The stars seen in the night sky have a variety of colors. There are red stars, shining blue in the constellation Orion, or yellow like the sun. Interestingly, none of the stars appear to have a purple or green tint.
Scientifically speaking, green and purple star colors are invisible because of the way humans perceive visible light. The color of the star that appears is closely related to its surface temperature
The hotter a star, the shorter the wavelengths of light it emits. The hottest colors are blue or blue-white with short wavelengths.
Conversely, if the surface temperature is cold, it tends to be red or brown with a longer wavelength of light, as reported by Live Science.
There is a range of light emitted by stars in one wave. This range is affected by surface temperature which can move the curve in one particular color, although it also emits other colors
The human eye has evolved to see yellow and green radiation which is probably because the sun emits radiation mainly at these wavelengths.
Green light stars shine right in the middle of the visible light spectrum. This means that the star also emits light of various colors. Therefore, the star appears white because of the combination of various colors.
This is also the reason why humans see the sun as white. Even though the sun has a lot of green light. But the color is not visible to humans.
Meanwhile, purple is also not easily visible because the human eye is more sensitive to blue.
Coupled with a star that emits purple light along with blue. This makes the purple color invisible compared to the prominent blue color.
(source: okezone.com)
