By Amanda Rumble • Updated Mar 24 2022
Scientists study Earth’s relationship with its neighboring terrestrial planet, Mars, to deepen our understanding of both worlds. Despite being the second planet from the Sun, Mars sits roughly 225 million miles from Earth—its distance oscillating between closest and farthest points in its orbit. While the two planets share striking similarities in axial tilt, day length, and seasonal patterns, they diverge markedly in other respects.
Earth’s axis is tilted 23.5°, giving rise to its familiar seasons. Mars tilts slightly more, at 25.2°, and its orbit moves at a velocity of 24 km/s compared with Earth’s 30 km/s. These tilt angles dictate comparable seasonal cycles on both worlds.
Both planets experience four distinct seasons. On Mars, the southern hemisphere’s summer is often dominated by planet‑wide dust storms that obscure satellite imaging, while the polar regions undergo CO₂ ice formation in the fall, temporarily drawing atmospheric gases into solid form and lowering surface pressure by up to 30 %. Earth’s seasonal weather, meanwhile, ranges from hurricanes to snowstorms, showcasing a broader spectrum of atmospheric dynamics.
A day on Earth lasts 24 hours. Mars’ rotation period is only slightly longer—24 hours 37 minutes—making it a subtle but measurable difference. One Martian year equals 687 Earth days, nearly twice as long as our own 365‑day orbit.
Mars’ thin atmosphere is 95 % carbon dioxide, with a trace 0.13 % oxygen and other gases. Earth’s breathable air is 78 % nitrogen and 21 % oxygen, supplemented by various other constituents that support complex life.
Earth’s landscape includes oceans, continents, mountains, valleys, craters, and volcanoes. Mars shares many of these landforms—valleys, impact craters, and volcanic edifices—yet lacks stable surface water, limiting its hydrological cycle.
These comparative insights not only highlight the unique character of each planet but also guide future exploration missions and our search for life beyond Earth.
