Mars, named for the Roman god of war, is a cold desert world of polar ice caps, volcanoes and canyons. While traces of water have been discovered on Mars, the atmosphere is so thin that liquid does not last long on the planet. It is commonly called the 'red planet' due to the iron oxide on the surface that gives off a reddish appearance.

 

The planet is difficult to see from Earth, but telescopic viewing shows that Mars has seasons thanks to its tilted rotational axis, like Earth’s. During these seasons, the polar ice caps grow and recede. A day on Mars is just slightly longer than a day on Earth, clocking in at around 24 hours and 39 minutes, while a Martian year is almost two Earth years.

 

The presence of water on the planet has long been theorized due to the presence of dark patches of land (initially assumed to be vegetation) and the ice caps. Various missions to Mars, including the Mars Odyssey spacecraft and the exploration rovers Spirit and Opportunity, have found evidence of ancient water on the planet.