No other planet has captured the human imagination quite like Mars. The fourth planet from the Sun, it has been the target of dozens of missions and remains the leading candidate for future human exploration. Its rusty colour, visible even to the naked eye, comes from iron oxide, essentially rust, coating its surface.
A smaller, colder world
Mars is roughly half the diameter of Earth and far colder, with average temperatures around minus 60 degrees Celsius. Its thin atmosphere is more than 95 percent carbon dioxide and far too sparse to keep the planet warm or to allow liquid water to remain stable on the surface for long. A day on Mars, called a sol, lasts about 24 hours and 37 minutes, remarkably close to our own.
Dramatic landscapes
Mars is a planet of superlatives. It hosts Olympus Mons, the largest volcano in the Solar System at nearly three times the height of Mount Everest, and Valles Marineris, a canyon system so vast it would stretch across the entire United States. Towering dust storms can occasionally swallow the whole planet for weeks at a time.
The search for water and life
Ancient riverbeds, lakebeds and minerals that only form in water tell us that Mars was once far wetter and warmer than it is today. Now, water survives mainly as ice at the poles and beneath the surface. Rovers such as Perseverance are searching for chemical signs that microbial life may once have existed, and are caching samples for a future return to Earth.
The next giant leap
Space agencies and private companies alike are working toward sending humans to Mars in the coming decades. The challenges are immense, from radiation exposure during the months-long journey to growing food and producing oxygen on arrival. Yet Mars remains the most realistic destination for the first humans to walk on another planet.
