1-152-578 - Ann Ronan Picture Library/Heritage-Images

Drawings of Mars showing its 'canals' and polar ice caps, 1907. These drawings are from observations made at the Lowell Observatory, Flagstaff, Arizona, USA, on 8-12 July, 1907. The American astronomer Percival Lowell (1855-1916) theorised that a Martian civilization, faced with climate change, had built the canals to transport water from the planet's ice caps to irrigate crops. In fact the canals did not exist; they are now thought to have been optical illusions possibly caused by dust storms.