Saturn

Atmospheric Dispersion Corrector - The ability to produce good quality high-resolution planetary images is hampered by atmospheric dispersion, an effect in which white light is separated vertically into a spectrum of colors, with blue at the top and red at the bottom. The atmosphere effectively acts like a weak prism, causing light entering at an angle to be bent by refraction to a slightly steeper angle. Because refraction is wavelength dependent, an effect known as dispersion, the apparent ''lift'' that the object gets from atmospheric refraction varies according to the color of the light (see figure 1 below). Atmospheric dispersion gets more pronounced when the altitude of the object is lower.