Hertzsprung–Russell Diagram

Spectral Type

Brown dwarfs

White dwarfs

Red dwarfs

Subdwarfs

Main sequence
("dwarfs")

Subgiants

Giants

Bright Giants

Supergiants

Hypergiants

absolute

magni-

tude

(M_V)

A red giant is a luminous giant star of low or intermediate mass (roughly 0.5–10 solar masses) in a late phase of stellar evolution. The outer atmosphere is inflated and tenuous, making the radius immense and the surface temperature low, somewhere from 5,000 K and lower. The appearance of the red giant is from yellow orange to red, including the spectral types K and M, but also class S stars and most carbon stars.

The most common red giants are the so-called red giant branch stars (RGB stars) whose shells are still fusing hydrogen into helium, while the core is inactive helium. Another case of red giants are the asymptotic giant branch stars (AGB) that produce carbon from helium by the triple-alpha process.^[1] To the AGB stars belong the carbon stars of type C-N and late C-R.

Prominent bright red giants in the night sky include Aldebaran (Alpha Tauri), Arcturus (Alpha Bootis), and Gamma Crucis (Gacrux), while the even larger Antares (Alpha Scorpii) and Betelgeuse (Alpha Orionis) are red supergiants.

Characteristics[link]

The red giant Mira

Red giants are stars that have exhausted the supply of hydrogen in their cores and switched to thermonuclear fusion of hydrogen in a shell surrounding the core. They have radii tens to hundreds of times larger than that of the Sun. However, their outer envelope is lower in temperature, giving them an orange hue. Despite the lower energy density of their envelope, red giants are many times more luminous than the Sun because of their large size. Main sequence stars of spectral types A through K are believed to evolve into red giants.^[2]

The stellar limb of a red giant is not sharply-defined, as depicted in many illustrations. Instead, due to the very low mass density of the envelope, such stars lack a well-defined photosphere. The body of the star gradually transitions into a 'corona' with increasing radii.^[3][4]

Stellar evolution[link]

Red giants are evolved from main sequence stars with masses in the range from about 0.5 solar masses to somewhere between 4 and 6 solar masses.^[5] When a star initially forms from a collapsing molecular cloud in the interstellar medium, it contains primarily hydrogen and helium, with trace amounts of "metals" (elements with atomic number > 2, i. e. every element except hydrogen and helium). These elements are all uniformly mixed throughout the star. The star reaches the main sequence when the core reaches a temperature high enough to begin fusing hydrogen (a few million Kelvin) and establish hydrostatic equilibrium. Over its main sequence life, the star slowly converts the hydrogen in the core into helium; its main sequence life ends when nearly all the hydrogen in the core has been used. For the Sun, the main sequence lifetime is approximately 10 billion years; the lifetime is shorter for more massive stars and longer for less massive stars.^[1]

When the star exhausts the hydrogen fuel in its core, nuclear reactions in the core stop, so the core begins to contract due to its gravity. This heats a shell just outside the core, where hydrogen remains, initiating fusion of hydrogen to helium in the shell. The higher temperatures lead to increasing reaction rates, producing enough energy to increase the star's luminosity by a factor of 1,000–10,000. The outer layers of the star then expand greatly, beginning the red giant phase of the star's life. Due to the expansion of the outer layers of the star, the energy produced in the core of the star is spread over a much larger surface area, resulting in a lower surface temperature and a shift in the star's visible light output towards the red – hence red giant, even though the color usually is orange. At this time, the star is said to be ascending the red giant branch of the Hertzsprung-Russell (H-R) diagram.^[1] The outer layers are convective, which causes material exposed to nuclear "burning" in the star's interior (but not its core) to be brought to the star's surface for the first time in the star's history, an event called the first dredge-up.

