The first astronomer to classify stars according to their color was F. They serve two key roles in plants and algae: they absorb light energy for use in photosynthesis, and they protect the green chlorophyll from photodamage.
In late summer, as daylight hours shorten and temperatures cool, the veins that carry fluids into and out of the leaf are gradually closed off.
Yellow is the color between green and orange on the spectrum of visible light.
It is evoked by light with a dominant wavelength of roughly 570–590 nm.
In the 20th century, Jews in Nazi-occupied Europe were forced to wear a yellow star.
In the nineteenth century, the scientists Grassmann and Helmholtz did experiments in which they concluded that finding a good complement for spectral yellow was difficult, but that the result was indigo, that is, a wavelength that today's color scientists would call violet or purple.
The green lines show several possible pairs of complementary colors with respect to different blackbody color temperature neutrals, illustrated by the "Planckian locus".
That is, when two colored lights can be mixed to match a specified white (achromatic, non-colored) light, the colors of those two lights are complementary.
In color printing, yellow is one of the three colors of ink, along with magenta and cyan, which, along with black, can be overlaid in the right combination, along with black, to print any full color image. A particular yellow is used, called Process yellow (also known as "pigment yellow", "printer's yellow", and "canary yellow") subtractive primary colors, along with magenta and cyan.
Process yellow is not an RGB color, and there is no fixed conversion from CMYK primaries to RGB.