Every planet has its own number of moons but Jupiter, it has considerably more than the other planets of the Solar System. What is the reason for this?
Why does Jupiter have so many Moons? It is commonly accepted among the scientific community that Jupiter has many moons due to the “Capture Theory”. Jupiter is the largest planet in the Solar System. It has the largest sphere of influence due to its size and relative distance from the Sun. This gives it an enormous gravitational pull that has captured celestial objects which in turn have become orbital moons.
How Many Moons Does Jupiter Have?
There are around 200 moons in our solar system and over a third of those belong to the planet Jupiter.
At the time of writing, 79 moons have been identified to orbit Jupiter.
Jupiter has the most moons of any planet and astronomers continue to discover more over time.
Only recently, (in 2018) 12 new moons were discovered by a team of astronomers at the Carnegie Institution of Science headed by Scott Shepard, taking the total to where it is today (79).
Why Does Jupiter Have So Many Moons?
The principal reason why Jupiter has the highest number of moons compared to other planets is due to its relative size and distance from the sun. This leads to a huge sphere of influence.
The majority of moons, especially those of gas giants, do not “form”, and instead are “captured” (this is different from the Earth’s moon, which may have been captured, but probably was formed through an alternate phenomenon).
Jupiter is the largest planet in the solar system.
It, therefore, has a greater gravitational influence (where the influence surpasses the force of the other Planets and the Sun).
Hence, it has the greatest influence for capturing objects in space.
Jupiter has an extraordinary gravitational pull, and this allows it to capture large passing objects that then collide with one another. This forms dozens of smaller ‘moons’.
Moons of Jupiter
Jupiter has 79 known moons; 53 are named whereas the others are waiting their official names.
While all the moons hold scientific inquiry, the first four moons ‘The Galilean Satellites’ are of most interest.
They were first observed in 1610 and gained their name due to the discovery by the Italian astronomer Galileo Galilei.
The biggest moon is called Ganymede and this is actually the ninth largest object in the solar system.
Its diameter is larger than Mercury’s so it could have been its own planet had it not been captured into the orbit of Jupiter.
Lo is another moon of Jupiter which the most volcanically active mass in the solar system. Its covered in Sulfur and due to its elliptical orbit and gravity, 300ft tides rise from the surface.
There is enough heat for volcanic activity due to hot magma.
Another interesting moon of Jupiter is Europa. Contrastingly, it has a water ice surface, and studies indicate that there may be an ocean held beneath.
It is believed that there is 2x the water on Europa than Earth, and due to the existence of life in similar conditions here on earth, it leads to the potential of life on this moon
Why Are Jupiter’s Moons Being Discovered Now?
Jupiter’s moons have been identified and named ever since astronomers started studying the sky and searching for celestial objects.
Telescopes have formed as a formidable apparatus that have enabled many objects, beyond just moons, to be found.
However, it is due to technological advancement, that Digital Cameras have developed to the point in where astronomers can search further and deeper than ever before.
This has enabled us to find moons that are too small to see compared to the average telescope.
One of the most powerful Digital Cameras in the world (only a few Kilometers in size) was able to capture the latest 12 moons. This is why, they were not discovered before 2018.
Why Does Jupiter Have The Most Moons?
Mercury, Venus, Earth and Mars have just three moons between them. This is in direct comparison to 172+ of the Outer Giants.
You may be wondering why there are there so few moons between the first four planets and so many between those distant giants?
This is all down to the difference between Terrestrial and Jovian planets.
The terrestrial planets are Mercury, Venus, Earth and Mars. These are small and compact which are also near the Sun. As such, they are warm when compared to their outer counterparts.
The Jovian planets consist of those beyond the asteroid belt: Jupiter, Saturn, Uranus and Neptune.
These are comparatively massive planets comprised of gas and they’re extremely cold.
They each have many moons and it dates due in part to the formation of our Solar System around four and a half billion years ago.
Everything started out as a massive collection of gas, space, and dust which congregated and collapsed due to the force of gravity.
During the collapse, it heated and rotated forming what is now known as the Protoplanetary Disk.
The terrestrial planets were created when small chunks of metal and rock collided together but remained intact thanks to gravity.
However, many pieces aka planets were destroyed upon impact which is why the terrestrial planets are so relatively tiny.
Only the most massive though still reasonably small of planets could survive the collisions and form the planets we know today.
The further out you go in the Protoplanetary Disk the colder it becomes and it’s out there that small pieces of ice floated around along with the metal and rock.
When the metal rock and ice collided, they also created small planets but because collisions weren’t as frequent, they were able to grow much larger than the terrestrial planets.
These massive collections of rock metal and ice then enacted their own gravitational pull which attracted massive clouds of gas floating around in the disk, forming the gas and ice giants.
While all of this was happening the metal rock and ice continued to collide together to form other smaller planets which were sucked into the orbit of these giant planets.
This is a reason why they have so many moons.
This supports and coincides with other theories on the creation and collection of moons, like the Capture Theory (whereby large planets like Jupiter are so massive that they collect passing satellites and hooks them into orbit due to the intense force of its gravity).
So, there does not always need to be massive crashes and high-speed deflections – just something formed elsewhere that becomes attracted and puled into any given planet.
This also helps to explain why Mars has two moons. It is the closest to the asteroid belt so its gravitational pull has enabled it two acquire the two moons which we now know Phobos and Deimos.
The Role of the Sun
Another factor to consider in the role of the Sun in the Solar System.
The Sun is so massive that it can easily attract and capture passing satellites. This is likely why the planets closest to it (Mercury and Venus) have no moons. They cannot overpower the Suns gravitational pull.
The Sun’s gravitational pull weakens the further out you go. This explains why Jupiter and the Jovian planets were able to collect so many moons.
Beyond this, the Giant’s gravity is considerably stronger than the terrestrial planets (due to their size) so this combination allows them to collect passing satellites which in turn become moons.
- Why Does Saturn Have So Many Moons? [& What Are They Like?]
- Which Planets Do Not Have Moons [Why & What This Means!]
Hey, my name is Chris. I’m a passionate and seasoned astronomer who loves nothing more than observing the night sky. I also love researching, learning, and writing all things Space and the Universe. I created Astronomy Scope to share my knowledge, experience, suggestions, and recommendations of what I have learned along the way while helping anyone to get into and maximize their enjoyment of the hobby.