Did you ever wonder why white asparagus is white, or looks really pale from his friend green asparagus? I will then try to provide you with simple answer in here, however, let me start with the green asparagus.
Green asparagus, as any other green plant contains substance called chlorophyll. The pigment in the chlorophyll absorbs all other colors in spectrum and reflects the green light. Whenever the light is reflected, the human eye can see it. Same as for the red apple, or the orange carrot, the red and the orange colors are reflected and transmitted to our eyes.
A side note, a pigment is something that absorbs the certain colors in the light spectrum. Whatever is not absorbed is then reflected into our eyes.
So what happened to the poor white pale asparagus? Nothing really, it is grown in the dark and deprived from the sunlight. The blockage from the sunlight makes the asparagus white. No light to absorb or reflect. The process used to make the white asparagus is called process of etiolation, meaning that the plant is grown in partial light or completely without the light.