Mars and Earth are both rocky planets and share some similarities, like having seasons, polar ice caps, and volcanoes, but they also have many important differences that affect their ability to support life.

First, Mars is much smaller than Earth-about half the diameter and one-tenth the mass. This smaller size gives it weaker gravity, which is only 38% of Earth’s. If you weigh 100 pounds on Earth, you’d weigh only 38 pounds on Mars.

Second, Mars has a thin atmosphere, made mostly of carbon dioxide. Earth’s thick atmosphere protects us from harmful space radiation and keeps the planet warm. Mars’s thin air cannot trap heat well, so temperatures drop quickly—average surface temperatures are around minus 60°C, though it can be much colder at night.

Mars also lacks a global magnetic field, which on Earth protects us from solar and cosmic radiation. Without it, Mars’s surface is exposed to high levels of radiation, making it dangerous for humans without protection.

Another difference is water. While Earth has abundant liquid water, Mars only has ice and maybe small amounts of briny liquid underground. However, ancient river valleys and lakebeds on Mars show it once had flowing water billions of years ago.

Mars is also known for its dust storms, some of which can cover the entire planet and last for months. These storms can disrupt solar power and reduce visibility, posing challenges for missions.

While Mars and Earth share a few features, Mars is a colder, drier, and more hostile world. Understanding these differences is key to planning future missions and exploring whether life could ever survive there.