Mars

Mars is often called the Red Planet because of its distinctive rusty-red color caused by iron oxide (rust) on its surface. It is the fourth planet from the Sun and the most Earth-like of all the planets in our solar system. Scientists have long been fascinated by Mars because it shows clear evidence of a much wetter and warmer past.

Mars is a rocky planet about half the size of Earth. Its thin atmosphere is made mostly of carbon dioxide, and its surface features some of the most dramatic geology in the solar system, including the tallest mountain and the longest canyon anywhere in the solar system.

Surface and Geology

The Martian surface is covered with ancient riverbeds, dried-up lake beds, and vast polar ice caps made of water ice and frozen carbon dioxide. Olympus Mons, the largest volcano in the solar system, rises 13.6 miles (22 km) above the surrounding plains — more than twice the height of Mount Everest. Nearby lies Valles Marineris, a canyon system so large it would stretch across the entire United States.

Strong winds on Mars create massive dust storms that can sometimes engulf the entire planet for weeks or months at a time. These storms give the planet its characteristic red hue when viewed from Earth.

Key Facts About Mars

Diameter: 4,212 miles (6,779 km) — roughly half the size of Earth
Mass: 0.107 times Earth’s mass
Distance from the Sun: 142 million miles (1.52 AU) on average
Day Length: 24 hours and 37 minutes (very similar to Earth)
Year Length: 687 Earth days
Average Surface Temperature: -81°F (-63°C)

Evidence of Past Water and Current Exploration

Spacecraft and rovers have found clear signs that liquid water once flowed across Mars billions of years ago. Ancient river valleys, mineral deposits that only form in water, and possible dried lake beds all point to a time when Mars may have had a thicker atmosphere and liquid oceans or lakes on its surface.

Today, several robotic missions are actively exploring Mars. NASA’s Perseverance rover is collecting samples that may one day be returned to Earth, while the Ingenuity helicopter became the first aircraft to fly on another planet. Orbiters from multiple countries continue to map the surface in incredible detail and search for underground ice deposits.

Mars remains the most promising target for future human exploration. Its relatively mild temperatures, available resources, and shorter travel time compared to the outer planets make it the leading candidate for the first crewed missions beyond the Moon.

Whether Mars ever hosted life — even simple microbial life — is still one of the biggest unanswered questions in planetary science. Every new discovery brings us closer to understanding whether Earth is truly unique or if life has appeared on other worlds in our solar system.