The mechanism that ends the complete collapse of the core and the ascent up the red giant branch depends on the mass of the star. For the Sun and red giants less than 2.571 solar masses,^{[citation needed]} the core will become dense enough that electron degeneracy pressure will prevent it from collapsing further. Once the core is degenerate, it will continue to heat until it reaches a temperature of roughly 10⁸ K, hot enough to begin fusing helium to carbon via the triple-alpha process. Once the degenerate core reaches this temperature, the entire core will begin helium fusion nearly simultaneously in a so-called helium flash. In more massive stars, the collapsing core will reach 10⁸ K before it is dense enough to be degenerate, so helium fusion will begin much more smoothly, with no helium flash. Once the star is fusing helium in its core, it contracts and is no longer considered a red giant.^[1] The core helium fusing phase of a star's life is called the horizontal branch in metal-poor stars, so named because these stars lie on a nearly horizontal line in the H-R diagram of many star clusters. Metal-rich helium-fusing stars instead lie on the so-called red clump in the H-R diagram.^[6]

In stars massive enough to ignite helium fusion, an analogous process occurs when central helium is exhausted and the star switches to fusing helium in a shell, although with the additional complication that in many cases hydrogen fusion will continue in a shell at lesser depth. This puts stars onto the asymptotic giant branch, a second red giant phase.^[7][8] More massive stars continue to repeat this cycle, fusing heavier elements in successive phases, each lasting more briefly than the previous.

A solar mass star will never fuse carbon. Instead, at the end of the asymptotic giant branch phase the star will eject its outer layers, forming a planetary nebula with the core of the star exposed, ultimately becoming a white dwarf. The ejection of the planetary nebula finally ends the red giant phase of the star's evolution.^[1]

The red giant phase typically lasts only a few million years^[9] and hence is very brief compared to the billions of years that stars of roughly solar mass will spend on the main sequence.

Stars that do not become red giants[link]

Red dwarf stars with less than 0.35 solar masses are full convective,^[10][11] which means they mix the helium produced at their cores throughout the rest of their bodies. As a result, these stars do not accumulate an inert core of helium, so they are predicted to exhaust all of their hydrogen fuel without ever becoming red giants.^[12] The expected lifespan of these stars is much greater than the current age of the universe, and hence there are no observations of these stars toward the end of their main sequence lifetime.

Very high mass stars develop into supergiant stars that follow an evolutionary track that takes them back and forth horizontally over the HR diagram, at the right end constituting red supergiants. These usually end their life as type II supernova.

[edit] The Sun as a red giant

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

An artist's depiction of the Sun entering its red giant phase viewed from Earth. All life on Earth is extinct at this phase.

The Sun is predicted to become a red giant in approximately 5 billion years.^[7] It is calculated that the Sun will become sufficiently large enough to engulf the current orbits of the solar system's inner planets, up to Earth,^[13][14][15] and its radius will expand to a minimum of 200 times its current value.^[16] The Sun will lose a significant fraction of its mass in the process of becoming a red giant, and there is a chance that Mars and all the outer planets will escape as their resulting orbits will widen.^[17] Mercury and most likely Venus will have been swallowed by Sun's outer layer at this time. Earth's fate is less clear. Earth could technically achieve a widening of its orbit and could potentially maintain a sufficiently high angular velocity to keep it from becoming engulfed. ^[18] In order to do so, its orbit needs to increase to between 1.3 AU (190,000,000 km) and 1.7 AU (250,000,000 km).^[19] However the results of studies announced in 2008 show that due to tidal interaction between Sun and Earth, Earth would actually fall back into a lower orbit, and get engulfed and incorporated inside the sun before the Sun reaches its largest size, despite the Sun losing about 38% of its mass.^[20] Before this happens, Earth's biosphere will have long been destroyed by the Sun's steady increase in brightness as its hydrogen supply dwindles and its core contracts, even before the transition to a red giant. After just over 1 billion years, the extra solar energy input will cause Earth's oceans to evaporate and the hydrogen from the water to be lost permanently to space, with total loss of water by 3 billion years.^[21] Earth's atmosphere and lithosphere will become like those of Venus. Over another billion years, most of the atmosphere will get lost in space as well,^[17] ultimately leaving Earth as a desiccated, dead planet with a surface of molten rock.

