From the shimmering green of leaves on a forest tree to the deep azure of the oceans, vibrant color fills our world — but it’s more than just pretty to look at. Often there are fascinating stories behind the colors that exist both in nature and in human artifacts, whether they’re school bus yellow, Golden Gate Bridge orange, or the blue-green of surgical scrubs. Below, we’ve rounded up some of our most dazzling stories about color from around the rainbow (and beyond).

Original photo by nmedia/ Shutterstock

The Color Orange Is Named After the Fruit

Close-up of cut up fresh oranges. — Credit: Sheraz Shaikh/ Unsplash

The word “orange” refers to both a citrus fruit and the color of said fruit, so which usage came first? The color isn’t exclusive to the fruit, of course, but the term did come from it. The first use of “orange” as a color in English dates back to the 15th century, and was derived from pomme d’orenge, the French word for the citrus.

“Orange” started appearing in written English works as a color around the 16th century. Before that, English speakers just described it as “yellow-red.” Renowned 14th-century author Geoffrey Chaucer didn’t even have a singular word to describe a fox in his famous work The Canterbury Tales: “His colour was bitwixe yelow and reed [sic].”

Hollywood Uses Green Screens Because of Human Skin Tones

Dslr camera with green screen on the tripod. — Credit: kurgenc/ Shutterstock

If you’ve seen any big-budget Hollywood film, it probably used some variety of green screen-enabled special effects. In fact, some version of green screen technology, also known as “chroma keying,” has been around since the early days of film. The reason why screens are green is actually pretty simple — human skin is not green. When a camera analyzes chrominance, or color information, it can easily separate green (or blue) from the rest of the shot so that a video backdrop can be inserted.

However, the technology isn’t foolproof, as green clothes can blend in with backgrounds. (That’s why meteorologists don’t wear green on St. Patrick’s Day.) Because of this deficiency, among other reasons, some productions are shifting to high-tech LED panels to recreate otherworldly locations.

The First Color Humans Can Perceive Is Red

A baby laying on a red blanket. — Credit: Master the moment/ Shutterstock

After only a few weeks of life, babies begin to distinguish their first color (after white and black) — red. Humans perceive color thanks to three types of cones found in our eyes, each tuned to short (blue), medium (green), and long (red) wavelengths. Although cones perceive color from birth, it takes time for the human brain to make sense of those inputs. Because an infant’s vision is blurry during the first few weeks of life, red is the only color capable of being captured by the retina when viewed around 12 inches from a baby’s face. At around 2 months old, babies can begin to distinguish between reds and greens, followed closely by yellows and blues a few weeks later.

Some People Can See Nearly 100 Million Colors

Abstract colorful background. — Credit: Gegham Davtyan/ Shutterstock

Researchers estimate that some 300 million people around the world are colorblind, most of them male. On the opposite end of the spectrum are those with an exceedingly rare genetic condition that allows them to see nearly 100 million colors — or 100 times as many as the rest of us. It’s called tetrachromacy, or “super vision,” and it’s the result of having four types of cone cells in the retina rather than the usual three. Because of the way the condition is passed down via the X chromosome, the mutation occurs exclusively in women.

One tetrachromat describes her ability this way: “If you and I look at a leaf, I may see magenta running around the outside of the leaf or turquoise in certain parts where you would just see dark green. Where the light is making shadows on the walls, I’m seeing violets and lavenders and turquoise. You’re just seeing gray.” In short, tetrachromats see colors within colors, and even the tiniest change in the color balance of a particular hue will be apparent to them. It's estimated that 12% of women have a fourth retina cone, but only a fraction of them experience tetrachromacy. In total, only about 1% of humans have the condition.

Black Isn’t Technically a Color

Black paint and brush on a wood background. — Credit: Ilya Karnaukhov/ Shutterstock

Picture a rainbow, which comprises the visible spectrum of light, and you’ll notice that black isn’t in it. Scientifically speaking, black is the absence of light, and because light is required for color, black contains no color. (Black’s opposite, white, is the total of all colors of the visible spectrum.)

