Is Mercury bigger than Earth?

David Girones

Updated on:

Mercury shot from Earth

Asking ourselves or trying to compare two planets is quite common, since observation from the Earth does not make it easy to know their size. For example, Is Mercury bigger than Earth? Sometimes it is difficult to remember their sizes or how they compare to each other or we simply have a total lack of knowledge on the subject. 

Size of Mercury vs Earth

Taking into account that the planets have a spherical shape (spheroid in some cases) the best way to compare their sizes is using geometric measures such as surface area, volume or radius, and also using the Earth as a reference since it is the planet we know best.

Size of Mercury

The volume of Mercury is 6.083 x 1010 km³ (0.056 times the volume of Earth). The mean radius of Mercury is 2440 km (0.383 times the radius of Earth) consequently the diameter of Mercury is 4880.0 km. If we take into account the surface area, Mercury is 7.48 x 107 km² (6.8 times less than Earth).

Size of Earth

The volume of Earth, the blue planet, is 1.08 x 1012 km³. The mean radius of Earth is 6371 km therefore the diameter of Earth is 12742 km. If we take into account the surface area, Earth is 5.1 x 108 km².

So answering the question:

How big is Mercury compared to Earth? 

Mercury is much smaller than Earth, taking into account the volume which is the easiest metric to visualize. Mercury is 6.083 x 1010 km³ and Earth if we use the same exponent 108 x 1010 km³.

How many times larger is Earth than Mercury?

Earth is 17.86 times bigger than Mercury taking into account the volume, and if we compare the surface of Earth it is 6.80 times larger than Mercury (51 x 107 km² of Earth vs 7.48 x 107 km²  of Mercury).

Is the mass of Mercury larger than Earth?

Usually to a comparative question between two planets we want to know which of the two has a larger volume. However, there is another unit of measurement that can also be used in the comparison and that is their mass or weight.

Mass is the combination of two metrics such as volume and density.

The volume of both celestial bodies has been mentioned above, and in the case of density, we can report that the density of Mercury is 5.427 g/cm³ and the density of Earth is 5.514 g/cm³. 

Considering that the volume of Mercury is 0.056 times the volume of Earth and the density of Mercury is 0.984 the density of Earth we can be sure that the mass of Mercury is smaller than Earth.

The mass of Mercury is 3.301 x 1023 kg and the mass of Earth is 5.972 x 1024 kg (18.18 times less than Earth).

Is gravity on Mercury bigger than Earth?

Gravity is not related with the size of the planets, however gravity can be compared between different planets, satellites or stars.

Gravity calculates the force with which objects with mass are attracted to each other and is usually a value calculated for all celestial bodies.

The unit of measurement used to refer to gravity is m/s² or also a standardized unit called g which is equivalent to earth’s gravity (9.80665 m/s²).

Gravity on Mercury

The gravity on Mercury, the smallest planet in the Solar System, is 3.70 m/s², equivalent to 0.38 g.

Gravity on Earth

Earth’s gravity is 9.806 m/s², 1 g.

If we want to know whether gravity is greater on Mercury or Earth, we must inform you that gravity is lower on Mercury.

Other data of interest in the comparison between Mercury and Earth

Mercury and Earth orbit around the Sun. 

The time it takes Mercury to make a complete orbit around the Sun is 87.97 Earth days and in the case of the orbit of Earth it is 365.26 days. 

The rotation time of Mercury is approximately 176 days and the rotation time of Earth is approximately 1 day.

The distance from Mercury to the Sun is 0.387 AU and the distance from Earth to the Sun is 0.997 AU. Consequently Mercury is closer to the Sun than Earth.

AU means astronomical unit and it is a unit of length, roughly the distance from Earth to the Sun and equal to 150 million kilometers (93 million miles) or 8.3 light-minutes. The distance used is the semi-major axis of the orbit of the planet around the sun.

Conclusion of our Mercury vs Earth comparison

As we have seen from the data provided in the comparison, Mercury is smaller than Earth and there are no metrics mentioned above in which Mercury can be considered bigger than Earth.

Mercury is the closest planet to the Sun. However it is much smaller than all the other planets of the Solar System. When Pluto was considered a Solar System planet Mercury was not the smallest.

Other planets and satellites compared with Earth

Sources Used:
All information has been extracted from Wikipedia.

Photo by ZCH