Red is the color at the end of the spectrum of visible light next to orange and opposite violet. Red color has a predominant light wavelength of roughly 620–740 nanometres. Red is one of the additive primary colors of visible light, along with green and blue, which in Red Green Blue (RGB) color systems are combined to create all the colors on a computer monitor or television screen. Red is also one of the subtractive primary colors, along with yellow and blue, of the RYB color space and traditional color wheel used by painters and artists. 

In nature, the red color of blood comes from hemoglobin, the iron-containing protein found in the red blood cells of all vertebrates. The red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide. It also causes the red color of the planet Mars. The red sky at sunset and sunrise is caused by an optical effect known as Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye. The color of autumn leaves is caused by pigments called anthocyanins, which are produced towards the end of summer, when the green chlorophyll is no longer produced. One to two percent of the human population has red hair; the color is produced by high levels of the reddish pigment pheomelanin (which also accounts for the red color of the lips) and relatively low levels of the dark pigment eumelanin.
What is red opposite to on the spectrum?
What is it next to?
what is the light's wavelength range?
What does RGB stand for?
What about RYB?
What does the red in blod come from?
What about in geological areas?
What causes the red sky at sunset?
Is it the same with sunrise?
What are the pigments affecting the leaves called?
Is it true that when the sun is low or below the horizon, the red-wavelength decreases the light that reaches the eye?
What percentage of humans are redheaded?
violet
opposite violet
orange
visible light next to orange
roughly 620–740 nanometres
wavelength of roughly 620–740 nanometres
Red Green Blue
Red Green Blue (RGB)
Red, Yellow, Blue
Red is also one of the subtractive primary colors, along with yellow and blue, of the RYB
hemoglobin
the red color of blood comes from hemoglobin
hematite or red ochre
The red color of the Grand Canyon and other geological features is caused by hematite or red ochre, both forms of iron oxide.
Rayleigh scattering
The red sky at sunset and sunrise is caused by an optical effect known as Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye.
yes
The red sky at sunset and sunrise is caused by an
anthocyanins
color of autumn leaves is caused by pigments called anthocyanins
no
Rayleigh scattering, which, when the sun is low or below the horizon, increases the red-wavelength light that reaches the eye. 
two
two percent of the human population has red hair