At some point in your life, you probably have pondered why your veins appear blue when your blood is red. Maybe you discovered the answer to this pressing question at some point in your life, or maybe to this day you still don’t know. If that’s the case, then you’re in luck, because we have the answer for you!
If you talk to a surgeon, they will tell you that your veins are actually red. This may confuse you because you clearly see your veins through your skin as being blue. So, what exactly is this trickery?
Although it’s not necessarily magic, there are different factors that come into play with this illusion. Some of the factors include how your eyes perceive color, how light behaves when it comes into contact with your body, and the special properties of blood.
Light travels through peaks and troughs, and a wavelength is the distance between each trough. Different colors have different size wavelengths, some longer or shorter than others. Red light is the longest wavelength and violet is the shortest.
We determine color when the light of the color reaches our eyes, which is either direct or a reflection.
But how does this affect the color of our veins? Well, light travels differently through different surfaces, skin included.
The light that hits our skin is mainly white, which is a mixture of all wavelengths. As mentioned, red has the longest wavelength, meaning it is less likely to be deflected by material and travels easily. Even through skin, the color red can pass through five to 10 mm below the skin, which is where many veins are located.
When red reaches the veins, it becomes absorbed by hemoglobin – the protein that makes blood red.
Unlike red, blue has much shorter wavelengths and is scattered and deflected far easier than red. Because it scatters so easily, it is not well absorbed by the skin and is mainly reflected back to the human eye.
If you shine a red light on your skin, you will see your veins quite clearly, but if you shine a blue light on your skin, you won’t see your veins and only blue skin. But when blue and red light are on your skin along with white light – the combination that occurs in daily life – that is when you see less red and bluer which is why your veins appear blue and not red.
This phenomenon varies greatly, though. For example, pale people veins appear bluer than someone with darker skin. Regardless, just know that the color that your veins appears doesn’t affect your health, but at least now you have a better understanding of it!