Like Venus, Mars has long been an object of fascination to men – the red wanderer among the heavens, historically associated with the God of war, whose retrograde motions baffled astronomers for centuries. More than any other planet, Mars has experienced oscillating periods of interest; it has dominated astronomical studies as an irregularity and a world teeming with intelligent life, and falling into disinterst as a cold world. The trend has continued in the modern era of space exploration, with rovers and orbital spacecraft returning periodically to the red planet to explore the latest point of interest. (Pictured: Mars.)
Before this modern technological era, Mars enjoyed great popularity in the Victorian era as a life-harbouring planet. Emerging technologies applied to Martian studies combined with wildly fantastical theories to paint Mars as a probable second Earth – long before proposals of terraforming and colonization.
The idea of life on other planets, commonly referred to as the argument for a plurality of worlds in the Victorian era, has its roots in the Copernican revolution. With the Earth stripped of its privileged centrality, it was hard for men of science to imagine that God would give the gift of life to this random planet and no others or leave his only life in an unprivileged position. This was, after all, the era of the book of nature – God’s presence and design was everywhere, including the solar system.
Astronomer William Whewell (left), best known for his fierce denial of a plurality of worlds, was actually one of the first to promote the idea of life on other planets – every planet, as a matter of fact. Plurality was just so tempting; he couldn’t resist expanding the majesty of life to every solar body. Twenty years later in the middle of the 19th century, he changed his tune with the discovery of fossils. Fossils, he thought, were a clear indication of wasted life on Earth. The Divine worked out many designs before settling on humans, and He certainly wouldn’t fill the universe with more waste. Maybe humans were the special ones, perfected in God’s image, and alone as the perfect life form. A pretty flattering reason to argue that life only existed on our planet.
Whewell’s change of heart offended fellow astronomers, particularly his previousintellectual sparring partner Scottish astronomer Sir David Brewster (right). Brewster countered Whewell by arguing that every planet harboured it’s own Divinely-created life. In spite of their conflicting opinions, both astronomers recognized that Mars was likely to harbour life.
The similarities between Earth and Mars were too striking to ignore. Both planets are of a similar size. Both have similar daily rotations; Earth’s daily rotation takes 24 hours while Mars’ takes 25 hours. Even the observed surface characters on Mars were comparable to those on Earth: continents, oceans, green areas, snow at the polar regions, and an appreciable change in surface features as one sees with the Earthly seasons.
In comparison to these similarities, the differences between the planets were negligible. Observed differences could be explained away by the nebular hypothesis – the theory that bodies further from the sun are cooler. Mars, then, is an older and cooler body than Earth and further along in its planetary development. Its appearance is indicative of its different geological era.
Physical differences, such as Mars’ weaker gravitational pull and its greater distance from the Sun, would just change the way life on Mars looked – Brewster allowed for each planet’s individual characteristics to ‘design’ its inhabitants, a pretty reasonable conclusion. After all, Earth has loads of differently-shaped life forms in different environments. It only makes sense that Martian environments are analogous to extreme Earthly environments.
French astronomer Camille Flammarion (left) joined the ‘plurality of worlds’ bandwagon in the latter half of the 19th century with the same argument – it only made sense that life in different environment would be take on different forms. Flammarion’s Martians weren’t humanoid at all, but he was certain there was life on Mars.
Next to join the ‘Martian life’ party was Richard Anthony Proctor (below, right), best known as the founder of Nature. Proctor’s astronomy, which relied heavily on observation of surface features, had extraterrestrial life at its core. He, like Brewster and Flammarion, determined that the white polar regions were snow. Drawing analogies with Earth, he was certain the snow accumulated in the winter and melted in the summer, bringing about a lovely spring season, perfect for vegetation growth, which is in turn great for life on Mars.
Mars was looking like a lovely place in the end of the 19th century, but the game changed in the early 20th century. Telescopic observations, which to this point had dominated planetary observations, were overtaken by the new science of spectroscopy – determining a celestial object’s chemical composition by analysing the absorption pattern of is light spectra. The two methods combined to further knowledge of Martian life: telescopes revealed surface features while spectroscopy revealed of what those surface features were made.
