Name: Schiaparelli's Mars Canals
Author: Giovanni Virginio Schiaparelli

The plates accompanying Schiaparelli’s paper include some of the earliest detailed maps of the red planet, among them a large folding map of the planet’s surface and a separate representation of its southern hemisphere. It is within these maps that Schiaparelli’s most influential and controversial contribution emerges: the linear features he termed canali. Intended simply to denote ‘channels’ or ‘grooves’, the term was widely mistranslated into English as ‘canals’, with its implication of artificial construction.

The consequences of this mistranslation were far-reaching. The Martian canals ‘eventually became powerful cartographic icons that were viewed as indications of intelligent Martian life’.

Percival Lowell (1855–1916), though lacking formal astronomical training, established himself as a leading authority on the geography of 

 through a series of highly detailed maps. In these, the ‘canals’ became explicitly non-natural features: vast engineered structures, taken as proof of a dying but technologically advanced civilisation. While failing to convince the scientific community, Lowell’s confident interpretations – given persuasive authority through cartographic precision – captured the public imagination and helped to fix the idea of an inhabited 

 in popular culture. The idea of a canal-crossed 

 proved especially influential in early science fiction, most notably in the Barsoom novels of Edgar Rice Burroughs (1875–1950), where the planet is imagined as a dying world sustained by vast engineered waterways.

Schiaparelli’s maps of 

 offer a revealing example of the broader problem that underlies all cartography – the uneasy boundary between observation and imagination, and the question of how far maps can claim epistemological authority over the worlds they depict.

Ex Carta

In this influential study, the Italian astronomer Giovanni Virginio Schiaparelli presented some of the earliest detailed maps of the surface of Mars, based on his observations during the great opposition of 1877. His charts – identifying seas, continents, and the famous canali (later mistranslated as ‘canals’) – fuelled scientific speculation and helped inspire later visions of an inhabited Mars in science fiction.

In 1877, during an ‘unusually close approach of Mars to Earth’, the Italian astronomer Giovanni Virginio Schiaparelli (1835–1910) undertook a series of observations that would profoundly shape both scientific and popular conceptions of the planet (Nall, 2019). Using a powerful refracting telescope at the Brera Observatory in Milan, Schiaparelli produced the first systematic attempt to map the surface of Mars in detail, identifying and naming a network of light and dark regions that he interpreted, with caution, as analogues to terrestrial ‘seas’ and ‘continents’.

, this paper represents the first major presentation of his Martian studies. While Schiaparelli remained careful to stress the provisional and hypothetical nature of his interpretations, his work nevertheless marked a decisive moment in the transformation of Mars from a distant astronomical object into a world that could be described, classified, and – crucially – mapped.

Illustrations of Mars and its canals according to observations made with the equatorial telescope at Brera Observatory between Sept. 1877 and March 1878.  

Title page for the research paper by Royal Academy of the Lincei, 1878

Diagrammatical studies showing the of the direction of Mars's rotational axis

Four illustrations showing the visible appearance of the surface of Mars during the 1877 opposition, during studies on areographic longitude of the planet. 

An aerographic map showing the topography of the planet Mars between the South Pole and the 40th parallel of north latitude.

Stereographic map of the Southern polar hemisphere of Mars

The plates accompanying Schiaparelli’s paper include some of the earliest detailed maps of the red planet, among them a large folding map of the planet’s surface and a separate representation of its southern hemisphere. It is within these maps that Schiaparelli’s most influential and controversial contribution emerges: the linear features he termed 

. Intended simply to denote ‘channels’ or ‘grooves’, the term was widely mistranslated into English as ‘canals’, with its implication of artificial construction.

The consequences of this mistranslation were far-reaching. The Martian canals ‘eventually became powerful cartographic icons that were viewed as indications of intelligent Martian life’ (Lane, 2010). Percival Lowell (1855–1916), though lacking formal astronomical training, established himself as a leading authority on the geography of Mars through a series of highly detailed maps. In these, the ‘canals’ became explicitly non-natural features: vast engineered structures, taken as proof of a dying but technologically advanced civilisation. While failing to convince the scientific community, Lowell’s confident interpretations – given persuasive authority through cartographic precision – captured the public imagination and helped to fix the idea of an inhabited Mars in popular culture. The idea of a canal-crossed Mars proved especially influential in early science fiction, most notably in the Barsoom novels of Edgar Rice Burroughs (1875–1950), where the planet is imagined as a dying world sustained by vast engineered waterways.

Schiaparelli’s maps of Mars offer a revealing example of the broader problem that underlies all cartography – the uneasy boundary between observation and imagination, and the question of how far maps can claim epistemological authority over the worlds they depict.