However, people usually think of black as a color in an artistic sense: as a pigment that absorbs visible light and reflects almost none, approximating the absence of light. Thus, the “black” we see is really a reflection of a mix of very dark colors. Here’s another mind-bending fact: Nothing in nature can be pure, absence-of-light black except the inner reaches of a black hole (although researchers have come close with Vantablack and other materials).

Blue Eyes Aren’t Actually Blue

Close-up of a woman with blue eyes. — Credit: Ashwin Vaswani/ Unsplash

Between 6,000 and 10,000 years ago, all humans had brown eyes, until a single genetic mutation caused one human to be born without the usual brown-black melanin pigment that colors irises brown. Irises without this pigment experience what’s known as the Tyndall effect. Because of blue’s short wavelength, that spectrum of light is reflected most by the fibers in the iris, causing eyes to take on a bluish color even though there is no blue pigment present. Today about 10% of the world’s population has blue eyes, though that number is skewed heavily by northern Europeans. In Finland and Estonia, for example, 89% of people have blue eyes — the highest percentage in the world. The U.S. comes in much lower, at around 27%.

Human Eyes Are Most Sensitive to the Green Wavelength of Light

Beams of light refracting and creating a rainbow spectrum. — Credit: Andrew E Gardner/ Shutterstock

Electromagnetic radiation comes in a variety of types, including radio waves, gamma rays, and visible light. The human eye can perceive wavelengths around 380 to 740 nanometers (nm), also known as the visual light range. The size of the wavelength determines the color we see: For example, at 400 nm our eyes perceive the color violet (hence the name “ultraviolet” for wavelengths directly under 400 nm), whereas at 700 nm our eyes glimpse red (but can’t see the “infrared” wavelengths just beyond it).

In the middle of this spectrum of visible light is the color green, which occupies the range from 520 to 565 nm and peaks at 555 nm. Because this is right in the middle of our visual range, our eyes are particularly sensitive to the color under normal lighting conditions, which means we can more readily differentiate among different shades of green. Scientists have also found that the color green positively affects our mood in part because our visual system doesn’t strain to perceive the color — which allows our nervous system to relax.

There’s a Good Reason School Buses Are Yellow

View of a school bus coming up a mountain. — Credit: Denisse Leon/ Unsplash

Glimpse a fleet of buses parked at any U.S. public school, and you’ll notice they’re all the same deep yellow — and it’s been that way for nearly a century. In an effort to standardize school bus construction around the country, thus ideally making them both safer and cheaper to mass-produce, school transportation officials met at Columbia University in 1939 to discuss a universal color for these vehicles. Fifty shades were hung up on the walls, ranging from lemon to deep orange. The color that was finally selected — known today as National School Bus Glossy Yellow, or Color 13432 — was chosen because of its ability to stand out from the background. Education officials didn’t know it at the time, but Color 13432 is wired to capture our attention, as the shade stimulates two of the three types of cones in the human eye — sending double the transmission to the brain compared to many other colors. That’s one reason a big yellow school bus is just so hard to miss.

Your Blue Veins Are Actually an Illusion

Protruding veins on female hands close-up. — Credit: Mariia Kurlova/ Shutterstock

Look at your arm, and you’ll see blue veins crisscrossing just beneath the skin. That’s an optical illusion. Human veins are not blue, and are actually transparent. While deoxygenated blood is a darker hue of red (which you’ve likely seen if you’ve ever donated blood or had blood drawn), the blue color comes from your skin scattering light, so that we perceive the veins beneath the skin as blue. The color perception of veins can also change depending on skin tone, as darker skin will turn veins more of a greenish color. While blue blood doesn’t occur naturally in humans, it is found in animals such as the horseshoe crab (whose blue blood has saved countless human lives). This family of crab sports blue blood because it contains copper pigments instead of iron.

