Sciency Words: Canali

Today’s post is part of a special series here on Planet Pailly called Sciency Words. Each week, we take a closer look at an interesting science or science-related term to help us expand our scientific vocabularies together. Today’s term is:


In last week’s episode of Sciency Words, we looked at one of the maps of Mars drawn by Italian astronomer Giovanni Schiaparelli, and we talked about how Schiaparelli invented many of the place names we still use for Martian geography today. But Schiaparelli’s work also led to one of the most embarrassing mistakes in the entire history of astronomy, and it all happened because of a word: canali.

Looking through his telescope, Schiaparelli saw (or thought he saw) little lines crisscrossing the Martian surface, and he labeled these lines “canali,” which is Italian for channel, but the word was mistranslated into English as “canals.”

It seems Schiaparelli believed these “channels on Mars” were a natural phenomenon, but that’s not the impression English-speaking astronomers got when they started reading about “canals on Mars.” And some astronomers, most notably American astronomer Percival Lowell, were so excited by the idea of Martian canals that they turned their own telescopes on Mars and saw (or thought they saw) exactly what they wanted to see.

This would be the same kind of technological geometrization that Carl Sagan would later write about in reference to Earth, but on a much larger scale. Except it’s not true. Mars is not covered in canals. Even before NASA started sending space probes to Mars, researchers found that the whole thing was probably a trick of the eye. To quote from a paper from 1903:

Our conclusion from the entire experiment is that the canals of Mars may in some cases be, as Mr. Green suggested, the boundaries of tones or shadings, but that in the majority of cases they are simply the integration by the eye of minute details too small to be separately and distinctly defined.

However, in more recent times our space probes have discovered other oddly geometric patterns on Mars, the kinds of patterns that may reveal a very different kind of Martian secret. But I’ll save that for next week!

2 thoughts on “Sciency Words: Canali

    1. Yeah, there is something delightful and magical about those canals on Mars. That’s probably why the idea has stuck around for so long, even after it was so thoroughly debunked by our space probes.


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