Question

Why does the blood in your veins just under your skin look blue?

Answer 1

They appear blue because blue light is reflected back at our eyes. Blue does not penetrate human tissue as well as red light does. Therfore if the vein is closer to the surface, it will most likely appear blue

Explanation; :Blue does not penetrate human tissue as well as red light does. Therefore if the vein is closer to the surface, it will most likely appear blue

Answer 2

As blood travels through your body, it loses the oxygen and takes on carbon dioxide (which you exhale). This oxygen-low blood is a darker shade of red.

The veins themselves are not blue, but are mostly colorless. It is the blood in the veins that gives them color. Furthermore, the blood in human veins is also not blue. Blood is always red. Skin scatters a lot of the red portion of white light before it can reflect off the blood, leaving the blue light to reflect off the blood and back to our eyes. (Baird 1)

In short, our veins appear blue because of a trick that light plays on our eyes and how the light interacts with our body and skin.