The Golden Gate Bridge’s Orange Color Wasn’t Planned

View of the Golden Gate Bridge. — Credit: Patrick Tomasso/ Shutterstock

San Francisco’s Golden Gate Bridge, completed in 1937, has a bright earthy tone dubbed “international orange” — but when construction began in 1933, it was on track to be a boring, standard bridge color like black or silver (although the Navy also suggested yellow and black stripes so that it would be highly visible for ships). Consulting architect Irving Morrow noticed that some of the beams were primed in a reddish-orange color, and made it his personal mission to bring a similar shade to the finished product.

The warm color, he argued, was uniquely suited to San Francisco. It would stand out even on foggy days, and when the sun was out, the hue would pop against the blue sky and water. Such a distinct look would highlight the massive scale and stunning architecture of the bridge.

Morrow made his case to the Department of War, the permitting agency for the bridge, in 1935, and successfully convinced them. Today, the color gets touched up in small segments, since repainting the whole bridge would be a massive undertaking.

Want to replicate the bridge’s tone in your own home? The exact mix is on the bridge’s website.

According to Astronomers at Johns Hopkins, the Color of the Universe Is “Cosmic Latte”

Cosmic Latte solid color. — Credit: Giffany/ Shutterstock

We tend to think of space as cold and dark, but that’s only because most stars are light-years away from the pale blue dot we call home. The universe is actually quite bright on the whole, and its color has been given an appropriately celestial name: “cosmic latte.” In 2002, astronomers at Johns Hopkins University determined the shade after studying the light emitted by 200,000 different galaxies. They held a contest to give the result — a kind of creamy beige — its evocative moniker. (Other entries in the contest included “univeige” and “skyvory.”)

As with just about everything in the universe, however, the color isn’t fixed: It’s become less blue and more red over the last 10 billion years, likely as a result of redder stars becoming more prevalent. In another 10 billion years, we may even need to rename the color entirely.

The Sky Is Blue Because of the Color’s Wavelength

View of a beautiful blue sky. — Credit: Kumiko SHIMIZU/ Unsplash

The sun sends its rays to Earth as white light, meaning they contain everything in the color spectrum (red, orange, yellow, green, blue, indigo, violet). But blue is unlike the other colors, because its specific wavelength (between 450 and 495 nm) is more frequently scattered by particles in the atmosphere in a process known as Rayleigh scattering. At midday, the sky is pale blue as the sun’s light travels through less of the atmosphere, but as the sun heads toward the horizon, the sky becomes a richer blue because light travels through more of the atmosphere (thus scattering more blue light).

However, this is only half of the answer, because indigo and violet have even shorter wavelengths than blue, which raises the question: Why isn’t the sky violet? Figuring out this conundrum means taking a closer look at the human eye. The cones inside the eye are coded to perceive red, green, and blue, and it’s the combinations of these inputs that determine variations of color. Because of the eye’s sensitivity to the color blue, the sky takes on that particular hue instead of violet. Other animals likely perceive the sky (and the rest of the world) in a different hue because most mammals have only two different types of cones.

Yellow Pages Were Created Because a Printer Ran Out of White Paper

Hand pointing an advertisement in Yellow Pages. — Credit: Michal Mrozek/ Shutterstock

One day in 1883, Cheyenne, Wyoming-based printer Reuben H. Donnelley was busy printing the latest edition of the phone directory when he unexpectedly ran out of white paper. Unwilling to put off production until he could restock, he instead resorted to finishing the job with yellow paper, unknowingly creating an icon of the then-nascent information age. After subscribers commented on how these yellow pages were easy to find amid piles of white-hued publications, Donnelley produced the first official Yellow Pages phone book three years later. Using the color yellow for telephone business directories then became the norm around the world.

