Question: Why do some objects have colourful shadows and others not? For example:balloons

Reka Nagy answered on 17 Nov 2016:

Balloons are see-through, so they don’t reflect all the light that hits them, unlike other materials such as walls, which reflect all the sun. The shadows of walls are therefore black because there is no actual light there.

Light is made up of all colours, and each colour has a different wavelength. The reason we see colour in the first place is because object absorb some wavelengths and reflect others – and the ones they reflect are the ones we perceive as their colour – so it is a bit mind-boggling that the colour we see things as is actually the only colour they are NOT!

Balloons, as I said, let some of the light through. They are themselves coloured, so they absorb some of the wavelengths of light, letting the rest through and forming a colourful shadow!