A report on Light and Sunlight

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

The Sun, as seen from low Earth orbit overlooking the International Space Station. This sunlight is not filtered by the lower atmosphere, which blocks much of the solar spectrum.

The electromagnetic spectrum, with the visible portion highlighted

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

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

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

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

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

Hong Kong illuminated by colourful artificial lighting.

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

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

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

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

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

- Sunlight

Sunlight provides the energy that green plants use to create sugars mostly in the form of starches, which release energy into the living things that digest them.

- Light

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.

Sunlight, at an effective temperature of 5,780 kelvins (5,510 °C, 9,940 °F), is composed of near-thermal-spectrum radiation that is slightly more than half infrared.

Sun

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Star at the center of the Solar System.

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

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

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

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

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

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

Sunlight and glare seen overlooking from the International Space Station

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

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

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

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.

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

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

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.

The energy of this sunlight supports almost all life on Earth by photosynthesis, and drives Earth's climate and weather.

Visible spectrum

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Portion of the electromagnetic spectrum that is visible to the human eye.

Newton's color circle, from Opticks of 1704, showing the colors he associated with musical notes. The spectral colors from red to violet are divided by the notes of the musical scale, starting at D. The circle completes a full octave, from D to D. Newton's circle places red, at one end of the spectrum, next to violet, at the other. This reflects the fact that non-spectral purple colors are observed when red and violet light are mixed.

Newton's observation of prismatic colors (David Brewster 1855)

How visible light interacts with objects to make them colorful

Approximation of spectral colors on a display results in somewhat distorted chromaticity

Earth's atmosphere partially or totally blocks some wavelengths of electromagnetic radiation, but in visible light it is mostly transparent

Electromagnetic radiation in this range of wavelengths is called visible light or simply light.

Newton observed that, when a narrow beam of sunlight strikes the face of a glass prism at an angle, some is reflected and some of the beam passes into and through the glass, emerging as different-colored bands.

Ultraviolet

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

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.

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

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.

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

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

IR spectrum showing carbonyl absorption due to UV degradation of polyethylene

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

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

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.

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

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.

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

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.

UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun.