Light sources

The Sun is the star located at the centre of the Solar System. It is a massive sphere of hot plasma, heated to incandescence by nuclear fusion reactions in its core, radiating the energy from its surface mainly as visible light and infrared radiation with 10% at ultraviolet energies. It is the main source of energy for life on Earth. The Sun has been an object of veneration in many cultures and a central subject of astronomical research since antiquity.

A star is a luminous spheroid of plasma held together by self-gravity. The nearest star to Earth is the Sun. Many other stars are visible to the naked eye at night; their immense distances from Earth make them appear as fixed points of light. The most prominent stars have been categorised into constellations and asterisms, and many of the brightest stars have proper names. Astronomers have assembled star catalogues that identify the known stars and provide standardized stellar designations. The observable universe contains an estimated to stars. Only about 4,000 of these stars are visible to t

An aurora ( aurorae or auroras) is a natural light display in Earth’s upper atmosphere caused by charged particles from the Sun colliding with atoms in the atmosphere. These collisions excite oxygen and nitrogen, which then emit light of different colors such as green, red, and purple. When observed in high-latitude regions they are called polar lights and aurora polaris. In the Arctic they are called northern lights (aurora borealis); in the Antarctic, the terms southern lights (aurora australis) are used. Auroras display dynamic patterns of radiant light that appear as curtains, rays, spiral

thumb|Ritual devils and townspeople participate in a Correfoc (firerun) at the culmination of Festa Major 2012, in Vilanova i la Geltrú Fireworks are low explosive pyrotechnic devices used for aesthetic and entertainment purposes. They are most commonly used in fireworks displays (also called a fireworks show or pyrotechnics), combining a large number of devices in an outdoor setting. Such displays are the focal point of many cultural and religious celebrations, though mismanagement can lead to fireworks accidents.

plasma "atmosphere" of the Sun

thumb|right|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.

thumb|Flying and glowing firefly, [[Photinus pyralis]] thumb|upright |Female glowworm, [[Lampyris noctiluca]] Bioluminescence is the production of light by an organism as the result of a chemiluminescence reaction. It occurs in a wide variety of organisms, including marine vertebrates and invertebrates, terrestrial arthropods such as fireflies, some fungi, and microorganisms such as some bacteria and dinoflagellates. In some animals, the light is bacteriogenic, produced by symbiotic bacteria such as those from the genus Vibrio; in others, it is autogenic, produced by the animals themselves. Bi

anthropogenic light in the night environment, caused by excess or misdirected lighting

thumb|alt=A miasma of plasma|Sun's surface in false color|228x228px The photosphere is a star's outer shell from which light is radiated. It extends into a star's surface until the plasma becomes opaque, equivalent to an optical depth of approximately , or equivalently, a depth from which 50% of light will escape without being scattered.

weather phenomenon

electromagnetic phenomenon

right|thumb|Luminol reacting with haemoglobin is a familiar demonstration of [[chemiluminescence.]] thumb|UV-induced photoluminescence used in microbiological diagnostics.

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glow in the night sky appearing to extend from the Sun's direction and along the zodiac

thumb|Earthlight illuminates the dim side of the Moon, while direct sunlight illuminates the bright side.

device producing a burst of artificial light

thumbnail|Views of a liquid crystal display, both with electroluminescent backlight switched on (top) and switched off (bottom) Electroluminescence (EL) is an optical and electrical phenomenon, in which a material emits light in response to the passage of an electric current or to a strong electric field. This is distinct from black body light emission resulting from heat (incandescence), illumination by light (photoluminescence), chemical reactions (chemiluminescence), reactions in a liquid (electrochemiluminescence), sound (sonoluminescence), or other mechanical action (mechanoluminescence),

right|thumb|Single-bubble sonoluminescence – a single, cavitating bubble Sonoluminescence is luminescence induced by sound waves, such as in the emission of light from imploding bubbles in a liquid when excited by sound. Sonoluminescence is sometimes considered a kind of mechanoluminescence. However, mechanoluminescence is typically defined as pertaining to solids, while sonoluminescence usually pertains to liquids. The related terms acoustoluminescence and sonotriboluminescence have been used to describe sound-induced luminescence in solids (e.g., crystals suspended in slurries).

atmospheric optical phenomenon in the form of a vertical band of light which appears to extend above and/or below a light source

thumb|Airglow over Auvergne, France thumb|Yellow, green and red bands of airglow along Earth's limb as seen from space.

thumb|200px|right|A campfire made using twigs and pine cones. A campfire is a fire at a campsite that provides light, warmth, and heat for cooking. It can also serve as a beacon and an insect and predator deterrent. Established campgrounds often provide a stone or steel fire ring for safety. Campfires are a popular feature of camping. At summer camps, the word campfire often refers to an event (ceremony, get together, etc.) at which there is a fire. Some camps refer to the fire itself as a campfire.

thumb|right|220px|Saturn's moon Mimas is lit by Saturnshine on the right and sunshine at the top. thumb|right|220px|The Moon lit by [[earthshine, captured by the lunar-prospecting Clementine spacecraft in 1994. Clementine's color enhanced image reveals (from right to left) the Moon lit by earthshine, the Sun's corona rising over the Moon's dark limb, and the planets Saturn, Mars, and Mercury (the three dots at lower left).]]

thumb|right|Triboluminescence of nicotine -salicylate Triboluminescence is a phenomenon in which light is generated when a material is mechanically pulled apart, ripped, scratched, crushed, or rubbed (see tribology). The phenomenon is not fully understood but appears in most cases to be caused by the separation and reunification of static electric charges, see also triboelectric effect. The term comes from the Greek τρίβειν ("to rub"; see tribology) and the Latin lumen (light). Triboluminescence can be observed when breaking sugar crystals and peeling adhesive tapes.

self-contained, short-term light-source

Section of Sun's atmosphere

thumb|Color cathodoluminescence of a diamond in Scanning electron microscope|SEM, real colors

optical phenomenon

unit of measurement

thumb|right|The night side of the Moon, illuminated by earthshine, becomes visible next to the narrow crescent (11 percent, age of the Moon = 3.3 days) with ash-grey moonlight.

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short-lived electrical phenomena that occur at high altitudes over lightning storms (sprites, jets, etc.)

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thumbnail|Views of a liquid-crystal display, both with electroluminescent backlight switched on (top) and switched off (bottom)

thumb|A STEVE over Little Bow Resort, [[Alberta, in August 2015]] thumb|A STEVE over Crossfield, Alberta, in March 2018 (around 12:30 a.m.)

thumb|Starry sky crossed with the Milky Way and a [[meteor]]

thunderstorm with little or no precipitation

outermost layer of a star's atmosphere

light created by gunfire

hypothesised glow in Venus's light

source of light

thumb|right|Mexico City at night, showing skyglow thumb|A map from 1996 to 1997 showing the extent of skyglow over Europe

particle accelerator designed to produce intense x-ray beams

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light source that emits light as single particles or photons

thumb|200px|Burning luchina thumb|A knife for splintering luchinas

electronic sound-responsive lighting device

Mechanoluminescence is light emission resulting from any mechanical action on a solid. Fractoluminescence is caused by stress that results in the formation of fractures, that in turn yield light. Piezoluminescence is caused by pressure that results in elastic deformation and large polarization from the piezoelectric effect. Triboluminescence is nominally caused by rubbing, but sometimes occurs because of resulting fractoluminescence. It is often used as a synonym.

Crystalloluminescence is the effect of luminescence produced during crystallization, specifically during nucleation. The phenomenon was first reported in the 1800s from the rapid crystallization of potassium sulfate from an aqueous solution.

falling of meteors