References[link]

v t e Star Evolution Formation Pre–main sequence Main sequence Horizontal branch Asymptotic giant branch Dredge-up Instability strip Red clump PG1159 star Mira variable Planetary nebula Protoplanetary nebula Luminous red nova Luminous blue variable Wolf–Rayet star Supernova impostor Supernova Hypernova Hertzsprung–Russell diagram Color–color diagram Protostars Molecular cloud H II region Bok globule Young stellar object Herbig–Haro object Hayashi track Hayashi limit Henyey track Orion T Tauri FU Orionis Herbig Ae/Be Luminosity class Subdwarf Dwarf Blue Red Subgiant Giant Blue Red Bright giant Supergiant Blue Red Yellow Hypergiant Yellow Blue straggler Spectral classification O B A F G K M Be OB Subdwarf B Late-type Peculiar Am Ap/Bp Oscillating Barium Carbon CH Extreme helium Lambda Boötis Lead Mercury-manganese S Shell Technetium Remnants White dwarf Black dwarf Helium planet Neutron star Pulsar Magnetar Stellar black hole Compact star Quark Exotic Stellar core: EF Eridani B Failed and theoretical stars Substellar object Brown dwarf Sub-brown dwarf Planetar Boson star Dark-matter star Quasi-star Thorne–Żytkow object Iron star Nucleosynthesis Alpha process Triple-alpha process Proton–proton chain Helium flash CNO cycle Lithium burning Carbon burning Neon burning Oxygen burning Silicon burning S-process R-process Fusor Nova Remnants Structure Core Convection zone Microturbulence Oscillations Radiation zone Atmosphere Photosphere Starspot Chromosphere Corona Stellar wind Bubble Asteroseismology Eddington luminosity Kelvin–Helmholtz mechanism Properties Designation Dynamics Effective temperature Kinematics Magnetic field Magnitude Absolute Mass Metallicity Rotation UBV color Variability Star systems Binary Contact Common envelope Multiple Accretion disc Planetary system Earth's Solar System Earth-centric observation of Pole star Circumpolar star Magnitude Apparent Extinction Photographic Color Radial velocity Proper motion Parallax Photometric-standard star Lists Star names Arabic Chinese Most massive Least massive Largest Brightest Historical Most luminous Nearest Nearest bright Stars with exoplanets Brown dwarfs Planetary nebulae Novae Notable supernovae Supernova remnants Supernova candidates Timeline of stellar astronomy Related articles Planet Star cluster Association Open cluster Globular cluster Galaxy Supercluster Helioseismology Guest star Constellation Asterism Gravity Intergalactic star Infrared dark cloud Star portal

Red
— Spectral coordinates —
Wavelength		~620–740[1][2] nm
Frequency		~480–400 THz
— Common connotations —
Aggression, anger, love, negativity, passion, socialism, communism, Valentine's Day, heat, fire, beauty, hunger, leadership, masculinity, injury, danger, blood, Christmas, volcanoes, conservatism (US), error, courage, stop, failure, drug intolerance, wrong way, death, Christianity, war
— Color coordinates —
Hex triplet		#FF0000
sRGBB	(r, g, b)	(255, 0, 0)
Source		X11
B: Normalized to [0–255] (byte)

Red is any of a number of similar colors evoked by light consisting predominantly of the longest wavelengths discernible by the human eye, in the wavelength range of roughly 630–740 nm.^[2] Longer wavelengths just past this range are called infrared (below red) and cannot be seen by the naked eye although they can be sensed as heat. In some cultures, certain shades of red are used to symbolize anger or aggression.

It is the color of blood when it is exposed to sunlight. In western countries, it is most commonly referred to as a color of evil, love, and sometimes, though rarely, happiness.

Etymology and definitions[link]

The word red comes from the Old English rēad.^[3] The word can be further traced to the Proto-Germanic rauthaz and the Proto-Indo European root reudh-. In Sanskrit, the word rudhira means red or blood. In the English language, the word red is associated with the color of blood, certain flowers (e.g., roses), and ripe fruits (e.g., apples, cherries). Fire is also strongly connected, as is the sun and the sky at sunset. Healthy, light-skinned people are sometimes said to have a "ruddy" complexion (as opposed to appearing pale). After the rise of socialism in the mid-19th century, red was used to symbolize and describe revolutionary movements.^[4]

In science[link]

Red blood cell agar

Colorimetry, color science, photography[link]

