SPACE EXPLORATION
Why are most rockets white?
An Ariane 5 lifting off from French Guiana
In fact, there are two questions here: why are most rockets white? Conversely, why are some rockets not white? A white outer colour is useful to minimise heat absorption into the body of the rocket. For rockets that use fuels at very low cryogenic temperatures, such as liquid hydrogen and liquid oxygen, even very small amounts of heat introduction can result in the liquid fuel ‘boiling off’ into gas and being lost. Europe’s Ariane 5 rocket launches from French Guiana in South America, so reducing heat input to the rocket in that hot, tropical climate is important.
However, painting the surface of your rocket white adds weight to the rocket, which you want to be as light as possible, so you only do it when it brings real benefit. You can have rockets which are part white, part other colour, often the natural colour of the structure – orange for the thermal protection of the Space Shuttle fuel tank, for example. You can also decide not to paint the rocket at all – the Electron micro-launcher is allblack, the colour of the carbon fibre used in the structures.
Kate Underhill, rocket scientist at the European Space Agency
“A white outer colour is useful to minimise heat absorption into the body of the rocket”
The Sun turns orange or pink near the horizon
SOLAR SYSTEM