Every time you see a barn, it is probably red. Really, it's red because red paint is cheaper to make and cheaper to buy than all other paint colors.
Red paint is made from red ochre, Fe2O3, a simple combination of iron and oxygen which absorbs yellow, green, and blue light, and reflects red light (making you see red).
The only thing keeping living stars alive is the energy of their fusion reactions. Eventually, stars start to run out of fuel (hydrogen) and begin to shrink. As it shrinks the pressure inside the star goes up, as does the temperature. The temperature keeps rising until suddenly, it hits a temperature where a new reaction can get started.
This new reaction gives the star a big bust of energy, and it stops shrinking, and starts fusing again. This time however, it forms a heavier element (moving up one on the periodic table).
This cycle of shrinking and forming heavier and heavier elements repeats and repeats until it hits the 56 nucleon cutoff, iron. iron is strong enough and heavy enough to absorb everything the sun throws at it, and the sun simply can't do anything with it, so it can't produce more energy to stop gravity from collapsing it.
At this point, the sun shuts down and starts to collapse, 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.
Because the star stops at 56, it ends up making a lot of things with 56 nucleons. When the star breaks down completyl and explodes, it sends the iron it has left all across the universe. And there are a lot of dead stars, each with a lot of Iron.
So that means there is a lot of iron here on Earth.
Starting to see the connection?
Red paint is made from iron..... now you get it, good job.
And that is how the death of a star determines what color barns are painted.
