This blog post examines the background and causes of scientific error that led scientists to long accept the non-existent canals of Mars as truth.
In 1894, claims that highly evolved intelligent life existed on Mars captured media attention. This claim was based on complex, intertwined lines appearing on maps of Mars at the time, referred to as canals. First reported in 1878, these Martian canals continued to appear on numerous maps for nearly 30 years. How could these non-existent Martian canals be accepted by astronomers for so long?
Many maps of Mars were produced in the late 19th century based on telescope observations. September 1877 was particularly significant because Earth was simultaneously close to both Mars and the Sun, making the Martian surface appear brighter than ever before. British amateur astronomer Nathaniel Everett Green traveled to the island of Madeira in Portugal, known for its clear atmosphere, and used a 13-inch reflecting telescope to sketch Mars directly as he observed it. Nathaniel Everett Green, who had extensive experience observing Mars, referenced his own previous observations and incorporated results from other astronomers to create the most sophisticated map of Mars available at the time.
However, the accuracy of Nathaniel Everett Green’s map was challenged the following year when Italian astronomer Giovanni Virginio Schiaparelli published his own map of Mars. Giovanni Virginio Schiaparelli’s map was based on observations conducted around the same time as Nathaniel Everett Green’s. This was because areas that appeared blurred on Nathaniel Everett Green’s map showed distinct terrain with intersecting lines forming a net-like pattern on Giovanni Virginio Schiaparelli’s map. Giovanni Virginio Schiaparelli called these features “canali,” a term that could be translated as straits or canals.
As Italian astronomer Giovanni Virginio Schiaparelli’s claims spread widely within academic circles, people became increasingly fascinated by the story of Martian canals. At the time, mass media and scientific journals reported on this extensively, and the idea of intelligent life existing on Mars captured the public’s imagination. Consequently, discussions about Mars became lively not only within the scientific community but also among the general public, with some people even beginning to seriously debate the possibility of communication with Martians.
Procedurally speaking, Nathaniel Everett Green held an advantage over Giovanni Virginio Schiaparelli. First, Giovanni Virginio Schiaparelli was a professional astronomer, but this was his first time observing Mars. Moreover, he conducted his observations from his own observatory, which had poorer atmospheric clarity than Madeira Island, and used an 8-inch reflecting telescope with relatively low magnification. Additionally, Schiaparelli sketched only the features in a short time and later refined them based on memory, creating his map based solely on his own observations.
Yet the victory went to Giovanni Virginio Schiaparelli. The decisive factor was that he was a widely known and respected astronomer within the astronomical community. Most astronomers found it difficult to believe that an astronomer they respected would have drawn terrain onto a map that was not even visible to the eye. Moreover, Giovanni Virginio Schiaparelli’s map, using the coloring techniques of geography, was more appealing than Nathaniel Everett Green’s map.
After Giovanni Virginio Schiaparelli reported several more observations of the canals, other astronomers began reporting their existence as well, and subsequently more canals appeared on maps of Mars. Schiaparelli’s canal theory influenced popular culture in various forms. Novels and plays published at the time sometimes depicted a highly advanced civilization on Mars, with an inevitable collision with Earth.
This atmosphere directly influenced the creation of H.G. Wells’ novel “The War of the Worlds.” This novel depicts Martians invading Earth, serving as a prime example of how scientific discoveries can stimulate the public imagination.
Furthermore, some scientists supporting the canal theory argued that this phenomenon could not be natural and was the result of Martian intervention. These claims gained further credibility by suggesting that the Martian canals were not mere topography, but potentially complex irrigation systems or transportation routes. Against this backdrop, Percival Lowell, a wealthy American businessman and astronomer, became convinced that intelligent life had constructed canals on Mars. In 1894, he established the renowned Lowell Observatory in Flagstaff, Arizona. At this observatory, Percival Lowell attempted to observe the Martian canals with greater precision, which brought the canal hypothesis even greater attention.
Once an authority announces they have discovered something, it is difficult to prove it does not exist. Moreover, in the prevailing climate where factors other than telescope performance were prioritized as measures of observational reliability, such errors were hard to correct. With larger, higher-performance telescopes, the canals were often not visible. Surprisingly, proponents of the canal hypothesis explained this by suggesting that large telescopes, due to their high magnification, could actually suffer from more severe atmospheric distortion under certain conditions, resulting in lower resolution than smaller telescopes.
Ultimately, as telescope technology advanced significantly and scientific understanding of Mars deepened in the early 20th century, the canal hypothesis gradually lost its influence. However, the observations of Giovanni Virginio Schiaparelli and his followers occupy an important place in the early history of Mars research, and it is undeniable that their work made significant contributions to the subsequent development of space exploration and planetary science.
