An Airy disk is a pattern of light that appears when a point source, like a distant star, is viewed through a circular aperture, such as a telescope lens. This phenomenon occurs due to the diffraction of light, which causes the light waves to spread out and create a central bright spot surrounded by concentric rings of decreasing intensity. The size of the Airy disk is determined by the wavelength of light and the diameter of the aperture. A larger aperture results in a smaller Airy disk, allowing for better resolution in imaging. This concept is crucial in optics and astronomy, influencing how we observe celestial objects.