Let’s learn about colors

We live in a colorful world. Green leaves spring from the trees, flowers come in every color of the rainbow, and birds sport fashionably colorful feathers. We even live on a pale blue dot.

What creates all this color? Electromagnetic radiation — waves of energy moving through space. The waves come in different lengths. Cells in the backs of our eyes can perceive light as black, white, red, green or blue. The cells then relay that information to the brain — and we see the world in color. But we don’t see every color. Many wavelengths are beyond what humans can see.Nature has come up with many ways to make colors. Leaves, for instance, get their green from chlorophyll — the same chemical that helps them make sugar from sunlight. Some beetles, though, are beautifully shimmery from tiny structures in their wings. Those structures bounce light off differently at each angle, producing iridescence. And peacock spiders use a combination of pigments and tiny structures to get their beautiful behinds.

Power words

angle: The space (usually measured in degrees) between two intersecting lines or surfaces at or close to the point where they meet.

beetle: An order of insects known as Coleoptera, containing at least 350,000 different species. Adults tend to have hard and/or horn-like “forewings” which covers the wings used for flight.

birds: Warm-blooded animals with wings that first showed up during the time of the dinosaurs. Birds are jacketed in feathers and produce young from the eggs they deposit in some sort of nest. Most birds fly, but throughout history there have been the occasional species that don’t.

cell: The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells. Most organisms, such as yeasts, molds, bacteria and some algae, are composed of only one cell.

chemical: A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.

chlorophyll: Any of several green pigments found in plants that perform photosynthesis — creating sugars (foods) from carbon dioxide and water.

electromagnetic: An adjective referring to light radiation, to magnetism or to both.

electromagnetic radiation: Energy that travels as a wave, including forms of light. Electromagnetic radiation is typically classified by its wavelength. The spectrum of electromagnetic radiation ranges from radio waves to gamma rays. It also includes microwaves and visible light.

hue: A color or shade of some color.

iridescent: Adjective that describes something that seems to change color with a shift in the angle at which it is viewed or at which lighting is applied.

pigment: A material, like the natural colorings in skin, that alter the light reflected off of an object or transmitted through it. The overall color of a pigment typically depends on which wavelengths of visible light it absorbs and which ones it reflects. For example, a red pigment tends to reflect red wavelengths of light very well and typically absorbs other colors. Pigment also is the term for chemicals that manufacturers use to tint paint.

radiant: (adj.) A term for something that is radiated, such as heat or some other type of radiation. (n.) The point or object from which light or heat radiates (such as the heating element in an electric heater). Or the point from which objects (such as meteors) appear to come.

radiation: (in physics) One of the three major ways that energy is transferred. (The other two are conduction and convection.) In radiation, electromagnetic waves carry energy from one place to another. Unlike conduction and convection, which need material to help transfer the energy, radiation can transfer energy across empty space.

robot: A machine that can sense its environment, process information and respond with specific actions. Some robots can act without any human input, while others are guided by a human.

spider: A type of arthropod with four pairs of legs that usually spin threads of silk that they can use to create webs or other structures.

wave: A disturbance or variation that travels through space and matter in a regular, oscillating fashion.

wavelength: The distance between one peak and the next in a series of waves, or the distance between one trough and the next. It’s also one of the “yardsticks” used to measure radiation. Visible light — which, like all electromagnetic radiation, travels in waves — includes wavelengths between about 380 nanometers (violet) and about 740 nanometers (red). Radiation with wavelengths shorter than visible light includes gamma rays, X-rays and ultraviolet light. Longer-wavelength radiation includes infrared light, microwaves and radio waves.