Close your eyes and picture a barn.
What color was it? Red, right?
For as long as I can remember, barns have been red. I mean, sure, there are some randomly colored barns out there, but most are red. I never put much thought into the reason that they’re all so similarly-painted, and now I don’t have to.
We have an answer. According to Smithsonian.com:
The compound that makes red paint is very cheap and very plentiful thanks to dying stars. Wait, what?
That wasn’t a typo. Dying stars play a vital role in red paint. Get ready for a little science, so put your thinking caps on:
The only thing holding the star up was the energy of the fusion reactions, so as power levels go down, the star starts to shrink. And as it shrinks, the pressure goes up, and the temperature goes up, until suddenly it hits a temperature where a new reaction can get started. These new reactions give it a big burst of energy, but start to form heavier elements still, and so the cycle gradually repeats, with the star reacting further and further up the periodic table, producing more and more heavy elements as it goes. Until it hits 56. At that point, the reactions simply stop producing energy at all; the star shuts down and collapses without stopping.
As soon as the star hits the 56 nucleon (total number of protons and neutrons in the nucleus) cutoff, it falls apart. It doesn’t make anything heavier than 56. What does this have to do with red paint? Because the star stops at 56, it winds up making a ton of things with 56 neucleons. It makes more 56 nucleon containing things than anything else (aside from the super light stuff in the star that is too light to fuse).
The element that has 56 protons and neutrons in its nucleus in its stable state? Iron. The stuff that makes red paint.