Mars Facts
Everything you need to know about the Red Planet — in bite-sized form.
Atmosphere is 95% Carbon Dioxide
The Martian atmosphere is composed of approximately 95.3% carbon dioxide, 2.7% nitrogen, 1.6% argon, and trace amounts of oxygen and water vapor. This makes it unbreathable for humans without life support.
Surface Gravity is 38% of Earth's
Mars has a surface gravity of 3.72 m/s² — about 37.6% of Earth's 9.8 m/s². A 150-pound person would weigh roughly 57 pounds on Mars. This lower gravity affects everything from human physiology to how buildings must be constructed.
A Martian Day is 24 Hours and 37 Minutes
A Martian solar day — called a sol — lasts 24 hours, 39 minutes, and 35 seconds. This is remarkably close to an Earth day, making Mars among the most practical of all planets for human biological adaptation.
Olympus Mons is the Tallest Volcano in the Solar System
At approximately 22 km high and 600 km in diameter, Olympus Mons dwarfs Mount Everest by nearly three times. It is a shield volcano so wide that standing at its base, you cannot see the summit — it lies beyond the horizon.
Valles Marineris Would Span the United States
The Valles Marineris canyon system stretches about 4,000 km long — roughly the distance from New York to Los Angeles. In places it reaches 7 km deep and 200 km wide, dwarfing the Grand Canyon.
Mars Has Two Tiny Moons
Phobos and Deimos are Mars's two small, irregularly shaped moons, likely captured asteroids. Phobos orbits so close to Mars that it completes an orbit in just 7 hours 39 minutes — faster than Mars rotates — and will eventually crash into the planet in roughly 50 million years.
Temperatures Swing Wildly
Surface temperatures on Mars range from about -195°F (-125°C) at the poles in winter to about 70°F (20°C) near the equator on a summer afternoon. The thin atmosphere means these swings can occur within a single day.
Water Ice Exists at the Poles and Underground
Mars has confirmed water ice at both polar caps and in the shallow subsurface at mid-to-high latitudes, confirmed by the Mars Odyssey orbiter and the Phoenix lander's direct excavation. This is the most critical resource for any future human settlement.
Mars Once Had a Global Magnetic Field
Remnant magnetic signatures in ancient rocks indicate Mars once had a global magnetic field similar to Earth's. It ceased about 4 billion years ago when the planet's core cooled, after which the solar wind gradually stripped away much of the atmosphere.
Dust Storms Can Engulf the Entire Planet
Mars experiences regional and occasionally planet-wide dust storms that can persist for months. The 2018 global dust storm blanketed the entire planet and caused NASA's Opportunity rover to lose power permanently after 15 years of operation.
MOXIE Proved Oxygen Can Be Made on Mars
In April 2021, NASA's MOXIE aboard Perseverance produced 5.37 grams of oxygen from the Martian atmosphere — enough for roughly 10 minutes of breathing. It proved the technology that could supply both air and rocket propellant for future missions.
Hellas Planitia is the Deepest Basin on Mars
The Hellas Planitia impact basin is approximately 7.2 km deep and 2,300 km wide. At its floor, atmospheric pressure is roughly double the Martian average — making it a prime candidate for early human settlement.
A Mars Year is About Two Earth Years
Mars takes 686.97 Earth days to complete one orbit. Earth and Mars align for efficient travel only once every 26 months, making launch windows precious for mission planners.
Mars Has Seasons Like Earth
Because Mars has an axial tilt of 25.19° (very close to Earth's 23.44°), it experiences four distinct seasons. Mars's more elliptical orbit means the southern hemisphere has shorter, more intense summers.
Ingenuity Made First Powered Flight on Another Planet
On April 19, 2021, NASA's Ingenuity helicopter hovered for 39 seconds on Mars — the first powered, controlled flight on another planet. It carried fabric from the Wright Brothers' original Flyer.
Mars is Half the Size of Earth
Mars has a diameter of 6,779 km — about 53% of Earth's. Its surface area equals the total land area of all Earth's continents combined, despite being a much smaller planet.