A full image of Mars, with white polar ice caps at the top and bottom.

Gibbous Mars. Image courtesy of Flowers Gallery. © ESA/Michael Benson, Kinetikon Pictures

Factfile: Mars

Watery world or desert planet? Mars holds secrets that are still being uncovered today.

Few places, either on Earth or in space, have captured our collective imagination like Mars. Since the earliest observations with telescopes, which revealed a world with polar caps and seasonal changes, we have speculated about the presence of life on the red planet.

The 'discovery' by Italian astronomer Giovanni Schiaperelli of lines on the Martian surface further fuelled these ideas. He called the markings canali, meaning channels, but many people believed he had found canals, built by an intelligent civilisation.

Although Schiaperelli's channels were later found to be an optical illusion, the idea of life - and water - on Mars has never gone away.

Hidden water

In fact, millions of years ago, Mars may have had lakes and seas like those on Earth. However, the planet's atmosphere is too thin for water to remain on its surface as a liquid.

But as these images, taken from the 77 composite photographs appearing in Otherworlds: Visions of our Solar System, demonstrate, this doesn't mean Mars is completely dry.

Instead, its water takes on other forms.

Its polar caps contain two to three million cubic kilometres of water ice - which, if melted, would be enough to cover the entire planet to a depth of 20 to 30 metres.

And the Valles Marineris, a canyon system over three times deeper than the Grand Canyon, is often covered in a water vapour ground fog.

A photograph from space of the Valles Marineris, a huge cross-shaped canyon on the surface of Mars

The Valles Marineris Canyon System. Image courtesy of Flowers Gallery. © NASA; JPL; Dr. Paul Geissler/Michael Benson, Kinetikon Pictures


Even the planet's surface, which interacted with water millions of years ago, contains some water locked away in its rocks.

Audio commentary extract

If there's water, could there be life? Dr Joe Michalski, Planetary Scientist at the Museum, explains how Martian rocks could provide evidence for ancient bacterial life on Mars - and what the work could tell us about the origin of life on Earth.

Extraterrestrial materials

Discover more about Museum research on the Moon, Sun, Mars, comets and asteroids.