Aperture – the diameter of the primary mirror, or objective lens of a telescope

Diffract – the bending of light waves as they travel through openings

Frequency – the number of vibrations per second

Photon – a particle of electromagnetic radiation

Reflect – to bounce of the boundary between two mediums

Refract – when a wave bends as it passes from one medium to another

Spectroscope – a device that separates EMR into its component parts

Telescope – a device used to enlarge images of distant objects

Wavelength – the distance from one point on a wave to the same point on an adjacent wave

From Georgia Virtual Learning Astronomy