right side only. The left image is a regular photograph of his face; the right image is of reflected UV light. The side of the face with sunscreen is darker because the sunscreen absorbs the UV light.

High-resolution image of the Sun's surface taken by the Daniel K. Inouye Solar Telescope (DKIST)

Hong Kong illuminated by colourful artificial lighting.

Signs are often used to warn of the hazard of strong UV sources.

During a total solar eclipse, the solar corona can be seen with the naked eye, during the brief period of totality.

UV damaged polypropylene rope (left) and new rope (right)

The Sun's transition region taken by Hinode's Solar Optical Telescope

IR spectrum showing carbonyl absorption due to UV degradation of polyethylene

Sunlight and glare seen overlooking from the International Space Station

$Thomas Young's sketch of a double-slit experiment showing diffraction. Young's experiments supported the theory that light consists of waves.$

A portrait taken using only UV light between the wavelengths of 335 and 365 nanometers.

Once outside the Sun's surface, neutrinos and photons travel at the speed of light

Aurora at Jupiter's north pole as seen in ultraviolet light by the Hubble Space Telescope.

A bird appears on many Visa credit cards when they are held under a UV light source

Measurements from 2005 of solar cycle variation during the previous 30 years

After a training exercise involving fake body fluids, a healthcare worker's personal protective equipment is checked with ultraviolet light to find invisible drops of fluids. These fluids could contain deadly viruses or other contamination.

A collection of mineral samples brilliantly fluorescing at various wavelengths as seen while being irradiated by UV light.

The size of the current Sun (now in the main sequence) compared to its estimated size during its red-giant phase in the future

Effects of UV on finished surfaces in 0, 20 and 43 hours.

The Solar System, with sizes of the Sun and planets to scale. The terrestrial planets are on the right, the gas and ice giants are on the left.

A low-pressure mercury vapor discharge tube floods the inside of a hood with shortwave UV light when not in use, sterilizing microbiological contaminants from irradiated surfaces.

The Trundholm sun chariot pulled by a horse is a sculpture believed to be illustrating an important part of Nordic Bronze Age mythology.

Entomologist using a UV light for collecting beetles in Chaco, Paraguay.

Sol, the Sun, from a 1550 edition of Guido Bonatti's Liber astronomiae.

False-color image taken in 2010 as seen in 30.4-nanometer ultraviolet light wavelength

A false-color of a coronal hole on the Sun forming a question mark (22 December 2017)

A false-color solar prominence erupts in August 2012, as captured by the Solar Dynamics Observatory

The Sun seen from Earth, with glare from the lenses. The eye also see glare when looked towards the Sun directly.

Sun and Immortal Birds Gold Ornament by ancient Shu people. The center is a sun pattern with twelve points around which four birds fly in the same counterclockwise direction, Shang dynasty

Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nm (with a corresponding frequency around 30 PHz) to 400 nm (750 THz), shorter than that of visible light, but longer than X-rays.

- Ultraviolet

Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

- Light

It is a nearly perfect ball of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy mainly as light, ultraviolet, and infrared radiation.

- Sun

The main source of natural light on Earth is the Sun.

- Light

The Sun emits ultraviolet radiation at all wavelengths, including the extreme ultraviolet where it crosses into X-rays at 10 nm.

- Ultraviolet

4 related topics with Alpha

Infrared

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This false-color infrared space telescope image has blue, green and red corresponding to 3.4, 4.6, and 12 μm wavelengths, respectively.

Plot of atmospheric transmittance in part of the infrared region

Materials with higher emissivity appear closer to their true temperature than materials that reflect more of their different-temperature surroundings. In this thermal image, the more reflective ceramic cylinder, reflecting the cooler surroundings, appears to be colder than its cubic container (made of more emissive silicon carbide), while in fact, they have the same temperature.

Active-infrared night vision: the camera illuminates the scene at infrared wavelengths invisible to the human eye. Despite a dark back-lit scene, active-infrared night vision delivers identifying details, as seen on the display monitor.

Hyperspectral thermal infrared emission measurement, an outdoor scan in winter conditions, ambient temperature −15 °C, image produced with a Specim LWIR hyperspectral imager. Relative radiance spectra from various targets in the image are shown with arrows. The infrared spectra of the different objects such as the watch clasp have clearly distinctive characteristics. The contrast level indicates the temperature of the object.

