Astronomers and philosophers have been interested in life on other planets for hundreds of years and Mars is usually the planet that inspires them most. With its bright red colour, it is associated with the God of war, and is probably the most likely planet to have life. This possibility has inspired many stories about little green men, known as Martians.

Interest in the planet grew during the 19th century when more accurate telescopes became available and two astronomers thought they saw signs of life there. In 1877 Italian Giovanni Schiaparelli identified what he thought were Martian made irrigation canals and in 1884 the American Percival Lowell saw something he thought was vegetation there. These observations inspired H.G. Wells to write his now famous War of the Worlds in which an advanced civilisation of Martians attack the earth but are finally destroyed by our bacteria.

Later, more advanced telescopes proved that the water canals were just optical illusions but this did not stop interest in the planet. In July 2018, scientists identified what is possibly a lake of water, 1.6 km under the planet’s surface. It is the nearest we have come to discovering if there really is life on Mars.

Illustration by ​Franco Rivolli, taken from Alien Alert in Seattle by Gina D.B. Clemen, Reading and Training, Step 1 (A2)