Google has expanded its online mapping services, offering ordinary users the chance to explore the surface of an alien planet for the very first time.
Man has gazed at the surface of Mars for hundreds of years
Google Mars allows users to view the surface of the Red Planet either by a colour-coded altitude map, black and white photographs, or an infra-red map.
The launch follows the success of Google Earth, which allows detailed exploration of our planet's surface.
Another service, Google Moon, lets users view the sites of moon landings.
The maps used on Google Mars were made from images captured by Nasa probes Mars Odyssey and Mars Global Surveyor, both currently orbiting the planet.
It launched the service to mark the 151st anniversary of the birth of Percival Lowell, an astronomer who mapped and studied Mars in the 19th century.
Google worked with planetary scientists at Arizona State University in the US to develop digital versions of the Martian surface.
Although most of the maps are readily available on the internet through Nasa websites, Google said its project is the first time ordinary users can explore the planet in such detail.
Users can explore Martian features like the Valles Marineris
"The idea is to look at Mars and not think of it as a mysterious alien place," said Phil Christensen of Arizona State University.
Using similar techniques made popular by Google Earth, users can zoom in on the Martian surface, with key landmarks highlighted.
Mountains, craters, canyons and dunes are all easily identified.
The maps also mark the sites of a series of previous missions to Mars, including the final landing site of the British probe Beagle 2, which launched in 2003 but failed on landing.
Would-be interplanetary explorers can wander the surface of Mars from within their standard web browser, instead of having to download a separate software program, such as Google Earth.