Asking ourselves or trying to compare two planets or celestial bodies is quite common, since observation from the earth does not make it easy to know their size. For example, Is the moon 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 Moon 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 volume, surface area or radius, and also using the Earth as a reference since it is the planet we know best.
Size of the Moon
The volume of the Moon is 2.19 x 1010 km³ (0.02 times the volume of the Earth). The mean radius of the Moon is 1737.4 km (0.27 times the radius of the Earth) consequently the diameter of the Moon is 3474.8 km. If we take into account the surface area, the Moon is 3.79 x 107 km² (13.5 times less than the 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 consequently 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 the Moon compared to Earth?
The Moon is much smaller than Earth, taking into account the volume which is the easiest metric to visualize. The Moon is 2.19 x 1010 km³ and the Earth using the same exponent 108 x 1010 km³.
How many times larger is Earth than the Moon?
Earth is practically 50 times bigger than the Moon taking into account the volume, and if we compare the surface of Earth it is 13.5 times larger than the Moon (51 x 107 km² of Earth vs 3.79 x 107 km² of the Moon).
Is the mass of the Moon larger than Earth?
Usually to a comparative question between two planets, or in the case of Earth and the Moon a planet and its satellite, 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 the Moon is 3.344 g/cm³ and the density of Earth is 5.514 g/cm³.
Considering that the volume of the Moon is 0.02 times the volume of Earth and the density of the Moon is 0.606 the density of Earth we can be sure that the mass of the Moon is smaller than Earth.
The mass of Earth is 5.972 x 1024 kg and the mass of the Moon is 7.342 x 1022 kilograms (81.3 times less than Earth).
Is gravity on the Moon bigger than Earth?
Gravity is not a value for size comparison, 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 the Moon
The gravity on the Moon, the only natural satellite of Earth, is 1.622 m/s², equivalent to 0.1654 g.
Gravity on Earth
Earth’s gravity is 9.806 m/s², 1 g.
If what we want to know is whether gravity is greater on the Moon or Earth, we must inform you that gravity is smaller on the Moon.
Other data of interest in the comparison between the Moon and Earth
The Moon orbits around the Earth and the Earth orbits around the Sun.
The time it takes the Moon to make a complete orbit around Earth is 27.32 days and in the case of the orbit of Earth around the Sun it is 365.25 days.
We can not assign a rotation time to the Moon since the rotation of the Moon is fixed to Earth due to tidal locking which means that from the Earth we always see the same face of the Moon.
The rotation time of Earth is approximately 24 hours (23h 56 min) so the statement that the rotation time is exactly 1 day is not 100% correct.
Conclusion of our Moon vs Earth comparison
As we have seen from the data provided in the comparison, the Moon is much smaller than Earth. There is no metric mentioned in which the Moon can be considered larger.
However, the Moon is not a small satellite. It is the second largest satellite in the entire Solar System. Furthermore if we compare the ratio of satellite to parent planet, the Moon is the satellite with the largest ratio.
Other planets and satellites compared with Earth
All information has been extracted from Wikipedia.
Photo by David Besh