0_Wizard
I think blue is such a beautiful color! It's one of the three primary colors!
Blue is one of the three primary colours of pigments in painting and traditional colour theory, as well as in the RGB colour model.
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Blue
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Color mixing
There are two types of color mixing: "Additive" and "Subtractive". In both cases, there are three primary colors, three secondary colors (colors made from 2 of the three primary colors in equal amounts), and one tertiary color made from all three primary colors. This point is a common source of confusion, as there are different sets of primary colors depending on whether you are working with additive or subtractive mixing. The additive mixing of colors is unintuitive as it does not correspond to the mixing of physical substances (such as paint) which would correspond to subtractive mixing. For instance, one can additively mix yellow and blue by shining yellow light together with blue light, which will result in not green but a white light.
Complementary colors
Complementary colors are pairs of colors which, when combined, cancel each other out. This means that when combined, they produce a gray-scale color like white or black. When placed next to each other, they create the strongest contrast for those particular two colors. Due to this striking color clash, the term opposite colors is often considered more appropriate than "complementary colors". Which pairs of colors are considered complementary depends on the color theory one uses:  On the traditional color wheel developed in the 18th century, used by Claude Monet and Vincent van Gogh and other painters, and still used by many artists today, the primary colors were considered to be red, yellow, and blue, and the primary–secondary complementary pairs are red–green (Christmas), blue-orange (Westwood), and yellow–purple (Mesa High).
Color theory
In the visual arts, color theory or colour theory is a body of practical guidance to color mixing and the visual effects of a specific color combination. There are also definitions (or categories) of colors based on the color wheel: primary color, secondary color and tertiary color. Although color theory principles first appeared in the writings of Leone Battista Alberti (c.1435) and the notebooks of Leonardo da Vinci (c.1490), a tradition of "colory theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color ("Opticks", 1704) and the nature of primary colors.
Primary color
A set of primary colors is, most tangibly, a set of "real" physical pigmented media or colored lights that can be combined in varying amounts to produce a "gamut" of colors. This is the essential method used in applications that are intended to elicit the perception of diverse sets of color, e.g. electronic displays, color printing, and paintings. Perceptions associated with a given combination of primary colors are predicted by applying the appropriate mixing model (additive, subtractive, additive averaging etc.) that embodies the underlying physics of how light interacts with the media and ultimately the retina.
RGB color model
The RGB color model is an additive color model in which red, green and blue light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The main purpose of the RGB color model is for the sensing, representation and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors. RGB is a "device-dependent" color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual R, G, and B levels vary from manufacturer to manufacturer, or even in the same device over time.
Color wheel
A color wheel or colour circle is an abstract illustrative organization of color hues around a circle, which shows the relationships between primary colors, secondary colors, tertiary colors etc. Some sources use the terms "color wheel" and "color circle" interchangeably; however, one term or the other may be more prevalent in certain fields or certain versions as mentioned above. For instance, some reserve the term "color wheel" for mechanical rotating devices, such as color tops or filter wheels. Others classify various color wheels as "color disc", "color chart", and "color scale" varieties.
Comparison of color models in computer graphics
This article provides introductory information about the RGB, HSV, and HSL color models from a computer graphics (Web page, image) perspective. An introduction to colors is also provided to support the main discussion. First, "color" refers to the human brain's subjective interpretation of combinations of a narrow band of wavelengths of light. For this reason, the definition of "color" is not based on a strict set of physical phenomena. Therefore, even basic concepts like "primary colors" are not clearly defined. For example, traditional "Painter's Colors" use red, blue, and yellow as the primary colors, "Printer's Colors" use cyan, yellow, and magenta, and "Light Colors" use red, green, and blue.
1_Apprentice
Blue is an excellent color! What color would I have to combine it with to make purple?
0_Wizard
Red! You can also mix blue with green to make azure and blue and violet to make ultramarine! It's a very versatile color!
Most blues contain a slight mixture of other colors; azure contains some green, while ultramarine contains some violet.
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Blue
Blue is one of the three primary colours of pigments in painting and traditional colour theory, as well as in the RGB colour model. It lies between violet and green on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colors; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall scattering explains blue eyes.
Ultramarine
Ultramarine is a deep blue color and a pigment which was originally made by grinding lapis lazuli into a powder. The name comes from the Latin "ultramarinus", literally "beyond the sea", because the pigment was imported into Europe from mines in Afghanistan by Italian traders during the 14th and 15th centuries. Ultramarine was the finest and most expensive blue used by Renaissance painters. It was often used for the robes of the Virgin Mary, and symbolized holiness and humility. It remained an extremely expensive pigment until a synthetic ultramarine was invented in 1826. The pigment consists primarily of a zeolite-based mineral containing small amounts of polysulfides.
