Some 19th and early 20th century astronomers thought they could see linear marks on Mars and speculated that they were an alien civilisation's canals. The Italian astronomer Giovanni Schiaparelli and others named the features canali, Italian for channels.
The American Percival Lowell popularised the idea that intelligent life forms had created the canals, as the features came to be known. Many other astronomers were sceptical. It is now thought that well-intentioned pioneers mistook ordinary Martian surface features for canals.
Photo: Map showing Martian canals (Illustrated London News Ltd/Mary Evans)
Early telescopes and active imaginations create controversy.
The Viking orbiters see evidence of past water on Mars.
Viking orbiters mapped Mars in unprecedented detail and returned strong evidence of past flowing water. This finding suggested that the Red Planet may have once supported life.
A wealthy Bostonian is intrigued by talk of canals on the Red Planet.
The American astronomer Percival Lowell popularised the idea that an advanced civilisation built canals on Mars, and he drew elaborate maps of their irrigation network. Many astronomers at the time were sceptical. It is now thought that surface features were mistaken for canals by well intentioned pioneers.
As the Sun ages, Mars may reawaken and support life.
As the Sun gets brighter towards the end of its life, it is predicted that water ice on Mars may melt, transforming the Red Planet into a place that could support human life.
Percival Lowell describes Martian farms and canals.
The 19th and early 20th century American businessman and astronomer Percival Lowell popularised the idea that a race of canal-building beings lived on Mars. He observed Mars through telescopes and mapped the planet in detail. Historians and astronomers now believe Lowell mistook faint surface features for canals or imagined he saw them.
For a time in the late 19th and early 20th centuries, it was erroneously believed that there were canals on Mars. These were a network of long straight lines in the equatorial regions from 60° N. to 60° S. Lat. on the planet Mars. They were first described by the Italian astronomer Giovanni Schiaparelli during the opposition of 1877, and confirmed by later observers. Schiaparelli called these canali, which was translated into English as "canals". The Irish astronomer Charles E. Burton made some of the earliest drawings of straight-line features on Mars, although his drawings did not match Schiaparelli's. By the early 20th century, improved astronomical observations revealed the "canals" to be an optical illusion, and modern high resolution mapping of the Martian surface by spacecraft shows no such features.