Red is any of a number of similar colors evoked by light, consisting predominantly of the longest wavelengths of light discernible by the human eye in the wavelength range of approximately 630–700 nm.^[2] Longer wavelengths just past this range are called infrared, or below red, and cannot be seen by human eyes, although they can be sensed as heat.^[5] Red's wavelength has been an important factor in laser technologies; red lasers, used in early compact disc technologies, are being replaced by blue lasers, as red's longer wavelength causes the laser's recordings to take up more space on the disc than would blue-laser recordings.^[6] A main theory for why primates developed sensitivity to red is that it allowed ripe fruit to be distinguished from unripe fruit and inedible vegetation.^[7] This further drove other adaptations taking advantage of this new ability, such as red faces.^[8] Red light is also used to preserve night vision in low-light or night time situations, as the rod cells in the human eye are not sensitive to red.^[9][10] Red is one of the three additive primary colors of light, complementary to cyan, in RGB color systems. Red is also one of the three subtractive primary colors of RYB color space, but not of CMYK color space.^[11]

One common use of red as an additive primary color is in the RGB color model. Because red is not by itself standardized, color mixtures based on red are not exact specifications of color either. The United States government sets certain specifications for what paints to use when red is stated in a design.^[12] In order for computers to produce exact colors, the color red needs to be defined in terms of an absolute color space, such as sRGB^[13] color correction (so that a standardized red is produced that is not in fact the full intensity of only the red colorant).

Red illumination was (and sometimes still is) used as a safelight while working in a darkroom as it does not expose most photographic paper and some films.^[14] Though many more modern darkrooms use an amber safelight, red illumination is closely associated with the darkroom in the public mind.

Lasers[link]

Lasers emitting in the red region of the spectrum have been available since the invention of the ruby laser in 1960. In 1962 the red helium-neon laser was invented,^[15] and these two types of lasers were widely used in many scientific applications including holography, and in education. Red helium-neon lasers were used commercially in LaserDisc players. The use of red laser diodes became widespread with the commercial success of modern DVD players, which use a 660 nm laser diode technology. Today, red and red-orange laser diodes are widely available to the public in the form of extremely inexpensive laser pointers. Portable, high-powered versions are also available for various applications.^[16] More recently, 671 nm diode-pumped solid state (DPSS) lasers have been introduced to the market for all-DPSS laser display systems, particle image velocimetry, Raman spectroscopy, and holography.^[17]

In nature[link]

Mars possesses a distinct red color, particularly when seen up close

Mars is called the Red Planet because of the reddish color imparted to its surface by the abundant iron oxide present there.^[18] Astronomical objects that are moving away from the observer exhibit a Doppler red shift. Jupiter's surface displays a Great Red Spot caused by an oval-shaped gigantic storm south of the planet's equator.^[19] Many elements exhibit a red color when burned: calcium, for example, produces a brick-red when combusted.^[20]

Oxygenated blood is red due to the presence of oxygenated hemoglobin.^[21] When used to describe natural animal coloration, "red" usually refers to a brownish, reddish-brown or ginger color. In this sense it is used to describe coat colors of reddish-brown cattle and dogs, and in the names of various animal species or breeds such as red fox, red squirrel, red deer, Robin redbreast, Red Grouse, Red Knot, Redstart, Redwing, Red Setter, Red Devon cattle, etc. This reddish-brown color is also meant when using the terms red ochre, red hair and Red Indian. The red herring dragged across a trail to destroy the scent gets its color from the heavy salting and slow smoking of the fish, which results in a warm, brown color. When used for flowers, red often refers to purplish (red deadnettle, red clover, red helleborine) or pink (red campion, red valerian) colors.

Red is associated with dominance in a number of animal species.^[22] For example, in mandrills, red coloration of the face is greatest in alpha males, increasingly less prominent in lower ranking subordinates, and directly correlated with levels of testosterone.^[23] Red can also affect the perception of dominance by others, leading to significant differences in mortality, reproductive success and parental investment between individuals displaying red and those not.^[24] In humans, wearing red has been linked with increased performance in competitions, including professional sport^[25][26] and multiplayer video games.^[27] Controlled tests have demonstrated that wearing red does not increase performance or levels of testosterone during exercise, so the effect is likely to be produced by perceived rather than actual performance.^[28] Judges of tae kwon do have been shown to favor competitors wearing red protective gear over blue,^[29] and, when asked, a significant majority of people say that red abstract shapes are more "dominant", "aggressive", and "likely to win a physical competition" than blue shapes.^[22] In contrast to its positive effect in physical competition and dominance behavior, exposure to red decreases performance in cognitive tasks^[30] and elicits aversion in psychological tests where subjects are placed in an "achievement" context (e.g., taking an IQ test).^[31]

Symbolism[link]

