Electromagnetic Spectrum: The range of electromagnetic waves extending from radio waves to gamma rays.
Electromagnetic Wave: A wave that is partly electric and partly magnetic and carries energy. Emitted by vibrating electric charges.
Infrared: Electromagnetic waves of frequencies lower than the red of visible light.
Light year: The distance light travels through a vacuum during one year.
Polarization: The aligning of vibrations in a transverse wave, usually by filtering out waves of other directions.
Ray: A thin beam of light.
Ultraviolet: Electromagnetic waves of frequencies higher than those of violet light.