Why Do Veins Look Blue or Green?
There are three types of veins:
- Deep veins
- Pulmonary veins
- Superficial veins
Amongst the three, superficial veins are the type that you can see, that may appear to be blue or green. The reason they look green instead of red is because the color green has a shorter wavelength than the color red. This is also the same reason they may appear blue or bluish-green because blue also has a shorter wavelength than red.
The electromagnetic spectrum contains wavelengths, or visible light that your eye can see. The color of visible light ranges from red to violet, in this order: red, orange, yellow, green, blue, violet. Red has the longest wavelength, lowest frequency, and least amount of energy. This explains why you see the vein as green or blue instead of red.
What we perceive as “color” is actually the frequencies of the visual light spectrum that are reflected from a surface while other waves are absorbed. For instance, a green leaf reflects the green waves and absorbs the other colors, which is why we see it as green.
The illusion of “green” or “blue” veins occurs because you’re viewing them through layers of skin and tissue, which absorb more of the red frequencies while allowing higher frequency waves to reach your eyes.