Mars/Earth Comparison Table

 

October 16, 2021

Mars is only about half the diameter of Earth, but both planets have roughly the same amount of dry land surface area. This is because over two-thirds of Earth’s surface is covered by oceans, whereas Mars currently has no liquid water on its surface.

While Mars and Earth differ greatly in temperature, size, and atmosphere, their geologic processes are surprisingly similar. On Mars, we observe volcanoes, canyons, and impact basins that resemble those found on Earth.

Many physical land features on Earth also exist on Mars. However, some Martian landforms are far larger than their Earthly counterparts. The table below compares several conditions, specifications, and features of Mars and Earth:

Feature	Mars	Earth
Atmosphere (composition)	Carbon dioxide (95.32%) Nitrogen (2.7%) Argon (1.6%) Oxygen (0.13%) Water vapor (0.03%) Nitric oxide (0.01%)	Nitrogen (77%) Oxygen (21%) Argon (1%) Carbon dioxide (0.038%)
Atmosphere (pressure)	7.5 millibars (average)	1,013 millibars (at sea level)
Deepest Canyon	Valles Marineris 7 km (4.35 miles) deep 4,000 km (2,485 miles) long	Grand Canyon 1.8 km (1.1 miles) deep 400 km (248.5 miles) long
Distance from Sun (average)	227,936,637 km (142,633,260 miles)	149,597,891 km (92,955,820 miles)
Equatorial Radius	3,397 km (2,111 miles)	6,378 km (3,963 miles)
Gravity	0.375 that of Earth	1 g (2.66 times that of Mars)
Largest Volcano	Olympus Mons 26 km (16 miles) high 602 km (374 miles) in diameter	Mauna Loa (Hawaii) 6.3 miles high 121 km (75 miles) in diameter
Length of Day (rotation period)	24 hours, 37 minutes	Just under 24 hours
Length of Year (orbital period)	687 Earth days	365 days
Polar Caps	Carbon dioxide ice mixed with water ice	Permanently covered with water ice
Surface Temperature (average)	–81°F (–63°C)	57°F (14°C)
Tilt of Axis	25 degrees	23.45 degrees
Number of Satellites	2 (Phobos and Deimos)	1 (Moon)