In the case of Mars, finding spectroscopic evidence of water vapour was the ultimate prize. Light passing through water vapour has a known interference pattern on a light spectrum, so a comparison of light from Mars against this control would indicate the presence of water on Mars.
The first promising aqueous evidence came from another Mars-enthusiast, William Huggins (left). Huggins compared spectroscopic results of light reflected from both Mars and the Moon. Because the Moon has no atmosphere, it served as a control. Any indication of water vapour from the Moon could be dismissed as part of Earth’s own atmosphere. If, however, the light from the Moon was without interference, any indication of water from the light on Mars would be unquestionable evidence of water on the planets surface.
Proctor published Huggins’ findings in Nature that determined with certainty the existence of water on Mars. This only fuelled Proctor’s fire. He took this as incontrovertible evidence that he was right: the polar caps melt with seasonal changes, sending water cascading across the surface, in turn regulating the climate. Mars, he proclaimed, was a mini Earth. Complete with a wondrous variety of life forms.
Proctor found support from Italian astronomer Giovanni Schiaparelli (right) who visually confirmed the existence of water on Mars. Schiaparelli observed not only accumulation and subsequent melting of the polar caps, he saw evidence of the movement of the water across the planet’s surface. He observed around the melting ice caps a dark area he took to be a ‘sea’. Not long afterwards, he noticed dark lines extending from this ‘sea’ reaching down into the continents on Mars.
He called these lines cannali, the Italian term for natural surface features similar to channels on Earth. These were, he surmised, the planets natural irrigation system that promoted the spread of liquid water around the planet supporting life across the entire surface. He proposed that the water would move continually over the surface, first away from the poles via the cannali then return to the poles as vapour in the atmosphere, falling on the poles as snow in another winter. The natural surface feature gave the planet a natural cycle of life. Mars was beginning to have a knowable geography, properly called areography.
But not everyone was quick to take Schiaparelli’s findings as exciting news. There were detractors who explained the dark areas that made the so-called cannali as simply shadows cast by an unknown Martian landscape. The same was the dark areas on the Moon were once considered seas; the Martian landscape was playing tricks its on human observers.
Others, however, latched on to the cannali. Proctor used the cannali’s apparent size and the natural cycle they induced on the planet to speculate about the physical characteristics of Martian inhabitants. Perhaps the most famous supporter of the cannali was American astronomer Percival Lowell (left), for whom the Lowell observatory in Flagstaff, Arizona is named.
Lowell’s studies of Mars began with observations of the polar caps, but quickly expanded to include any and all observed surface features. Schiaparelli’s cannali particularly grabbed Lowell’s imagination, though in a slightly modified form. Lowell mistranslated cannali. He took the meaning not as natural channels but as canals, man made structures like the Panama Canal. Canals are exceedingly complex, the construction of which is an impressive feat of engineering. Because the canals on Mars could be seen from Earth, Lowell determined that they must be absolutely titanic. Not only that, but such a massive undertaking could only be the result of a highly coordinated effort. Martians were not only an advanced life form; they were really clever!
Lowell took his observations a step further, inferring a history of the unseen and unknown Martians. The canals were an obvious means of spreading the water from the poles around the planet, a necessary step only if the planets natural resources were depleted. The canals were, he guessed, the last efforts of the Martians to save their race. This, coupled with the lack of obvious signs from the highly intelligent canal building Martians, led Lowell to conclude that the planet, once inhabited, had died.
Bigger and more powerful telescopes killed the Martian canals the way drought had killed Martian inhabitants – further observations revealed that neither really existed. After the first quarter of the 20th century, interest in Mars waned as evidence of life was systematically disproven. Not until the space age began did Mars enjoy a resurgence of attention. Parallel to its manned program, NASA has devoted substantial energy to the exploration of the red planet. The orbital probes and rovers sent to unlock its secrets have begun a new phase of Martian fascination – the red celestial wanderer still retains its hold over men.
Percival Lowell. Mars and its Canals. Available on Google Books.
Richard Anthony Proctor. Other Worlds than Ours. Available on Google Books.
Sir David Brewster. More Worlds than One. Available on Google Books.
William Whewell. Of the Plurality of Worlds. Available on Google Books.
Richard Corfield. Lives of the Planets. Basic Books, 2007.