Light Spectrum

The distribution of colours produced when white light is dispersed by a prism,
changing in wavelength from red (longest wavelength) to violet (shortest wavelength).
Seven colours are usually made out:
red, orange, yellow, green, blue, indigo and violet.


  • fastest thing in the Universe is light – travels at 186,282 miles per second!
  • light rays always travel in straight lines.
  • the light pass from one material to another, light rays change direction – its called refraction.



Wavelengths of Light

  • colours are different wavelengths of light.

  • longest light waves that can be seen are red, and the shortest are violet.
  • light is a form of electromagnetic radiation – light ray is a stream of tiny energy particles called photons.

Golden light ray or sun beam vector background. Abstract gold light flash spotlight backdrop with golden sunlight shine on black background

CCD Camera

  • faint light from very distant stars – often recorded by astronomy-camera sensors called CCDs  (Charge-coupled-devices – wikipedia); these count photons from the star as they arrive to build up a picture of the star at a long period.

Astronomy CCD Camera
(Atik 414ex)


Electromagnetic Spectrum

  • electromagnetic spectrum includes radio waves, ultraviolet light and X-Rays; visible light is the only part of the spectrum that can be seen by the human eye.
  • all light is given out by atoms – light can be viewed as small packets of energy (photons) -when hits an atom, energy is produced as light all light is given out by atoms.


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