Red Is the Most Common Color on National Flags

National flags of various countries flying in the wind. — Credit: artpage/ Shutterstock

Purple is the least common color found on national flags (gracing only the banner of the Caribbean country Dominica), while red is the opposite, and can be found on a whopping 74% of flags, according to Guinness World Records. Around 50% of these flags use red to represent the blood of those who fought for the country, extolling the virtues of bravery and valor. This includes the U.S. flag, with the red standing for “hardiness and valor.” Meanwhile, when red is considered alongside vexillology’s second-favorite color, blue, only nine countries in the world (out of 196 total) have flags without red and/or blue in them.

No One Is Sure Why the Backstage Room Is Called a “Green Room”

A dressing table in a "green room" back stage. — Credit: Pixel-Shot/ Shutterstock

One early reference to a “green room” in the sense of a waiting room appears in The Diary of Samuel Pepys, the famed journal kept by a civil servant in 1660s London. Pepys mentions a “green room” when going to meet the royal family — likely a reference to the color of the walls. A “green room” was then tied to the theater in English playwright Thomas Shadwell’s 1678 comedy A True Widow, which includes the line: “Selfish, this Evening, in a green Room, behind the Scenes.” However, Shadwell doesn’t mention why it was called a green room. One notable London theater did have a dressing room covered in green fabric, but other theories behind the term reference actors going “green” because of nervousness, amateur or young (aka “green”) actors, or a place where early actors literally waited “on the green” lawns of outdoor theaters — among many other ideas. It’s possible we’ll never know the origin of the phrase for sure.

Pink Was Once Considered a Color for Baby Boys, While Blue Was for Baby Girls

Baby accessories in blue and pink. — Credit: Inspiration GP/ Shutterstock

Before pink and blue, there was white. For much of the 19th century, most infants and toddlers wore white dresses regardless of their biological sex. Dresses facilitated diaper-changing, after all, and white cotton could easily be cleaned with bleach. But around 1900, childcare experts began to push for a greater distinction between little girls and boys, amid fears that boys were growing up “weaker” and “lazier” than their fathers had. Many U.S. publications and stores responded in part by recommending pink clothing for boys and blue clothing for girls, although some also recommended the opposite color scheme. According to Dressmaker magazine, “Blue is reserved for girls as it is considered paler, and the more dainty of the two colors, and pink is thought to be stronger (akin to red).”

But around World War II, everything changed. Soon pink was heavily marketed as the preferred color for girls, and blue for boys. It’s not entirely clear what led to the switch, and the colors chosen were somewhat arbitrary — the focus was primarily on creating clothes specific for each child in an attempt to curb hand-me-downs, and thus sell more product. Once the 1950s began, hospitals wrapped newborns in pink or blue blankets, based on their sex (today’s standard blankets contain pink and blue stripes). All of this likely didn’t matter much to the babies themselves: Research has shown that children generally do not become conscious of their gender until age 3 or 4.

The Color Purple Technically Doesn’t Exist

Purple paint cans aerial view. — Credit: Anna Mente/ Shutterstock

Our eyes perceive color in the visible spectrum due to particular wavelengths, and violet is the shortest, at 380 nm. This is why the invisible wavelengths just below this threshold are known as ultraviolet, or UV rays (and why wavelengths directly above 700 nm are known as “infrared”).

The color purple, however, is what physicists call a “nonspectral color,” meaning it isn’t represented by a particular wavelength of light, but is instead a mixture of them as perceived by our brain. While some people use violet and purple interchangeably, the two colors are distinct; violet (which is part of the visible spectrum) has a more bluish hue, whereas purple is more red. The cones in our eyes receive inputs, and our brain uses ratios of these inputs to represent subtleties of color. Purple is therefore a complete construction of our brain, as no wavelength represents the color naturally. But purple isn’t alone — the same can be said for other colors such as black and white, as well as particular hues mixed with gray scale, such as pink and brown.

