Optics , orange is a range of colours between red and yellow In
optics, orange is the colour seen by the eye when looking at light with a wavelength between approximately 585–620
nm. It has a
hue of 30° in
HSV colour space. Isaac Newton's
Opticks distinguished between pure orange light and mixtures of red and yellow light by noting that mixtures could be separated using a prism. In the traditional colour wheel used by painters, orange is the range of colours between red and yellow, and painters can obtain orange simply by mixing red and yellow in various proportions; however these colours are never as vivid as a pure orange pigment. In the
RGB colour model (the system used to display colours on a television or computer screen), orange is generated by combining high intensity red light with a lower intensity green light, with the blue light turned off entirely. Orange is a
tertiary colour which is numerically halfway between
gamma-compressed red and yellow, as can be seen in the
RGB colour wheel. Regarding painting, blue is the complementary colour to orange. As many painters of the 19th century discovered, blue and orange reinforce each other. The painter Vincent van Gogh wrote to his brother Theo that in his paintings, he was trying to reveal "the oppositions of blue with orange, of red with green, of yellow with violet... trying to make the colours intense and not a harmony of grey". In another letter he wrote simply, "There is no orange without blue." Van Gogh,
Pierre-Auguste Renoir and many other
Impressionist and
Post-Impressionist painters frequently placed orange against azure or cobalt blue, to make both colours appear brighter. The actual complement of orange is
azure – a colour that is one quarter of the way between blue and green on the colour spectrum. The actual complementary colour of true blue is yellow. Orange pigments are largely in the
ochre or
cadmium families, and absorb mostly greenish-blue light.
Pigments and dyes File:Orpiment mineral.jpg|A sample of
orpiment from an arsenic mine in
southern Russia. Orpiment has been used to make orange pigment since ancient times in ancient Egypt, Europe and China. Romans used the mineral for trade. File:Realgar09.jpg|
Realgar, an arsenic sulphide mineral 1.5-2.5 Mohs hardness, is highly toxic. It was used since ancient times until the 19th century to make red-orange pigment, as a poison, and a medicine. File:Crocoite from the Dundas extended mine, Dundas, Tasmania, Australia.jpg|A sample of
crocoite crystals from
Dundas extended mine in
Tasmania. Discovered in 1797 by the French chemist
Louis Vauquelin, it was used to make the first synthetic orange pigment,
chrome orange, used by
Pierre-Auguste Renoir and other painters. File:Safran-Weinviertel Niederreiter 2 Gramm 8285.jpg|
Saffron, made from the hand-picked
stigmas of the
Crocus sativus flower, is used both as a dye and as a spice. File:Curcuma longa (Haldi) W IMG 2440.jpg|The
Curcuma longa plant is used to make
turmeric, a common and less expensive substitute for saffron as a dye and colour. File:Curcuma longa roots.jpg|
Turmeric powder, first used as a dye, and later as a medicine and spice in
Indian cuisine. Other orange pigments include: •
Minium and
massicot are bright yellow and orange pigments made since ancient times by heating lead oxide and its variants. Minium was used in the
Byzantine Empire for making the red-orange colour on illuminated manuscripts, while massicot was used by ancient Egyptian scribes and in the Middle Ages. Both substances are toxic, and were replaced in the beginning of the 20th century by chrome orange and cadmium orange. •
Isatis tinctoria (woad) and
Rubia tinctorum (madder) were combined in the late 19th century to make orange pigment. •
Cadmium orange is a synthetic pigment made from
cadmium sulphide. It is a by-product of mining for
zinc, but also occurs rarely in nature in the mineral
greenockite. It is usually made by replacing some of the
sulphur with
selenium, which results in an expensive but deep and lasting colour.
Selenium was discovered in 1817, but the pigment was not made commercially until 1910. •
Quinacridone orange is a synthetic organic pigment first identified in 1896 and manufactured in 1935. It makes a vivid and solid orange. •
Diketopyrrolopyrrole orange or DPP orange is a synthetic organic pigment first commercialised in 1986. It is sold under various commercial names, such as translucent orange. It makes an extremely bright and lasting orange, and is widely used to colour plastics and fibres, as well as in paints.
Orange natural objects The orange colour of
carrots,
pumpkins,
sweet potatoes,
oranges, and many other fruits and vegetables comes from
carotenes, a type of
photosynthetic pigment. These pigments convert the light energy that the plants absorb from the sun into chemical energy for the plants' growth. The carotenes themselves take their name from the carrot.
