Mars, the fourth planet from the Sun, is often called the Red Planet due to the iron oxide (rust) covering its surface, giving it a reddish hue visible even from Earth. It is about half the size of Earth, with a thin atmosphere composed mostly of carbon dioxide, which cannot retain much heat, causing extreme temperature swings from about 20°C (68°F) during the day to -125°C (-195°F) at night. Mars is home to the largest volcano in the solar system, Olympus Mons, standing nearly three times the height of Mount Everest, and the deepest canyon, Valles Marineris, which stretches over 4,000 km. The planet’s surface features vast deserts, polar ice caps made of water and dry ice, and evidence of ancient riverbeds, suggesting that liquid water once flowed there billions of years ago. A Martian day, called a sol, is about 24.6 hours—remarkably close to Earth’s—and a year lasts 687 Earth days. Mars has two small, irregularly shaped moons, Phobos and Deimos, believed to be captured asteroids. Numerous missions, including NASA’s rovers Spirit, Opportunity, Curiosity, and Perseverance, as well as orbiters from multiple countries, have been exploring Mars to study its geology, climate, and potential for past or present microbial life. Scientists are particularly interested in Mars as a possible destination for future human colonization, though challenges like low gravity, radiation exposure, and lack of breathable air must be overcome. Mars remains one of the most intriguing worlds in our solar system, holding clues about planetary evolution and the possibility of life beyond Earth.