The Moon vs Io (How Are They Different?)

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The main differences between the Moon and Io is that the Moon is Earth’s only moon whilst Io is a Galilean moon and 1 out of 79 moons that orbit Jupiter, The moon is the 5th largest natural satellite in our solar system with a diameter of 3,474.8km whilst Io is 4th with a diameter of 3,643km and Io is the most volcanically active entities in our solar system whilst the Moon has no volcanic activity.

There are numerous other differences between the two so, continue reading for amore detailed look at each of these celestial bodies along with their similarities and differences below.

What Is The Moon?


The moon is the gray celestial being that orbits our Earth. It is also tidally locked to Earth meaning that we only see one side of it at any time in our sky.

It takes the moon roughly 27 days to complete an orbit around Earth, which it does in an elliptical pattern. The Moon’s axial tilt is very straight at 1.5 degrees. As a result of the tidally locked status along with the effects that Earth has on its general rotational patterns, it takes the Moon roughly 29.5 days to complete a day.

In regards to its temperature, it fluctuates where it can be really hot at 127 degrees Celsius when the Sun is shining on it and to -173 degrees in areas where the Sun does not strike it. It’s core on the other hand is far hotter ranging between 1,327 to 1,427 degrees Celsius.

This is as a result of the lunar entity’s extremely thin to practically non-existent atmosphere, which not only results in these massive temperature shifts but, is also the reason why it has over 100,000 craters on its surface.

Speaking of the Moon’s surface, the entity is mostly made of rocks, iron, magnesium just like most of the other moons and terrestrial based planets in our solar system.

It is among the bigger moons in our solar system with a diameter of 3,474.8km and a mass of 7.35 × 10^22 kg, which actually places it fifth amongst all moons in our solar system and would also make it bigger than the dwarf planet Pluto.

Despite all the advancements in technology, the last time a manned mission was made to the Moon was on the Apollo 17 way back in December 1972 and no further missions have been done since, possibly as result of the political agendas behind the numerous countries vying for opportunities that we don’t know of.

What Is The Moon Io?


The Moon Io – also known as Jupiter I – is the third largest of the Galilean moons, which has the closest orbit to Jupiter. It is the fourth-largest moon in our solar system by size – with a diameter of 3,643km – but has the highest density of all moons in the Milky Way.

In addition, Io has the strongest surface gravity of all moons and the least water by atomic ratio compared to any other astronomical object in our solar system.

Perhaps the most interesting feature of this lunar body is the 400 active volcanoes on its surface, which make it the most volcanically active object in the Milky Way; some of these volcanoes can exude plumes of sulfur to a height of several hundred miles.

The reason for this intense activity is the tidal heating caused by friction in the moon’s interior. Thanks to Io’s proximity to Jupiter, it finds itself caught between the gravity of its planet plus the two nearby moons – Ganymede and Europa. And this creates extreme tidal forces.

A side effect of these tidal forces is heat, which keeps most of Io’s crust in liquid form. Because of this, the surface of Io experiences a constant state of renewal; sites once home to large craters are slowly filled with molten lava and liquid rock.

While the complete makeup of Io’s surface is not yet defined, theories suggest that its main component could be sulfur and sulfur compounds because of the varied coloring. Silicate rock could also be a likely component as it would account for the high temperatures.

Io orbits Jupiter from a distance of around 422,000km, with an orbit that takes 42.5 hours to complete. Sitting 778,000,000km from the Sun, the surface temperature of this planet sits around -130 degrees Celsius. But due to the intense volcanic activity, the lava flows can reach temperatures of 1649 degrees Celsius, which is far hotter than anything on Earth.

Similarities Between The Moon And Io

As both are natural satellites, the Moon and Io do share a few similarities, which in this case includes the following:

  • Both have a hotter central core.
  • Both have a rocky, terrestrial surface.
  • Both are spherical in shape.
  • Neither have rings surrounding them.
  • Both are tidally locked to their planet.
  • Both orbit their planet in an elliptical pattern.
  • Neither have tectonic plates.
  • Both have a practically non-existent atmosphere.
  • Neither have a magnetosphere.

Differences Between The Moon And Io

As for the differences between the two, they would include the below.

  • Io is the most volcanically active body in our solar system whilst the Moon has no volcanic activity.
  • The Moon has a heavily cratered surface, whilst any craters on Io are filled in by the molten lava that oozes across its surface.
  • Io is the bigger of the two with a diameter of 3,643km whilst the Moon has a diameter of 3,474.8km.
  • The orbital period of the Moon is 28 days whilst Io’s orbit around Jupiter is 42 hours.
  • A day on the Moon takes 29.5 days whilst a day on Io is between 42 – 43.
  • The Moon’s density is 3.34 g/cm³ whilst Io’s is 3.53 g/cm³.
  • Io’s gravitational strength is 1.796 m/s² whilst the Moon’s is 1.62 m/s².
  • In regards to mass, the Moon’s is 7.35 × 10^22 kg whilst Io’s is 8.93 × 10^22 kg.
  • The Moon’s temperature fluctuates from a very hot 127 to a chilling -173 degrees Celsius whilst Io’s averages around -130 degrees Celsius.


Although the Moon and Io are amongst the largest and densest moons in our solar system, there are a number of core features that really separate the two,

Whether it be in regards to their surface activity where Io is know for being the most volcanically active natural satellite to the temperature differences and heavily cratered surface of the Moon, the planets they orbit and gravitational strength, the two ultimately operate distinctly from one another.

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