Emotions[link]

Artificial red poppies, worn in some countries to commemorate those who died in war

Red is used as a symbol of guilt, sin, passion, and anger, often as connected with blood or sex.^[32] A biblical example is found in Isaiah: "Though your sins be as scarlet, they shall be white as snow."^[33] Also, The Scarlet Letter, an 1850 American novel by Nathaniel Hawthorne, features a woman in a Puritan New England community who is punished for adultery with ostracism, her sin represented by a red letter 'A' sewn onto her clothes.^[34] This all comes from a general Hebrew view inherited by Christianity which associates red with the blood of murder,^[35] as well as with guilt in general. Often, objects meant to scare will be red.^[36] Another popular example is the phrase "caught red-handed", meaning either caught in an act of crime or caught with the blood of murder still on one's hands.^[37] At one one point, red became associated with prostitutes and brothels (red-light districts).^[38][39] In Roman Catholicism, red represents wrath, one of the Seven Deadly Sins. In Christianity, Satan is usually depicted as colored red and/or wearing a red costume in both iconography and popular culture.^[40] Statistics have shown that red cars are more likely to be involved in accidents.^[41]

The color red is associated with lust, passion, love, beauty, and danger. The association with love and beauty is possibly related to the use of red roses as a love symbol.^[42] Both the Greeks and the Hebrews considered red a symbol of love as well as sacrifice.^[43] Psychological research has shown that men find women who are wearing red more attractive.^[44]

Courage and sacrifice[link]

Red is used as a symbol of courage and sacrifice, as in blood spilt in sacrifice, or courage in the face of lethal danger.^[45] Examples are found in the flags of many nations, including the United States, as well as in the novel The Red Badge of Courage, in which a soldier in the American Civil War discovers the meaning of courage.^[46] In Christianity, red is the liturgical color for the feast of martyrs, representing the blood of those who suffered death for their faith. It is sometimes used as the liturgical color for Holy Week, including Palm Sunday and Good Friday, although this is a modern (20th century) development. It is also the liturgical color used to commemorate the Holy Spirit (for this reason it is worn at Pentecost and during Confirmation masses). Because of its association with martyrdom and the Spirit, it is also the color used to commemorate the Apostles (except for the Apostle St. John, who was not martyred, where white is used), and as such, it is used to commemorate bishops, who are the successors of the Apostles (for this reason, when funeral masses are held for bishops, cardinals, or popes, red is used instead of the white that would ordinarily be used). In Roman mythology red is associated with the god of war, Mars.^[45] A Roman general receiving a triumph had his entire body painted red in honor of his achievement.^[47] Red was also the traditional color of the uniforms worn by the British Army, and such British soldiers were often known as Redcoats. The phrase "red-blooded" describes someone who is audacious, robust, or virile.^[37] In Edward de Bono's book Six Thinking Hats, a red hat represents feelings and emotions.^[48]

Warning[link]

Stop sign used in various countries. The shape and color red is used nearly universally today.^{[citation needed]}

Red sky at night, sailor's/shepherd's delight.

Red catches people's attention and can be used either in a negative way to indicate danger and emergency, in a positive way in advertising to gain more viewers, or in nature, as a ripe fruit announces its ripeness by its red color.^[49] Several studies have indicated that red carries the strongest reaction of all the colors, with the level of reaction decreasing gradually with the colors orange, yellow, and white, respectively.^[50] Because of this, red is often used to catch people's attention in a variety of situations (see: penalty card).^[51]

The port, or left, side of a sea-faring vessel carries a red navigation light to warn other vessels approaching from that side to change course to avoid a collision.^[52] Red light is scattered the least among all colors of the visible spectrum and therefore reaches the greatest distance. Therefore, it is used to indicate "stop" in traffic signal lights.

Red in different cultures and traditions[link]

This section contains Chinese text. Without proper rendering support, you may see question marks, boxes, or other symbols instead of Chinese characters.

