Earth and Mars – a comparison | Earth vs Mars

The following is a comparison between Earth and Mars, the third and fourth planet from the sun respectively.

Earth and Mars – a comparison

Earth vs Mars – size comparison

Earth is the fifth largest planet in the solar system. Among the terrestrial planets (Mercury, Venus, Earth, and Mars), Earth is the largest. Mars is the second smallest planet in the solar system after Mercury.

Solar system planets
Solar system planets

Earth diameter – 12,742 kilometers (7917.5 miles)
Mars diameter – 6,779 kilometers (4,212 miles)


Earth has a single moon. Earth’s moon is one of the largest natural satellites in the Solar System. Mars has two small irregular-shaped moons – Phobos and Deimos.

Gravity on Earth vs Mars

If an object weighs 100 N on Earth, it will weigh about 38 N on Mars. The weight of an object on Mars is 37.94% of its weight on Earth.

Gravity on Earth vs Mars

Acceleration due to gravity on Mars = 3.721 m/s²
Acceleration due to gravity on Earth = 9.8 m/s²


The atmosphere on Mars is very thin. The atmospheric pressure is just 6.518 millibars. The atmospheric pressure on Earth is 1.013 bar.

Mars atmosphere composition

Carbon Dioxide – 95%, Nitrogen – 2.6%, Argon – 1.9%, Oxygen – 0.16%, Carbon Monoxide- 0.06%

Earth atmosphere composition

Nitrogen – 78.08%, Oxygen – 20.95%, Argon – 0.9340%, Carbon Dioxide – 0.9340%

(Also read: Percentage of oxygen in the air | oxygen at high altitudes | Ozone)

Ice caps

Northern ice cap of Mars

Both Earth and Mars have polar ice. The top of polar ice caps on Mars is made of carbon dioxide ice which forms during fall and winter and disappears during summer. Under the carbon dioxide ice lies the stable water ice.



Mars is a relatively colder planet. The average temperature on Mars is -65°C (-85°F). The average temperature on Earth is 15°C (59°F).

Axial tilt

Both of these planets have similar axial tilts. Earth’s rotational axis is tilted at an angle of about 23.5 degrees with respect to a perpendicular to the orbital plane. Mars’ axis is tilted at an angle of about 25 degrees.

Day and year

Due to similar axial tilts, Earth and Mars have almost equal day lengths.

1 day on Mars = 24.62 hours
1 day on Earth = 23.934 hours

1 year on Mars is almost equal to 1.9 Earth years.

1 year on Mars = 687 Earth days
1 year on Earth = 365 days

Mars is located near the outer boundary of the habitable zone

The habitable zone is a region in a solar system where liquid water can exist on a planet’s surface given the atmospheric conditions are right. Mars is located near the outer boundary of our Solar system’s habitable zone. Earth is well within the habitable zone.

Highest mountain

Olympus Mons

The highest mountain on Mars is Olympus Mons. It is 21.9 km (13.6 mi) high. This means that Olympus Mons is almost 2.5 times as high as Mount Everest (8,848.86 meters). Mars is not a very big planet and something like Olympus Mons to exist on Mars is really mind-boggling. Olympus Mons is actually a shield volcano.

Surface area

Mars has a total surface area of about 145 million square kilometers. The open land on Mars and Earth is about the same as 71 percent of Earth’s surface is water.

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