The Airy disk, named for the British astronomer Sir George B. Airy, is a small, disklike image produced by the diffraction of light when it passes through a telescope. Airy first calculated the size of the disk and found that it depended both on the wavelength of the light and on the diameter of the objective lens or mirror; the larger the aperture (diameter) of the objective, the smaller the Airy disk. A telescope with an aperture of 25 cm (10 in) produces an Airy disk that is 1 arc second in diameter for visible light.