Mars/Earth Comparison Table

October 16, 2021


Mars is only about one-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 the Earth’s surface is covered by oceans, whereas the present surface of Mars has no liquid water.

Mars and Earth are very different planets when it comes to temperature, size, and atmosphere, but geologic processes on the two planets are surprisingly similar. On Mars, we see volcanoes, canyons, and impact basins much like the ones we see on Earth.

Many of the same physical land features we see on Earth also exist on Mars. But the sheer size of some landforms on Mars dwarfs that of similar features on Earth. The table below compares many of Mars’ conditions, specifications and features with those on Earth.   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) wide Grand Canyon
1.8 km (1.1 miles) deep
400 km (248.5 miles) long Distance from Sun
(average) 227,936,637 kilometers
(142,633,260 miles) 149,597,891 kilometers
(92,955,820 miles) Equatorial Radius 3,397 kilometers
(2,111 miles) 6,378 kilometers
(3,963 miles) Gravity 0.375 that of Earth 2.66 times that of Mars Largest Volcano Olympus Mons
26 kilometers (16 miles) high
602 kilometers (374 miles) in diameter Mauna Loa (Hawaii)
6.3 miles high
121 kilometers (75 miles) in diameter Length of Day
(time required to make a full rotation on its axis) 24 hours, 37 minutes Just slightly under 24 hours Length of Year
(time required to make a complete orbit of the Sun) 687 Earth days 365 days Polar Caps Covered with a mixture of carbon dioxide ice and water ice Permanently covered with water ice Surface Temperature
(average) -81 degrees F (-63 degrees C) 57 degrees F (14 degrees C) Tilt of Axis 25 degrees 23.45 degrees # of Satellites 2 (Phobos and Deimos) 1 (Moon)

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