In China, red (simplified Chinese: 红; traditional Chinese: 紅; pinyin: hóng) is the symbol of fire and the south (both south in general and Southern China specifically). It carries a largely positive connotation, being associated with courage, loyalty, honor, success, fortune, fertility, happiness, passion, and summer.^[53][54] In Chinese cultural traditions, red is associated with weddings (where brides traditionally wear red dresses) and red paper is frequently used to wrap gifts of money or other objects. Special red packets (simplified Chinese: 红包; traditional Chinese: 紅包; pinyin: hóng bāo in Mandarin or lai see in Cantonese) are specifically used during Chinese New Year celebrations for giving monetary gifts. On the more negative side, obituaries are traditionally written in red ink, and to write someone's name in red signals either cutting them out of one's life, or that they have died.^[54] Red is also associated with either the feminine or the masculine (yin and yang respectively), depending on the source.^[54][55] The Little Red Book, a collection of quotations from Chairman Mao Tse-Tung, founding father of the People's Republic of China (PRC), was published in 1966 and widely distributed thereafter.

In Japan, red is a traditional color for a heroic figure.^[56] In the Indian subcontinent, red is the traditional color of bridal dresses, and is frequently represented in the media as a symbolic color for married women.^[57] The color is associated with purity, as well as with sexuality in marital relationships through its connection to heat and fertility.^[58] It is also the color of wealth, beauty, and the goddess Lakshmi.^[45]

In Central Africa, Ndembu warriors rub themselves with red paint during celebrations. Since their culture sees the color as a symbol of life and health, sick people are also painted with it. Like most Central African cultures, the Ndembu see red as ambivalent, better than black but not as good as white.^[59] In other parts of Africa, however, red is a color of mourning, representing death.^[60] Because red bears are associated with death in many parts of Africa, the Red Cross has changed its colors to green and white in parts of the continent.^[61]

The early Ottoman Turks led by the first Ottoman Sultan, Osman I, carried red banners symbolizing sovereignty, Ghazis and Sufism, until according to legend he saw a new red flag in his dream inlaid with a crescent.

In sports[link]

Teams throughout the world wear red on their uniforms. Numerous national sports teams wear red, often through association with their national flags. These include teams from Spain (with a soccer team nicknamed La Furia Roja or "The Red Fury"), Belgium (whose football team bears the nickname Rode Duivels or "Red Devils"), other examples being teams from England, Wales, Canada, Denmark, Tonga, Chile, Puerto Rico, Russia and Switzerland.

Major League Baseball is especially well known for red teams.^[62] The Cincinnati Red Stockings are the oldest professional baseball team, dating back to 1869.^[63] The franchise soon relocated to Boston and is now the Atlanta Braves, but its name survives as the origin for both the Cincinnati Reds and Boston Red Sox. During the 1950s when red was strongly associated with communism, the modern Cincinnati team was known as the "Redlegs" and the term was used on baseball cards. After the red scare faded, the team was known as the "Reds" again.^[64] The Los Angeles Angels of Anaheim are also known for their color red, as are the St. Louis Cardinals, Arizona Diamondbacks, and the Philadelphia Phillies.

In the NHL, red jerseys are worn by the Detroit Red Wings, Washington Capitals, Calgary Flames, Carolina Hurricanes, Chicago Blackhawks, Colorado Avalanche, Minnesota Wild, Montreal Canadiens, Ottawa Senators, Phoenix Coyotes, and the New Jersey Devils.

In association football, teams such as Manchester United, Bayern Munich, Liverpool, Arsenal, Toronto FC, and S.L. Benfica primarily wear red jerseys. Other teams that prominently feature red on their kits include AC Milan (nicknamed i rossoneri for their red and black shirts), AFC Ajax, Olympiacos, River Plate, Atletico Madrid, and Flamengo. A red card is issued to a player who commits a serious infraction: the player is immediately disqualified from further play and his team must continue with one less player for the game's duration.

In rugby union, Ireland's Munster rugby, New Zealand's Canterbury provincial team and the Crusaders Super 14 rugby side wear red as a major color in their playing strips.

In the NFL, teams with a shade of the color red as the primary color of either the team's dark "home" jersey (or an alternate thereof) or its "throwback" jersey include the Arizona Cardinals, Atlanta Falcons, Houston Texans, Kansas City Chiefs, New England Patriots, San Francisco 49ers, Tampa Bay Buccaneers, and Washington Redskins.

The Cleveland Cavaliers basketball team uses a deeper shade of red called wine. A fellow National Basketball Association team, the Los Angeles Clippers, wears red uniforms for road games, as do the Chicago Bulls, Atlanta Hawks, Portland Trail Blazers, and the Houston Comets of the WNBA. A similar shade to the Cavaliers' tone (known in this instance as claret) is used by the English association football teams Aston Villa, West Ham United, and Burnley.

