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RoughRoad
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Why do stars appear to be white in color when viewed from the naked eye?
http://www.aoa.org/x5352.xmlAccording to a widely held theory of vision, the rods are responsible for vision under very dim levels of illumination (scotopic vision) and the cones function at higher illumination levels (photopic vision). Photopic vision provides the capability for seeing color and resolving fine detail (20/20 of better), but it functions only in good illumination. Scotopic vision is of poorer quality; it is limited by reduced resolution ( 20/200 or less) and provides the ability to discriminate only between shades of black and white. This limitation can be easily confirmed by noting that, at dusk, the different colors of a flower garden become virtually indistinguishable. However, the scotopic system provides enhanced sensitivity and low detection thresholds under markedly reduced illumination.
Stars appear white because they emit a mixture of all visible light wavelengths, which our eyes perceive as white.
No, not all stars appear white. The color of a star depends on its temperature, with cooler stars appearing reddish and hotter stars appearing bluish.
Scientists use a tool called a spectrometer to analyze the light emitted by a star. This allows them to determine the wavelengths of light being emitted and thus the color of the star.
Yes, stars can change color as they age. As a star's temperature changes, so does its color. For example, a star may appear red in its later stages as it becomes cooler.
Stars twinkle because of the Earth's atmosphere. As light from a star passes through the atmosphere, it is refracted and scattered, causing the star to appear to twinkle or flicker. If viewed from space, stars would not appear to twinkle.