Autumn leaves also get their orange colour from carotenes. When the weather turns cold and production of green
chlorophyll stops, the orange colour remains. Before the 18th century, carrots from Asia were usually purple, while those in Europe were either white or red. Dutch farmers bred a variety that was orange; according to some sources, as a tribute to the
stadtholder of
Holland and
Zeeland,
William of Orange. The long orange Dutch carrot, first described in 1721, is the ancestor of the orange horn carrot, one of the most common types found in supermarkets today. It takes its name from the town of
Hoorn, in the Netherlands. File:CarrotDiversityLg.jpg|Carrots, pumpkins and other vegetables get their orange colour from
carotenes, a variety of
photosynthetic pigment, which takes its own name from the carrot. File:Japanese maple.jpg|A
Japanese maple tree in autumn.
Autumn leaves also get their orange colour from carotenes. File:Traugers-farm-bucks-county-large.jpg|
Pumpkins File:CarrotRoots.jpg|
Carrots File:Orange peel fungi on Schwarzwald forestry road.jpg|Orange peel fungus (Aleuria aurantia) on a forestry road File:5aday sweet potato.jpg|
Sweet potatoes File:Orange-Fruit-Pieces.jpg|
Oranges File:Mandarin Oranges (Citrus Reticulata).jpg|
Mandarins Flowers Orange is traditionally associated with the
autumn season, with the harvest and autumn leaves. The flowers, like orange fruits and vegetables and autumn leaves, get their colour from the photosynthetic pigments called
carotenes. File:California Poppies1.jpg|A field of
California poppies File:Calendula officinalis 0.0 R.jpg|The
marigold flower, or
Calendula File:- Flower 19 -.jpg|Poppy flower File:Daylily (Hemerocallis fulva) v2.jpg|Daylily (
Hemerocallis fulva) File:Begonia 'On Top Sunset Shades' 01.JPG|Begonia cultivar File:Sylvia Ball-Dahlie.JPG|The
dahlia File:Orange Rose1.jpg|An orange
rose File:Orange hibiscus.jpg|alt=Orange hibiscus|Orange
hibiscus File:Butterfly Weed Asclepias tuberosa Buds.jpg|buds of the butterfly weed, or
Asclepias tuberosa File:Hieracium aurantiacum LC0106.jpg|
Hieracium aurantiacum, or orange hawkweed File:Heliconia psittacorum 01.JPG|
Heliconia psittacorum, or parrot's flower, is a perennial herb native to the Caribbean and northern South America. File:Fritillaria imperialis 01.JPG|
Fritillaria imperialis File:Yellow French Marigold Flower.jpg|
Tagetes erecta (marigold) File:Vanda garayi.png|
Vanda garayi Animals File:Canario paxaro.jpg|
Canary bird File:Panthera tigris tigris.jpg|A
Bengal tiger (
Panthera tigris tigris) File:Red Squirrel - Lazienki.JPG|A
red squirrel is actually orange. File:Vulpes vulpes laying in snow.jpg|A
red fox, or
Vulpes vulpes, in the snow. File:Iguana iguana (orange male).jpg|An
iguana File:A couple of Tadorna ferruginea.2.jpg|The
Tadorna ferruginea, or ruddy shelduck, lives in Southeast Europe, Central Asia and Southeast Asia, and migrates in the winter to India. File:Flamingo National Zoo.jpg|An orange
flamingo in the
National Zoo in Washington, D.C. File:Altamira Oriole icterus gularis, Bentsen State Park TX.jpg|An
Altamira oriole in Bentsen State Park, Texas. File:Flame angelfish (Centropyge loricula).jpg|A
flame angelfish, or
Centropyge loricula File:Auftauchender Koi 2011.JPG|A
koi, a domesticated
carp bred in Japan for its ornamental value in gardens and ponds File:Arion rufus (Dourbes).jpg|An
Arion rufus, or European red slug, lives in northern Europe, especially Denmark, and can be eighteen centimetres long.