In boxing, red is often the color used on a fighter's gloves. George Foreman wore the same red trunks he used during his loss to Muhammad Ali when he defeated Michael Moorer 20 years later to recuperate the title he lost. Boxers named or nicknamed "red" include Red Burman, Ernie "Red" Lopez, and his brother Danny "Little Red" Lopez.

Rosso Corsa is the red international motor racing color of cars entered by teams from Italy. Since the 1920s Italian race cars of Alfa Romeo, Maserati, Lancia, and later Ferrari and Abarth have been painted with a color known as rosso corsa ("racing red"). National colors were mostly replaced in Formula One by commercial sponsor liveries in 1968, but unlike most other teams, Ferrari always kept the traditional red, although the shade of the color varies.

On flags[link]

The red flag of the Soviet Union

Red is one of the most common colors used on national flags. The use of red has similar connotations from country to country: the blood, sacrifice, and courage of those who defended their country; the sun and the hope and warmth it brings; and the sacrifice of Christ's blood (in some historically Christian nations) are a few examples. Red is the color of the flags of several countries that once belonged to the former British Empire. The British flag bears the colors red, white, and blue; it includes the cross of Saint George, patron saint of England, and the saltire of Saint Patrick, patron saint of Ireland, both of which are red on white.^[65] The flag of the United States bears the colors of Britain,^[66] the colors of the French tricolore include red as part of the old Paris coat of arms, and other countries' flags, such as those of Australia, New Zealand, and Fiji, carry a small inset of the British flag in memory of their ties to that country.^[67] Many former colonies of Spain, such as Mexico, Colombia, Ecuador, Cuba, Puerto Rico, Peru, and Venezuela, also feature red-one of the colors of the Spanish flag-on their own banners. Red flags are also used to symbolize storms, bad water conditions, and many other dangers. Navy flags are often red and yellow. Red is prominently featured in the flag of the United States Marine Corps.

The red on the flag of Nepal represents the floral emblem of the country, the rhododendron.

Red, blue, and white are also the Pan-Slavic colors adopted by the Slavic solidarity movement of the late nineteenth century. Initially these were the colors of the Russian flag; as the Slavic movement grew, they were adopted by other Slavic peoples including Slovaks, Slovenes, and Serbs. The flags of the Czech Republic and Poland use red for historic heraldic reasons (see Coat of arms of Poland and Coat of arms of the Czech Republic) & not due to Pan-Slavic connotations. In 2004 Georgia adopted a new white flag, which consists of four small and one big red cross in the middle touching all four sides.

Red, white, and black are the colors of Pan-Arabism and are used by many Arab countries.^[68]

Red, gold, green, and black are the colors of Pan-Africanism. Several African countries thus use the color on their flags, including South Africa, Ghana, Senegal, Mali, Ethiopia, Togo, Guinea, Benin, and Zimbabwe. The Pan-African colors are borrowed from the flag of Ethiopia, one of the oldest independent African countries.^[68][69] Rwanda, notably, removed red from its flag after the Rwandan Genocide, because Pan-Africanism was so strongly associated with the event and because of red's association with blood.^[70]

The flag of Japan has a red circle in the middle. The flag of the Philippines has a red trapezoid on the bottom signifying blood, courage, and valor (also, if the flag is inverted so that the red trapezoid is on top and the blue at the bottom, it indicates a state of war). The flag of Singapore has a red rectangle on the top. The field of the flag of Portugal is green and red.

Use by political movements[link]

As early as the 9th century, the Khurramites (successors to the Mazdak religion and proto-communists in the Middle Ages of the Middle East) used red as their symbol for revolution. Even before Europe's Revolutions of 1848, Socialist red was used as a color of European Revolutionaries, often in the form of a red flag. It was also used by Garibaldi's camicie rosse (redshirts) in the Italian Risorgimento, and taken up by Leftist and generally revolutionary groups, while the white of legitimist Bourbon partisans became associated with pre-World War I conservatives. The red color recalls the term "blood of the workers", representing the suffering of the proletariat. For instance, the Civil War in Russia and the Civil War in Finland were fought between the Red Army and various White Armies.

