How does the atmosphere of Mars differ from that of Earth?

Mars has a markedly thinner atmosphere compared to Earth, primarily composed of carbon dioxide, with only trace amounts of nitrogen and argon. The statement about less gravity on Mars affecting its ability to hold gases is accurate because Mars' gravitational pull is about 38% that of Earth's. This lower gravity limits the planet's capacity to retain a substantial atmosphere over geological time scales, leading to atmospheric loss into space.

On Earth, the dense atmosphere supports a complex mix of gases, including a significant concentration of nitrogen (approximately 78%), which plays a critical role in supporting life and weather patterns. The difference in atmospheric composition is crucial in understanding the viability of each planet for maintaining liquid water and supporting life.