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Gallery 3

Blue Sky

Photo of Blue Sky exhibit

Colours aren't always as they appear.

How it works

Observe the way the colour scatters.Turn off different colours to see how each is affected differently.

Things to try or ask around the exhibit

  • Is the light the same colour at the beginning as it is at the end?
  • What colour is the light in the middle?

Background

There are several ways colours appear to us. Usually the colours we see are light waves bouncing off objects. Any light wavelengths absorbed by the object can’t be seen. However when light from the Sun travels through the atmosphere, it passes through kilometres of gas in Earth's atmosphere.
When light hits particles much smaller than its wavelength, it gets scattered. The more it travels through the atmosphere the more light becomes scattered. This is called Rayleigh scattering. When you look up at the sky, it appears blue because these wavelengths were scattered out from the sunlight. Light directly from the Sun appears yellow and orange, as these wavelengths aren’t scattered out.

Finding the science in your world

Rayleigh scattering doesn't just occur in the atmosphere. The blue eye colour in humans is a result of the same effect. Humans only possess brown/red pigments, so for our eyes to appear blue the wavelength scatters off the small amount of brown pigments in the iris.