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How did a reflecting telescope reduce chromatic aberration?

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Isaac Newton Isaac Newton, oil on canvas by Sir Godfrey Kneller, 1702; in the National Portrait Gallery, London. Newton's discoveries in physics and mathematics revolutionized science.

A reflecting telescope reduces chromatic aberration because it uses mirrors rather than lenses to focus light.12

In a refracting telescope, chromatic aberration occurs because glass lenses refract light differently depending on its wavelength, causing different colors to focus at slightly different points. Because the refractive index of glass varies with color, a single lens cannot bring all wavelengths of light to the same focal point, resulting in image distortion.32

Isaac Newton invented the reflecting telescope to overcome this limitation. Because reflected light does not disperse according to wavelength, the primary mirror of a reflector does not suffer from the color-dependent focusing issues inherent in glass lenses. By utilizing reflection to gather and focus light, the instrument avoids the dispersion that creates chromatic distortion, providing a clearer image.214