Members of a People's Republic of China military honor guard.

The identification of Communism with Socialist red (with the red flag being the primary color of the flag of the Soviet Union) and the red star being a Communist emblem led to such Cold War phrases as "the Red Menace" and "Red China" (as distinguished from Nationalist China, "Blue China" or "Free China"). China's de-facto anthem under Mao Zedong was "The East Is Red".^[71] Mao Zedong was sometimes referred to as a "red sun".^[72] The color was also associated with political vehicles such as the Red Guard in China and the Red Guards during the Russian Revolution of 1917 as well as with left-wing paramilitary terrorist groups such as the Red Army Faction in Germany and the Japanese Red Army. Red remains associated with parties on the left of the political spectrum.

Social-democratic political parties throughout the world, particularly in Europe, are most commonly symbolized by the color red. Red is also the color associated with the Popular Democratic Party of Puerto Rico.

In the United States, red is associated with the center-right Republican Party and blue with the Democrats – a reverse of the traditional European scheme. This convention is relatively recent: before the 2000 presidential election, media outlets assigned red and blue (the colors of the American flag) to both parties, sometimes alternating the allocation for each election. Fixed usage was established during the 39-day recount following the 2000 election, when the media began to discuss the contest in terms of "red states" versus "blue states".^[73]

Food and drink[link]

Pommes d'amour

Most red foods derive from one of two sources. Plants like apples, strawberries, cherries, tomatoes, peppers, and pomegranates are often colored by forms of carotenoids, red pigments that were originally developed to assist photosynthesis.^[74] Red meat gets its color from the iron found in the myoglobin and hemoglobin in the muscles and residual blood.^[75]

Social and special interest groups[link]

Such names as Red Club (a bar), Red Carpet (a discothèque) or Red Cottbus and Club Red (event locations) suggest liveliness and excitement. The Red Hat Society is a social group founded in 1998 for women 50 and over.

Use of the color red to call attention to an emergency situation is evident in the names of such organizations as the Red Cross (humanitarian aid), Red Hot Organization (AIDS support), and the Red List of Threatened Species (of IUCN).

Corporate design[link]

Red is associated with a number of worldwide companies and brands which use the color prominently on their logos and advertisements, presumably because it is conspicuous and attracts attention. These include:

Airline logo

Car rental logo

Soft drink logo

Airline logo

Gas station logo

Cigarette logo

Store chain logo

Idioms[link]

Many idiomatic expressions exploit the various connotations of red:

Expressing emotion

• "to see red" (to be angry or aggressive)
• "to have red ears / a red face" (to be embarrassed)
• "to paint the town red" (to have an enjoyable evening, usually with a generous amount of eating, drinking, dancing)

Giving warning

• "to raise a red flag" (to signal that something is problematic)
• "like a red rag to a bull" (to cause someone to be enraged)
• "to be in the red" (from the accounting habit of writing deficits and losses in red ink)

Calling attention

• "a red-letter day" (commemorating a special or important event)
• "to print in red ink" (for emphasis or easy identification)
• "to lay out the red carpet" or "give red-carpet treatment" (to treat someone royally as a very special person)
• "to catch someone red-handed" (in the act of doing something wrong, such with blood on his hands after a murder or poaching game)
• "to tie up in red tape" (originally, a way to identify important administrative documents in an archive, now, excessive bureaucratic regulation)

In film[link]

Many movie titles have included the color's name, such as:

• The Woman in Red, a 1935 American film
• Reds, a 1981 film about Communism in the USA and Russia
• The Woman in Red, a 1984 American comedy film
• Raise the Red Lantern, a 1991 Chinese film directed by Zhang Yimou about a concubine
• Red, a Tamil movie from 2002
• Red, an American movie from 2008
• Red, an action comedy from 2010, starring Bruce Willis
• Red Dog, a 2011 Australian film

See also[link]

• Gules
• List of colors
• Red Riding Hood
• Scarlet (color)
• Variations of red

References[link]

Red & White Cigarette

External links[link]

• Seeing Red - slideshow by Life magazine

Find more about Red on Wikipedia's sister projects:
	Definitions and translations from Wiktionary
	Images and media from Commons
	Learning resources from Wikiversity
	News stories from Wikinews
	Quotations from Wikiquote
	Source texts from Wikisource
	Textbooks from Wikibooks