The Sky Looks Bluer in the Fall

Colorful autumn trees landscape during the fall season. — Credit: logoboom/Shutterstock

Although the sky is blue throughout the year, it’s often a richer blue in the fall and winter, especially in latitudes farther from the equator. Why? Well, the answer has to do with both electromagnetism and the biology of the human eye. As a refresher: When sunlight enters Earth’s atmosphere, gas and dust particles reflect the shorter wavelengths of visible light (such as blue) more than longer wavelengths (such as red). That — and the sensitivity of the human eye to the color blue — is why the sky appears as a cool sapphire.

However, as the seasons progress, one part of this equation changes: the sun’s position. As the sun gets lower and lower in the sky during its annual journey back toward the equator (and eventually the Tropic of Capricorn), the angle of the sun’s light hitting the atmosphere causes even more blue light to scatter, while red and green light decrease. That causes the sky to turn an even richer blue. These blue skies are especially easy to see in much of North America as cooler temperatures mean less moisture (and therefore fewer clouds), giving you an uninterrupted view of that deep azure atmosphere.

Here’s Why Surgical Scrubs Are Blue-Green

Medical professionals walking down a corridor together. — Credit: SolStock/ iStock

Walk into any hospital (or watch any medical drama), and surgeons are almost always wearing bluish-green scrubs. Because blue and green are far removed on the color spectrum compared to red, these cooler colors help refresh a surgeon’s eyes when operating on a patient (whose insides are essentially various shades of red). Because surgeons are visually focused on red-hued environments, glancing at a white background (the chosen hospital color of times past) can leave a ghostly green after-image, much like what your eyes experience after a camera flash. However, if the surrounding environment is green, then those after-images simply blend into the background.

In Elizabethan England, It Could Be Illegal To Wear Purple

Woman wearing an Elizabethan era gown. — Credit: Yuri_Arcurs/ iStock

From ancient times until as recently as the 19th century, the color purple was closely associated with royalty — often because they were the only class that could afford such luxury, which was extremely expensive to produce in the days when the color was still made from sea snails. Persian kings and Egyptian rulers wore the illustrious hue, and Julius Caesar similarly donned a purple toga, setting a 1,500-year-long trend for subsequent emperors in Rome and Byzantium.

The color was so intimately tied with the ruling class that the children of kings, queens, and emperors were said to be “born to the purple.” By the 16th century, however, things slowly began to change, as a wealthy merchant class began snatching purple-dyed garments of their own. In 1577, fearing that such lavish spending on “unnecessary foreign wares” could bankrupt the kingdom, Queen Elizabeth I passed sumptuary laws that essentially outlined a strict dress code based on class. Of course, the color purple (and crimson) was reserved for her majesty and her extended royal family, “upon payne to forfett the seid apparel.”

Scientists Recently Created the World’s Whitest Paint

Painting of walls in a white color. — Credit: 22 TREE HOUSE/ Shutterstock

In April 2021, scientists from Purdue University revealed a new shade of white paint. At first glance, it may look like any other plain white hue found at the local paint store. But unlike those other pigments, Purdue’s white paint reflects 98.1% of the sun’s rays. (Most white paints, by contrast, reflect only about 80% to 90%.)

According to Guinness World Records, that reflective ability makes the paint the whitest white that’s ever been created. And what Purdue’s hue lacks in chromatic sophistication, it more than makes up for in utility. According to The New York Times, if 1% to 2% of the world’s surface (about half the size of the Sahara) could be coated with this ultra-white paint, “the planet would no longer absorb more heat than it was emitting.” Although painting half the Sahara is not in the cards, painting the many, many rooftops that dot the world could help fight our current planetary fever while also cutting A/C costs. At midday, for example, the new paint makes surfaces 8 degrees Fahrenheit cooler than the surrounding ambient air temperature.

