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.
Speed of light: The speed of light in vacuum, commonly denoted c, is a universal physical constant important in many areas of physics. Its value is exactly 299,792,458 meter per second, a figure that is exact because the length of the meter is defined from this constant and the international standard.