Blue–green distinction in language
Many languages do not distinguish between what in English are described as "blue" and "green" and instead use a cover term spanning both. To describe this English lexical gap, linguists use the portmanteau word "grue", from "green" and "blue", which the philosopher Nelson Goodman coined in his 1955 "Fact, Fiction, and Forecast" to illustrate the "new riddle of induction". The exact definition of "blue" and "green" may be complicated by the speakers not primarily distinguishing the hue, but using terms that describe other color components such as saturation and luminosity, or other properties of the object being described.
Red
Red is the colour at the end of the visible spectrum of light, next to orange and opposite violet. It has a dominant wavelength of approximately 625–740 nanometres. It is a primary color in the RGB color model and the CMYK color model, and is the complementary color of cyan. Reds range from the brilliant yellow-tinged scarlet and vermillion to bluish-red crimson, and vary in shade from the pale red pink to the dark red burgundy. The red sky at sunset results from Rayleigh scattering, while the red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide.
Violet (color)
Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a dominant wavelength of approximately 380-450 nanometers. Light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel historically used by painters, it is located between blue and purple. On the screens of computer monitors and television sets, a color which looks similar to violet is made, with the RGB color model, by mixing red and blue light, with the blue twice as bright as the red. This is not true violet, since it is composed of multiple longer wavelengths rather than a single wavelength shorter than that of blue light.
Shades of blue
Varieties of the color blue may differ in hue, chroma (also called saturation, intensity, or colorfulness), or lightness (or value, tone, or brightness), or in two or three of these qualities. Variations in value are also called tints and shades, a tint being a blue or other hue mixed with white, a shade being mixed with black. A large selection of these various colors is shown below. In this section, the term tint is used in its technical sense as used in color theory, meaning a blueish color mixed with white or light gray. Baby blue is known as one of the pastel colors. With a hue code of 199, this color is a tone of azure.
Color theory
In the visual arts, color theory or colour theory is a body of practical guidance to color mixing and the visual effects of a specific color combination. There are also definitions (or categories) of colors based on the color wheel: primary color, secondary color and tertiary color. Although color theory principles first appeared in the writings of Leone Battista Alberti (c.1435) and the notebooks of Leonardo da Vinci (c.1490), a tradition of "colory theory" began in the 18th century, initially within a partisan controversy over Isaac Newton's theory of color ("Opticks", 1704) and the nature of primary colors.
1_Apprentice
Amazing! how does crayola create all these different colors when there is only 3 primary colors?
0_Wizard
Exactly! I recently learned that the sky and deep sea only appear blue because of and optical effect called Rayleigh scattering. 
The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering.
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Blue
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Blue
Blue is one of the three primary colours of pigments in painting and traditional colour theory, as well as in the RGB colour model. It lies between violet and green on the spectrum of visible light. The eye perceives blue when observing light with a dominant wavelength between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colors; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called Tyndall scattering explains blue eyes.
Skyglow
Skyglow (or sky glow) is the diffuse luminance of the night sky, apart from discrete light sources such as the Moon and visible individual stars. It is a commonly noticed aspect of light pollution. While usually referring to sky luminance arising from artificial lighting, skyglow may also involve any nighttime sources of diffuse light, including natural ones like the zodiacal light, starlight, and airglow. In the context of light pollution, skyglow arises from the use of artificial light sources, including electrical (or rarely gas) lighting used for illumination and advertisement, and from gas flares.
Rayleigh scattering
Rayleigh scattering (pronounced ), named after the British physicist Lord Rayleigh (John William Strutt), is the (dominantly) elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the radiation. Rayleigh scattering does not change the state of material and is, hence, a parametric process. The particles may be individual atoms or molecules. It can occur when light travels through transparent solids and liquids, but is most prominently seen in gases. Rayleigh scattering results from the electric polarizability of the particles. The oscillating electric field of a light wave acts on the charges within a particle, causing them to move at the same frequency.
Eye color
Eye color is a polygenic phenotypic character determined by two distinct factors: the pigmentation of the eye's iris and the frequency-dependence of the scattering of light by the turbid medium in the stroma of the iris. In humans, the pigmentation of the iris varies from light brown to black, depending on the concentration of melanin in the iris pigment epithelium (located on the back of the iris), the melanin content within the iris stroma (located at the front of the iris), and the cellular density of the stroma. The appearance of blue and green, as well as hazel eyes, results from the Tyndall scattering of light in the stroma, a phenomenon similar to that which accounts for the blueness of the sky called Rayleigh scattering.