Hummingbirds Can See Colors That Humans Can’t

Rare hummingbirds from Costa Rica. — Credit: Vaclav Sebek/ Shutterstock

Colorblindness is relative. Just as we can perceive hues that dogs can’t, hummingbirds can see colors that humans can’t. Whereas the three types of color-sensitive cone cells in our eyes allow us to see red, green, and blue light, hummingbirds (and most other birds) have a fourth type of cone attuned to ultraviolet light. In addition to UV light, birds may even be able to see combination colors like ultraviolet+green and ultraviolet+red — something we mere humans can only imagine. Having four types of cones cells, known as tetrachromacy, is also common in fish and reptiles, and researchers believe that dinosaurs possessed it as well.

Being able to see this way is especially useful for hummingbirds, whose endless quest for sugar is aided by their ability to discern different-colored flowers — including “nonspectral” colors that combine hues from widely different parts of the color spectrum. Purple is the only nonspectral color we humans can perceive (it involves both blue and red, or both short and long wavelengths of light), but some birds might see as many as five: purple, ultraviolet+red, ultraviolet+green, ultraviolet+yellow, and ultraviolet+purple.

Bulls Can’t Actually See the Color Red

Spanish bull in spain. — Credit: alberto clemares exposito/ Shutterstock

If the very idea of bullfights makes you see red, you’re not alone — even though bulls themselves can’t actually see the color. As is the case with other cattle and grazing animals such as sheep and horses, bulls' eyes have two types of color receptor cells (as opposed to the three types that humans have) and are most attuned to yellows, greens, blues, and purples. This condition, a kind of colorblindness known as dichromatism, makes a bullfighter’s muleta (red cape) look yellowish-gray to the animals.

So why are bulls enraged by the sight of matadors waving their muletas? The answer is simple: motion. The muleta isn’t even brought out until the third and final stage of a bullfight. The reason it’s red is a little unsavory — it’s actually because the color masks bloodstains. In 2007, the TV show MythBusters even devoted a segment to the idea that bulls are angered by the color red, finding zero evidence that the charging animals care what color is being waved at them and ample evidence that sudden movements are what really aggravate the poor creatures.

Around 12% of People Dream in Black and White

Young Man Sleeping Cozily on a Bed. — Credit: Gorodenkoff/ Shutterstock

Whether they’re about showing up to school in your underwear or having your teeth fall out, most dreams have one thing in common: They’re in color. Not for everyone, though. Roughly 12% of people dream entirely in black and white, making their nightly visions much like watching an old movie. That comparison isn’t a coincidence, either. The number used to be much higher: In the 1940s, 75% of Americans reported seeing color in their dreams only rarely or never, and some researchers believe that black-and-white television is part of the reason why. Color TV didn’t become common until the 1950s and ’60s, so for many years, most people’s most common experiences with visual stories were in gray scale.

Giraffes Have Purple Tongues

Giraffe's head trying to reach a leaf with its tongue. — Credit: marseus/ Shutterstock

In addition to their spots and long necks, giraffes have another distinguishing feature: Their tongues are often dark purple. Whereas most animals have pink tongues, a giraffe’s is infused with melanin that makes it darker — sometimes it’s even blue or black rather than purple — although the base and back are pink. And while it hasn’t been proved definitively, the most widely accepted theory is that the melanin provides ultraviolet protection, preventing giraffe tongues from getting sunburned while the animals feed on tall trees. Giraffe tongues are also long (up to 21 inches) and covered in thick bumps known as papillae, which help protect them from the spiky defensive thorns of the animal’s favorite snack: acacia trees.

Giraffes aren’t the only creatures with darker tongues, of course; okapis, polar bears, impalas, and chow chow dogs have them as well, among other animals. However, giraffes are distinguished from their purple-tongued friends not only by their status as the world’s tallest mammal, but also because they give birth standing up. Newborn giraffes fall to the ground from a height of more than 5 feet, not that they mind — they can stand within half an hour and run within 10 hours, usually alongside their doting (and similarly dark-tongued) mother.