"Yet if hope has flown away
In a night, or in a day,
In a vision, or in none,
Is it therefore the less gone?
All that we see or seem
Is but a dream within a dream."
"A Dream Within a Dream" (1849) by Edgar Allan Poe
Mars - a distant, extraterrestrial world, but it shares some surprising similarities with Earth. The rotation period is almost the same with 24 hours, 39 minutes and 21,67 seconds (as measured by astronomer William Herschel in 1777-1783), the planet possess an atmosphere and the surface shows periodic changes during a sequence of seasons.
First drawings of the Martian surface appeared in 1638, made by the Italian astronomer Francesco Fontana, and in 1645 the Dutch astronomer Christiaan Huygens produced the first "scientifically accurate" map, showing, so he believed, the large "hour glass"-ocean (today known as Syrtis Major, the southern highlands of Mars). In 1672 the Italian astronomer Giovanni Domenico Cassini (1625-1712) noted on the South Pole a white patch and in 1704/1719 a nephew of Cassini, Giacomo Filippo Maraldi (1665-1729), discovered also on the North Pole such a patch. It was William Herschel who suggested that these were polar ice caps and the extent of the glaciers varied during the Martian seasons. The melting polar ice caps suggested also that there was liquid water on Mars.
Fig.1. One of the first widely published maps of Mars, from Proctor (1876) "Other Worlds than Ours" (image in public domain).
In the 19th century improved telescopes made even more accurate maps possible. The French astronomer Camille Flammarion (1842-1925) analysed more than 2.600 drawings of Mars and published in 1876 a very detailed map, showing already two large oceans, 22 lakes, four sea channels and five continents. According to Flammarion, Earth and Mars were so similar, that a visitor would not notice substantial differences:
"Rivers, glittering golden in their riverbed made of pebbles, creeks flowing through the plains or disappearing with waterfalls into valleys, large streams flowing slowly through the landscape to disappear into the sea."
Fig.2. A map of Mars from Flammarion (1881) "Les Terres du Ciel" (image in public domain).
But by far the most famous description from Mars came from the Italian Astronomer Giovanni Schiaparelli Virgino (1835-1910). Schiaparelli was interested in binary star systems, but after the description by the Italian astronomer Father Angelo Secchi of strange regular structures on Mars, he decided to try if his new telescope (one of the first in the new founded Italian Kingdom) could also be used to study the surface of other planets.
He named the structures "canali", an ambiguous term that can refer to artificial "canals" but is more appropriate for natural "streambeds and channels". In fact Schiaparelli described the canali simply as depressions, through which water can flow from the ice caps to the equatorial oceans. He states
"It is not necessary to assume that it was the work of intelligent beings, and in spite of the geometric appearance of the whole system, we are inclined to believe that it originated during the evolution of the planet, just as on Earth the English Channel or the Channel of Mozambique."
Schiaparelli was one the first astronomers to note that the canali changed shape, size and even number during a Martian year. He suspected that this was caused by periodic flooding events on the planet, when the glaciers on the poles melted during a Martian spring.
Despite his first conservative descriptions of the surface of Mars, Schiaparelli didn't dismiss the possibility that Mars was habitable (or even inhabited) - a very popular idea at the time. In 1895 he published an article - "Life on Mars"- in which he speculated about this possibility. The apparent changes of the system of canals observed since 1882 could be the results of an intricate irrigation system, used by Martian to irrigate the dry equatorial regions. He even tried to describe the social structure of the Martian civilization, arguing that such gigantic constructions needed a strong central government to be build and monitored, so he assumed that Mars was ruled by a socialist and peaceful community
The idea of not only an inhabited, but civilized planet Mars, became very popular with the work of the American Percival Lowell (1855-1916). A colleague and friend of Lowell - William Henry Pickering - stated correctly that the dark areas observed for centuries on Mars could not be oceans, because they lack reflections as expected on waves of water. Pickering expressed the opinion that this was some kind of vegetation covering the Martian hills. The observed periodic changes suggested that this vegetation vanished during drought periods, exposing the brighter Martian surface. Lowell fitted these speculations in his own view on Mars - the Martians were trying to lengthen the growing season by building more and more canals, to distribute the precious water over the entire planet.
"The drying up of the planet is certain to proceed until its surface can support no life at all. Slowly but surely time will snuff it out. When the last ember is thus extinguished, the planet will roll a dead world through space, its evolutionary career forever ended."
The supposed existence of intelligent Martians inspired also the first science-fiction writers. In 1865 the book "Un habitant de la plante Mars" (An inhabitant of the planet Mars) by French author Henri de Parville (1838-1909; and a friend of Flammarion) reported the discovery of a Martian Mummy, found during drilling operations in the U.S. and conserved in a buried meteorite*:
"some parts seemed carbonized and the short legs were damaged during the extraction, the head was intact, no hair, instead a smooth, coriaceous skin, a triangular-shaped brain,..…instead of a nose a short trunk, a small mouth with some teeth, two orbital cavities with the eyeballs removed in the past, as limestone had formed in there…"
De Parvilles fictive account, based on the most recent speculations on the environments found on Mars, was so compelling that Flammarion used the depiction of the Martian in his book "Les terres du ciel" (1884), where he discussed life in our solar system.
"The biological conditions on Mars are very similar to Earth, there are mountains, oceans, continents and polar caps. Therefore it can be assumed that there are also beings, very similar to us humans, to be found."
de Parville 1865
All this was based on observations that were made from Earth - even if the best telescopes could provide only blurred images of Mars. Written arguments against the inhabited Mars, like provided by naturalist Alfred Russel Wallace, who argued that it was too cold on Mars for liquid water, had a hard time keeping up with the intriguing and mysterious maps showing an earth-like Mars.
*It's curious to note that de Parville imagined that the Martian mummy arrived to Earth when a meteorite struck Mars and catapulted a part of its surface into space. In 1996 NASA announced the discovery of structures in the Martian meteorite ALH 84001 of supposed biological origin.
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