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Smoke signals have been used by people for thousands of years to communicate various messages. It can be difficult to control smoke, so the type of communication has to be at least somewhat simple, but due to the nature of smoke, it can be seen from great distances away, which makes it very effective.
While almost everyone is aware that smoke signals exist, most people will never use them on their own. Just about everyone, however, has seen at least one use of a smoke signal very recently. The most famous use of this type of communication was seen by billions of people around the world on May 8th, 2025.
What is it? Smoke coming out of the chimney above the Sistine Chapel at the Vatican, of course.
When the Catholic Church needs to elect a new Pope, all of the cardinals come together at the Sistine Chapel and get locked together to vote for the successor of St. Peter. While just about any male Catholic can technically be elevated to Pope, one of the Cardinals who are in the chapel will virtually always be chosen.
In order to be elected as Pope, the individual must receive 2/3 of the votes (there are some additional details, but for this article, getting 2/3’s is accurate enough).
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This whole process is known as a conclave, and when it happens, the Cardinals will hold four votes per day until someone is elected. If nobody is elected on the first vote, the small pieces of paper each Cardinal uses to vote are gathered together and set aside. If again nobody is elected on the second vote, all of those papers are gathered together and burned along with three chemicals: Potassium perchlorate, anthracene, and sulfur.
This combination creates a black smoke, which rises out of the chimney in the chapel, signaling to the outside world that no new Pope has been elected.
Once a Pope is elected, the ballots are gathered together and burned with three different chemicals: Potassium chlorate, lactose, and rosin. This creates a white smoke, signaling that a new Pope has been elected.
With over 1.6 billion Catholics around the world, and billions more interested in who the Pope might be, this is by far the most widely seen smoke signal in the world.
To see how the smoke is made, check out this video:
In the video, you will see someone (not a Cardinal) combining the chemicals and burning them to give off the distinctive smoke.
Using smoke to announce the new Pope may seem like something that has always been done, but it only started to be the practice in the 1800s. At that time, the ballots were only burned if no Pope had been elected, so any smoke meant no new Pope.
It was only when Pope Benedict XV was elected in 1914 that the chemicals were added to indicate whether he had been elected.
If you thought that was interesting, you might like to read about the mysterious “pyramids” discovered in Antarctica. What are they?