Infrared light from the LED of a remote control as recorded by a digital camera

Reflected light photograph in various infrared spectra to illustrate the appearance as the wavelength of light changes.

Infrared hair dryer for hair salons, c. 2010s

IR satellite picture of cumulonimbus clouds over the Great Plains of the United States.

The greenhouse effect with molecules of methane, water, and carbon dioxide re-radiating solar heat

Beta Pictoris with its planet Beta Pictoris b, the light-blue dot off-center, as seen in infrared. It combines two images, the inner disc is at 3.6 μm.

An infrared reflectogram of Mona Lisa by Leonardo da Vinci

Thermographic image of a snake eating a mouse

Infrared radiation was discovered in 1800 by William Herschel.

Infrared (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light.

Slightly more than half of the energy from the Sun was eventually found, through Herschel's studies, to arrive on Earth in the form of infrared.

Of this energy, 527 watts is infrared radiation, 445 watts is visible light, and 32 watts is ultraviolet radiation.

Sunlight

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Sunrise over the Gulf of Mexico and Florida. Taken on 20 October 1968 from Apollo 7.

Sunlight on Mars is dimmer than on Earth. This photo of a Martian sunset was imaged by Mars Pathfinder.

Solar irradiance spectrum at top of atmosphere, on a linear scale and plotted against wavenumber

Sunlight shining through clouds, giving rise to crepuscular rays

Spectrum of the visible wavelengths at approximately sea level; illumination by direct sunlight compared with direct sunlight scattered by cloud cover and with indirect sunlight by varying degrees of cloud cover. The yellow line shows the power spectrum of direct sunlight under optimal conditions. To aid comparison, the other illumination conditions are scaled by the factor shown in the key so they match at about 470 nm (blue light).

Sunlight penetrating through a forest canopy in Germany

Édouard Manet: Le déjeuner sur l'herbe (1862-63)

Téli verőfény ("Winter Sunshine") by László Mednyánszky, early 20th century

Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light.

When direct solar radiation is not blocked by clouds, it is experienced as sunshine, a combination of bright light and radiant heat.

Electromagnetic spectrum

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Range of frequencies of electromagnetic radiation and their respective wavelengths and photon energies.

A diagram of the electromagnetic spectrum, showing various properties across the range of frequencies and wavelengths

Plot of Earth's atmospheric opacity to various wavelengths of electromagnetic radiation. This is the surface-to-space opacity, the atmosphere is transparent to longwave radio transmissions within the troposphere but opaque to space due to the ionosphere.

Plot of atmospheric opacity for terrestrial to terrestrial transmission showing the molecules responsible for some of the resonances

The amount of penetration of UV relative to altitude in Earth's ozone

This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.

The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light.

Radiation

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Often categorized as either ionizing or non-ionizing depending on the energy of the radiated particles.

The international symbol for types and levels of ionizing radiation (radioactivity) that are unsafe for unshielded humans. Radiation, in general, exists throughout nature, such as in light and sound.

Some kinds of ionizing radiation can be detected in a cloud chamber.

Graphic showing relationships between radioactivity and detected ionizing radiation

Gamma radiation detected in an isopropanol cloud chamber.

Alpha particle detected in an isopropanol cloud chamber

Electrons (beta radiation) detected in an isopropanol cloud chamber

In electromagnetic radiation (such as microwaves from an antenna, shown here) the term "radiation" applies only to the parts of the electromagnetic field that radiate into infinite space and decrease in intensity by an inverse-square law of power so that the total radiation energy that crosses through an imaginary spherical surface is the same, no matter how far away from the antenna the spherical surface is drawn. Electromagnetic radiation includes the far field part of the electromagnetic field around a transmitter. A part of the "near-field" close to the transmitter, is part of the changing electromagnetic field, but does not count as electromagnetic radiation.

electromagnetic radiation, such as radio waves, microwaves, infrared, visible light, ultraviolet, x-rays, and gamma radiation (γ)

Herschel, like Ritter, used a prism to refract light from the Sun and detected the infrared (beyond the red part of the spectrum), through an increase in the temperature recorded by a thermometer.