Mars/Earth Comparison Table

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.

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%)
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
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)
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
-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)