Barns are painted red because of the physics of dying stars Fall colors frame a red barn in East Montpelier, Vt. (AP Photo/Toby Talbot/AP Photo/Michael Felberbaum)
Barns are painted red because of the physics of dying stars
Lexile

Have you ever noticed that almost every barn you have ever seen is red? There's a serious reason for that, and it has to do with the chemistry of dying stars.
 
Yonatan Zunger is a Google employee who explained this phenomenon on Google+. The simple answer to why barns are painted red is because red paint is cheap. The cheapest paint there is, in fact, but the reason it's so cheap is the interesting part.
 
Red ochre - Fe2O3 - is a simple compound of iron and oxygen that absorbs yellow, green and blue light and appears red. It's what makes red paint red and it's really cheap because it's really plentiful. And it's really plentiful because of nuclear fusion in dying stars.
 
Zunger explains:
 
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 (the total number of protons and neutrons in the nucleus) cutoff, it falls apart, and 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 nucleons. It makes more 56 nucleons 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 is iron, the stuff that makes red paint.
 
And that, Zunger explains, is how the death of a star determines what color barns are painted.

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CRITICAL THINKING QUESTION
Why would farmers choose the least expensive paint for their barns?
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COMMENTS (6)
  • monicas-ste
    4/20/2017 - 01:04 p.m.

    This is really cool. I never knew this. At least they're saving money by using cheap paint.

  • vaneises-
    4/24/2017 - 08:34 a.m.

    Farmers would choose the cheapest color to paint their barns because barns are rather large and it would only be logical to cover the barn in the least expensive color.

  • cheyannec-kut
    4/29/2017 - 11:14 a.m.

    I never took the time to think about why barns were red before reading this. I was surprised that red colored paint is created from dying stars. I think that they use the least expensive paint because the barn isn't supposed to be for looks. The cheaper the price, and the faster you put it up, the better.

  • DLee17
    5/03/2017 - 11:47 a.m.

    this is some sid the science kid stuff!

  • kaileew-ste
    5/04/2017 - 01:29 p.m.

    When I think of a barn, I think of the color red. I never knew there was a reason for this. I think this is really interesting.

  • juliac-kut
    5/14/2017 - 09:02 p.m.

    I never thought much about the fact that all barns were red, I just figured it was traditional. I had to read this twice because of my amazement. I was confused, but interested. This definetely changed my thoughts on farms.

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