Mars is a terrestrial, or rocky, planet similar to Earth, Mercury, and Venus. It has a solid surface composed mainly of iron, magnesium, aluminum, calcium, and potassium, with a crust thickness ranging from about 6 to 30 miles (10 to 50 kilometers). Beneath the crust lies a rocky mantle and a dense core made primarily of iron, nickel, and sulfur

. Mars is often called the "Red Planet" due to the iron in its surface rocks and dust oxidizing (rusting), giving it a reddish appearance

. It is a cold, desert-like world with a very thin atmosphere mostly composed of carbon dioxide. The planet features polar ice caps, extinct volcanoes, canyons, and weather phenomena such as dust storms

. Physically, Mars is about half the diameter of Earth and has roughly the same surface area as Earth's dry land. Its surface gravity is about 38% that of Earth. The planet's environment is harsh, with temperatures ranging from about -153°C to 20°C and a very thin atmosphere that cannot sustain liquid water on the surface for long

. In summary, Mars is a rocky terrestrial planet characterized by its red color, thin carbon dioxide atmosphere, cold desert conditions, and geological features like volcanoes and canyons, making it distinct yet somewhat Earth- like in structure