Foods Orange is a very common colour of fruits, vegetables, spices, and other foods in many different cultures. As a result, orange is the colour most often associated in western culture with taste and aroma. Orange foods include peaches,
apricots,
mangoes,
carrots,
shrimp,
salmon roe, and many other foods. Orange colour is provided by
spices such as
paprika,
saffron and
curry powder. In the United States, with
Halloween on 31 October, and in North America with
Thanksgiving in October (Canada) and November (US) orange is associated with the harvest colour, and also is the colour of the carved pumpkins, or jack-o-lanterns, used to celebrate the holiday. File:Pumpkin-Pie-Whole-Slice.jpg|Orange-coloured
pumpkin pie is the traditional dessert at a US
Thanksgiving dinner. File:Melon au vin muscat.jpg|A
melon with
Muscat wine (France). File:Mashedpumpkin.jpg|A bowl of
mashed pumpkin File:TzimmesS.jpg|Carrot
tzimmes File:Apricots real.jpg|
Apricots File:Oronges.jpg|
Amanita caesarea known in English as Caesar's mushroom File:Salmon Fish.JPG|
Salmon steaks File:Mangga gedong mango juice.JPG|
Mango juice File:Homemade marmalade, England.jpg|Homemade English
marmalade File:Khrenovina-sauce.jpg|
Khrenovina sauce, a traditional
Siberian sauce made of tomatoes, garlic and horseradish. File:Paella valenciana.gif|
Paella from
Valencia, Spain File:Indian cuisine-Panipuri-05.jpg|
Panipuri, a popular street snack in the Indian subcontinent File:Curry Ist.jpg|
Curry powder from the Indian subcontinent File:Spanishsmokedpaprika.jpg|
Paprika from Spain
Food colourings , like many popular snack foods, contain
Yellow 6,
Yellow 5 and
Red 40 synthetic food colour. are now often coloured with
annatto, a natural food colour made from the seeds of the
achiote tree. People associate certain colours with certain
flavours, and the colour of food can influence the perceived flavour in anything from
candy to
wine. Since orange is popularly associated with good flavour, many companies add orange
food colouring to improve the appearance of their packaged foods. Orange pigments and dyes, synthetic or natural, are added to many orange sodas and juices, cheeses (particularly
cheddar cheese,
Gloucester cheese, and
American cheese); snack foods, butter and margarine; breakfast cereals, ice cream,
yoghurt, jam and candy. It is also often added to children's medicine, and to
chicken feed to make the
egg yolks more orange. The United States Government and the
European Union certify a small number of synthetic chemical colourings to be used in food. These are usually
aromatic hydrocarbons, or
azo dyes, made from petroleum. The most common ones are: •
Allura red AC, also known as Red 40 and
E129. •
Sunset Yellow FCF, also known as Yellow 6 and
E110. •
Tartrazine, also known as Yellow 5 and
E102. A dye used in soft drinks such as
Mountain Dew,
Kool-Aid, chewing gum, popcorn, breakfast cereals, cosmetics, shampoos, eyeshadow, blush, and lipstick. •
Orange B is approved by the US
Food and Drug Administration, but only for hot dog and sausage casings. •
Citrus Red 2 is certified only to colour orange peels. Because many consumers are worried about possible health consequences of synthetic dyes, some companies are beginning to use natural food colours. Since these food colours are natural, they do not require any certification from the Food and Drug Administration. The most popular natural food colours are: •
Annatto, made from the seeds of the
achiote tree. Annatto contains
carotenoids, the same ingredient that gives carrots and other vegetables their orange colour. Annatto has been used to dye certain cheeses in Britain, particularly
Gloucester cheese, since the 16th century. It is now commonly used to colour American cheese, snack foods, breakfast cereal, butter, and margarine. It is used as a body paint by native populations in Central and South America. In India, women often put it, under the name
sindūra, on their hairline to indicate that they are married. •
Turmeric is a common spice in the Indian subcontinent, Persia and the Mideast. It contains the pigments called
curcuminoids, widely used as a dye for the robes of Buddhist monks. It is also often used in curry powders and to give flavour to
mustard. It is now being used more frequently in Europe and the US to give an orange colour to canned beverages, ice cream, yogurt, popcorn and breakfast cereal. The food colour is usually listed as E100. •
Paprika oleoresin contains natural carotenoids, and is made from
chilli peppers. It is used to colour cheese, orange juice, spice mixtures and packaged sauces. It is also fed to chickens to make their
egg yolks more orange. ==Culture, associations and symbolism==