Mie scattering
The Mie solution to Maxwell's equations (also known as the Lorenz–Mie solution, the Lorenz–Mie–Debye solution or Mie scattering) describes the scattering of an electromagnetic plane wave by a homogeneous sphere. The solution takes the form of an infinite series of spherical multipole partial waves. It is named after Gustav Mie. The term "Mie solution" is also used for solutions of Maxwell's equations for scattering by stratified spheres or by infinite cylinders, or other geometries where one can write separate equations for the radial and angular dependence of solutions. The term "Mie theory" is sometimes used for this collection of solutions and methods; it does not refer to an independent physical theory or law.
Optics
Optics is the branch of physics which involves the behaviour and properties of light, including its interactions with matter and the construction of instruments that use or detect it. Optics usually describes the behaviour of visible, ultraviolet, and infrared light. Because light is an electromagnetic wave, other forms of electromagnetic radiation such as X-rays, microwaves, and radio waves exhibit similar properties. Most optical phenomena can be accounted for using the classical electromagnetic description of light. Complete electromagnetic descriptions of light are, however, often difficult to apply in practice.
Scattering
Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections that undergo scattering are often called "diffuse reflections" and unscattered reflections are called "specular" (mirror-like) reflections. Scattering may also refer to particle-particle collisions between molecules, atoms, electrons, photons and other particles.
1_Apprentice
Rayleigh scattering sounds quite scientific. I don't know much about it.
0_Wizard
It's a pretty complicated concept! Another crazy concept is the spectrum of visible light! Blue actually lies between violet and green on the spectrum.
It lies between violet and green on the spectrum of visible light.
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Rayleigh scattering
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Ultraviolet
Ultraviolet (UV) is an electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation constitutes about 10% of the total light output of the Sun, and is thus present in sunlight. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although it's not considered an ionizing radiation because its photons lack the energy to ionize atoms, long-wavelength ultraviolet radiation can cause chemical reactions and causes many substances to glow or fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules.
Fluorescent lamp
A fluorescent lamp, or fluorescent tube, is a low-pressure mercury-vapor gas-discharge lamp that uses fluorescence to produce visible light. An electric current in the gas excites mercury vapor, which produces short-wave ultraviolet light that then causes a phosphor coating on the inside of the lamp to glow. A fluorescent lamp converts electrical energy into useful light much more efficiently than incandescent lamps. The typical luminous efficacy of fluorescent lighting systems is 50–100 lumens per watt, several times the efficacy of incandescent bulbs with comparable light output. Fluorescent lamp fixtures are more costly than incandescent lamps because they require a ballast to regulate the current through the lamp, but the lower energy cost typically offsets the higher initial cost.
Infrared photography
In infrared photography, the film or image sensor used is sensitive to infrared light. The part of the spectrum used is referred to as near-infrared to distinguish it from far-infrared, which is the domain of thermal imaging. Wavelengths used for photography range from about 700 nm to about 900 nm. Film is usually sensitive to visible light too, so an infrared-passing filter is used; this lets infrared (IR) light pass through to the camera, but blocks all or most of the visible light spectrum (the filter thus looks black or deep red). ("Infrared filter" may refer either to this type of filter or to one that blocks infrared but passes other wavelengths.)
Electromagnetic radiation
In physics, electromagnetic radiation (EM radiation or EMR) refers to the waves (or their quanta, photons) of the electromagnetic field, propagating (radiating) through space-time, carrying electromagnetic radiant energy. It includes radio waves, microwaves, infrared, (visible) light, ultraviolet, X-rays, and gamma rays." Classically, electromagnetic radiation consists of electromagnetic waves, which are synchronized oscillations of electric and magnetic fields that propagate at the speed of light through a vacuum. The oscillations of the two fields are perpendicular to each other and perpendicular to the direction of energy and wave propagation, forming a transverse wave.
Electromagnetic spectrum
The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from below one hertz to above 10 hertz, corresponding to wavelengths from thousands of kilometers down to a fraction of the size of an atomic nucleus. 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.
Fluorescence
Fluorescence is the emission of light by a substance that has absorbed light or other electromagnetic radiation. It is a form of luminescence. In most cases, the emitted light has a longer wavelength, and therefore lower energy, than the absorbed radiation. The most striking example of fluorescence occurs when the absorbed radiation is in the ultraviolet region of the spectrum, and thus invisible to the human eye, while the emitted light is in the visible region, which gives the fluorescent substance a distinct color that can only be seen when exposed to UV light. Fluorescent materials cease to glow immediately when the radiation source stops, unlike phosphorescence, where they continue to emit light for some time after.
