Are the channels on Mars real?

By mid-1900s the Martian-canal confusion had cleared completely, and scientists were convinced that Mars was a dry planet. Photographs taken by the U.S. National Aeronautics and Space Administration’s (NASA) Mariner 4 spacecraft in 1965 and other Mars missions after that had played a huge role in it. That was why everyone was puzzled when about a decade later, in 1972; NASA’s Mariner 9 sent back images of a Martian surface lined with grooves! These were no Martian-made canals like Lowell had predicted, or straight, crisscrossing canali like the ones Schiaparelli had sketched on his maps. They were winding channels carved into the surface of Mars, kilometres long, and very similar to the river-made features we see on the Earth, except that they were completely dry!

It clearly looked as if flowing water had created such terrains but Mars had no liquid water! In fact, its atmosphere is so thin and dry that any water poured on its surface will immediately freeze or evaporate. Gradually, as more and more evidence of its past was discovered, scientists understood that Mars might have been quite a different planet millions of years ago - with a denser atmosphere, it might have been warmer and wetter than it is today. This justifies the possibility that the Martian channels may have been created by floods!

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What was the best thing that came out of Lowell’s obsession over Martian canals?

During the years he spent studying Mars and its “system of canals,” the American astronomer, Percival Lowell, popularized the idea of the presence of intelligent life on Mars through newspapers and his books Mars (1895), Mars and its Canals (1906), and Mars as the Abode of Life (1908). Even though his theories were ultimately proven false, Lowell made great contributions to the field of astronomy. The Lowell Observatory he established in Arizona, U.S.A, in 1894 is one among them.

Using the 24-inch refracting telescope installed in his observatory, Lowell observed not only Mars but also Venus. In the later years of his career, he focused his energies on finding Planet X, the imaginary tenth planet in our solar system that was believed to orbit beyond Neptune. Lowell never found his Planet X. But in 1930, nearly three decades after his death, Clyde Tombaugh, an astronomer working at Lowell’s observatory, discovered the dwarf planet, Pluto.

Though unintentional, another major contribution made by Lowell is in the field of literature! His ideas about extra-terrestrial life, aliens on a dying planet struggling to survive, excited the public, and inspired writers of science fiction to craft the bestsellers of those times. H. G. Wells’ 1897 novel, The War of the Worlds, is one such example!

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What is Solis Lacus?

Solis Lacus, meaning “Lake of the Sun” in Latin, is a dark patch lying south of the canyon system, Valles Marineris. It is surrounded by a light-coloured region known as Thaumasia. This colour contrast, along with the way Solis Lacus seems to change in size and shape occasionally, gives it the appearance of the pupil of an eye. So it is also known as Oculus (which means “eye” in Latin), and more simply, the Eye of Mars!

Though Solis Lacus was first observed and sketched by a French-Italian astronomer, Jacques Maraldi, in 1704, it was the Italian astronomer, Giovanni Schiaparelli, who gave it its present name. But what had he seen in Solis Lacus that made him call it a lake where there was none?

During the late 1800s, astronomers were limited by the ability of their telescopes - their magnification power was low, compared to that of the telescopes of today. So Schiaparelli, who could see only light- and dark-coloured patches on Mars, thought the paler areas were continents and the darker areas were seas (“mare” in Latin) or lakes “lacus”)! The American astronomer, Percival Lowell, took this belief one step further. He thought he saw his Martian channels intersect in this dark area, and concluded that Solis Lacus was the capital city of Mars. Today we know that the changing shape of Solis Lacus is due to dust storms that frequently pass over this area.

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How did the Martian canal controversy finally resolve?

Have you heard the expression, “seeing is believing?” So even though many well-known scientists had questioned the existence of Martian canals, as far as some astronomers of the late 19th century were concerned, canals were what they saw on Mars!

The field of astronomy was also quite different back then. Observers had to manually focus their low-power telescopes on Mars, sometimes wait for hours for the image to become sharp, and make sketches to record what they saw.

Even though astrophotography (taking photographs of astronomical objects) was first attempted as early as in 1839, it had not become popular in astronomical research work till early 20th century.

The camera-equipped telescope installed in the Pic du Midi Observatory, France, in the summer of 1909 changed all that! A French astronomer, Count Aymar de la Baume Pluvinel, and his assistant, Fernand Baldet, observed Mars through the telescope and took photographs.

The images were so clear that they helped settle, once and for all, this three-decade-long canal controversy - there were no artificial canals on Mars! By this time, scientists studying the Martian atmosphere based on the way light interacted with it had also realised that Mars was a dry planet.

A clearer “picture” emerged when the U.S. National Aeronautics and Space Administration’s (NASA) Mariner 4 spacecraft took close-up photographs of the planet in 1965.

There were craters on Mars, but no canals!

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Who disputed the presence of canals on Mars?

Though Schiaparelli’s canali and Lowell’s irrigation canals may have looked fascinating on paper, most astronomers were not able to see them through their telescopes.

To settle the debate about the existence of these canals, Edward Maunder, a British astronomer, and Joseph Evans, the headmaster of a prestigious school in England, conducted an experiment in 1903. With the help of a group of schoolboys, they were able to show that the lines astronomers seemed to have seen on Mars were most likely optical illusions, or the tricks our eyes play on us! (Have you noticed that when you look at closely-spaced markings placed just outside the limits of your vision, you are sometimes able to see them as lines?)

A.E. Douglass, Lowell’s assistant at his observatory, too began to grow concerned about the influence of these illusions on their astronomical observations. But Lowell continued to believe the canals he had seen on Mars were real, and Douglass eventually had to leave his job!

Meanwhile, Alfred Wallace (a British biologist and explorer famous for his theory of evolution by natural selection - an honour he shares with Charles Darwin) also dismissed Lowell’s theories about intelligent beings on Mars in his book Is Mars Habitable? published in 1907.

Soon after, even astronomers who had initially supported the canal theory, like Eugene Antoniadi, observed Mars through better telescopes, and argued that there were no canals on Mars.

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