Light
Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight. Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), or 4.00 × 10 to 7.00 × 10 m, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths). This wavelength means a frequency range of roughly 430–750 terahertz (THz). The main source of light on Earth is the Sun. 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.
1_Apprentice
Is blue near the end of the light spectrum?
0_Wizard
I believe that it is! I think violet is at the end of the spectrum, like in a rainbow!
It lies between violet and green on the spectrum of visible light.
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Rainbow
A rainbow is a meteorological phenomenon that is caused by reflection, refraction and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. It takes the form of a multicoloured circular arc. Rainbows caused by sunlight always appear in the section of sky directly opposite the sun. Rainbows can be full circles. However, the observer normally sees only an arc formed by illuminated droplets above the ground, and centered on a line from the sun to the observer's eye. In a primary rainbow, the arc shows red on the outer part and violet on the inner side. This rainbow is caused by light being refracted when entering a droplet of water, then reflected inside on the back of the droplet and refracted again when leaving it.
List of Downton Abbey characters
This is a list of characters from Downton Abbey, a British period drama television series created by Julian Fellowes and co-produced by Carnival Films and Masterpiece for ITV and PBS, respectively. Robert Crawley, The 7th Earl of Grantham (also known as Lord Grantham) (played by Hugh Bonneville) was born in 1866 at Downton Abbey. His parents are the late 6th Earl of Grantham and the Dowager Countess of Grantham, Violet Crawley. He has a sister named Rosamund. Despite the family's financial situation, Robert's education was privileged and he was tutored from ages 7 to 13, before attending Eton and then Christ Church, Oxford, where he studied philosophy.
Violet (color)
Violet is the color at the end of the visible spectrum of light between blue and the invisible ultraviolet. Violet color has a dominant wavelength of approximately 380-450 nanometers. Light with a shorter wavelength than violet but longer than X-rays and gamma rays is called ultraviolet. In the color wheel historically used by painters, it is located between blue and purple. On the screens of computer monitors and television sets, a color which looks similar to violet is made, with the RGB color model, by mixing red and blue light, with the blue twice as bright as the red. This is not true violet, since it is composed of multiple longer wavelengths rather than a single wavelength shorter than that of blue light.
Purple
Purple is a color intermediate between blue and red. It is similar to violet, but unlike violet, which is a spectral color with its own wavelength on the visible spectrum of light, purple is a composite color made by combining red and blue. According to surveys in Europe and the U.S., purple is the color most often associated with royalty, magic, mystery and piety. When combined with pink, it is associated with eroticism, femininity and seduction. Purple was the color worn by Roman magistrates; it became the imperial color worn by the rulers of the Byzantine Empire and the Holy Roman Empire, and later by Roman Catholic bishops.
Indigo
Indigo is a deep and rich color close to the color wheel blue (a primary color in the RGB color space), as well as to some variants of ultramarine. It is traditionally regarded as a color in the visible spectrum, as well as one of the seven colors of the rainbow: the color between blue and violet; however, sources differ as to its actual position in the electromagnetic spectrum. The color indigo is named after the indigo dye derived from the plant "Indigofera tinctoria" and related species. The first known recorded use of indigo as a color name in English was in 1289. Species of "Indigofera" were cultivated in East Asia, Egypt, India, and Peru in antiquity.
Atmospheric optics
Atmospheric optics deals with how the unique optical properties of Earth's atmosphere cause a wide range of spectacular optical phenomena. The blue color of the sky is a direct result of Rayleigh scattering, which redirects higher frequency (blue) sunlight back into the field of view of the observer. Because blue light is scattered more easily than red light, the Sun takes on a reddish hue when it is observed through a thick atmosphere, as during a sunrise or sunset. Additional particulate matter in the sky can scatter different colors at different angles, creating colorful, glowing skies at dusk and dawn.
Rainbow Brite
Rainbow Brite, also known in Japan as , is a media franchise by Hallmark Cards, introduced in 1983. The animated television series of the same name first aired in 1984, the same year Hallmark licensed Rainbow Brite to Mattel for a range of dolls and other merchandise. A theatrical feature-length film, "Rainbow Brite and the Star Stealer", was released by Warner Bros. in 1985. The franchise was rebooted in 1996, 2003, 2009, and then again in 2014 through Hallmark's online on-demand streaming video service, Feeln. 2015 also saw with it a line of new merchandise sold only by Hallmark online and in its shops.
1_Apprentice
Ah, that would make sense why we see violet last in the rainbow. Have you ever found a pot of gold at the end of the rainbow? I have. It was filled with used up lottery tickets.