Saturn might be best known as the planet with the rings. But, while the gas giant’s claim to fame is well-deserved in that regard, the rings aren’t Saturn’s only outstanding feature.
The sixth planet from the sun boasts the most moons in the solar system. This article will answer the question of how many moons Saturn has and reveal some fascinating facts about those celestial bodies.
The Number of Saturn’s Moons
Looking at the inner solar system planets, we might think that determining the number of moons orbiting each planet is relatively straightforward. However, Mercury and Venus have no natural satellites. Earth has one, and Mars has two.
However, observation and moon counting start getting more complex as we move further into the territory of gas giants.
Massive planets like Jupiter and Saturn are visible from Earth, but their moons, in most cases, aren’t. In fact, we didn’t know about the four so-called Galilean moons of Jupiter until the early 1600s, when Galilei observed them with a telescope. This is quite a revealing fact considering that one of those moons, Ganymede, surpasses Mercury in size.
It should be noted that Jupiter is much closer to Earth than Saturn. That’s why it is no surprise that Saturn’s moons weren’t observed until decades after Galilei. Yet, the first discovery in that age was that Saturn had moons, but nothing more could be said about them at the time.
The first moons of Saturn were properly viewed and named as recently as the mid-19th century. At first, eight were counted, but that number increased to 14 not long after.
It took over a century to get a clearer picture of the satellites orbiting Saturn. The technological advancements of the modern age helped shine a light on the distant worlds, and, naturally, the number of observed Saturn’s moons went up.
So, how many moons does Saturn have?
The answer is 53 confirmed and 29 provisional moons, totaling 82 possible moons. For clarification, confirmed moons are satellites viewed and confirmed by subsequent observations. On the other hand, provisional moons are those which have been discovered but aren’t yet confirmed.
The provisional moons put Saturn in the No. 1 spot regarding the number of moons. While Jupiter and Saturn have the same number of confirmed natural satellites, the ring planet has three more provisional moons.
Of course, those numbers aren’t set in stone. As space observation technology progresses, more moons will likely be discovered around both planets. But, for now, we can explore the known moons of Saturn in more detail.
Classification of Saturn’s Moons
Based on their location and traits, Saturn’s moons can be classified into 10 groups:
- Ring moonlets
- Ring shepherds
- Co-orbitals
- Inner large
- Outer large
- Alkyonides
- Trojan
- Inuit
- Gallic
- Norse
While these groups have many interesting facts, the inner and outer large groups are fascinating. That’s why we’ll look at those two groups first.
Inner Large Group
The moons of the large inner group are located within Saturn’s E ring. This group includes four satellites: Tethys, Dione, Mimas, and Enceladus.
Mimas and Enceladus are particularly interesting. Mimas is the smallest known round moon in the solar system – even smaller than some irregular satellites orbiting other planets. In fact, the moon has a smaller surface area than California.
Despite being tiny, Mimas was demonstrably able to withstand a massive amount of damage. The proof of the moon’s resilience lies in the Herschel crater, whose diameter measures over 80 miles, compared with the 246-mile diameter of Mimas itself. Placed to scale on Earth, this crater would cover more surface than Australia.
Enceladus is not much bigger than Mimas and, like its group co-inhabitant, holds a unique spot in the solar system: Enceladus is the smallest known geologically active celestial body. In other words, the moon’s surface is still changing and doing so endogenously, i.e., independent of outer influence.
The moon features distinctive fractures around its unusually warm south pole. These fractures, dubbed “tiger stripes,” can emit dust and water vapor jets. Due to this activity and other factors, Enceladus is covered with a layer of ice, making the satellite extremely bright. Specifically, Enceladus counts among the solar system’s brightest objects.
The other two moons of this group, Tethys and Dione, aren’t as fascinating as their smaller counterparts. However, that doesn’t mean they’re ordinary in any way.
Besides some peculiar geological features, such as the large Odysseus crater on Tethys or Dione’s expansive fractures, these moons are distinctive as some of the largest satellites of Saturn. However, the most interesting fact about Tethys and Dione is that they have unique moons of their own, which will be mentioned once we get to the Trojan moon group.
Outer Large Group
Like the inner, the large outer group consists of four moons. From largest to smallest are Titan, Rhea, Iapetus, and Hyperion. The large outer group orbits Saturn beyond the planet’s E ring.
Titan is the largest moon of Saturn and the second-largest in the solar system after Jupiter’s Ganymede. Similar to Ganymede, Titan counts among the rare planet-like satellites. Compared to our Moon, Titan has 80% more mass and a 50% larger diameter. Furthermore, it’s more massive than Mercury and dwarf planets like Pluto and Ceres.
Unsurprisingly due to its size, Titan was the first discovered moon of Saturn. At the time of its discovery in 1655, only five other satellites had been observed – Earth’s Moon and Jupiter’s four Galilean moons.
However, size isn’t the main distinctive feature of Titan. This satellite is the only known one with a dense atmosphere and stable surface liquid bodies.
In other words, Titan has clouds, rain, wind, and seasons. Additionally, the moon features seas, lakes, and rivers on its surface. Titan is the only object in the solar system with all of these features, apart from Earth.
Other planets like Mars may have polar ice caps and subsurface water, and Jupiter’s moon Europa is covered with thick ice that has vast oceans beneath. But only Titan has stable seas and other bodies of liquid.
The liquid in question isn’t water as we know it. Instead, it’s primarily composed of ethane and methane and rests on the moon’s surface, covered by an ice shell. Actual water might be located beneath that, which is part of the most exciting aspect of Titan.
Titan’s atmosphere and surface liquid mix might be a fertile ground for developing organic compounds. The prebiotic chemistry and conditions remind scientists of those on primordial Earth. This combination could be a foundation for one of the greatest prizes of space exploration: extraterrestrial life.
Of course, compared to the incredible Titan, other outer large group moons aren’t as spectacular. For example, Hyperion is an irregular satellite, while Rhea and Iapetus are distinctive by being among the largest moons of Saturn.
Ring Moonlets and Shepherds
The ring moonlet and shepherd groups are reserved for smaller bodies that count as Saturn’s satellites but not as moons. As the names suggest, these bodies are located within and around the planet’s rings. In addition, there are potentially millions of smaller objects, mainly consisting of residual matter from the larger satellites.
Co-Orbitals
Two of Saturn’s moons hold a special place in the gas giant’s system. These are Janus and Epimetheus, satellites of similar size and orbits.
The orbits of these moons are extremely close. If the satellites were to pass beside one another, they would most likely collide. However, due to the interaction of the gravitational force from both bodies, they do something much more interesting. Every four years, Janus and Epimetheus swap orbits, taking each other’s place.
Alkyonides and Trojan Moons
The Alkyonides group consists of only three moons, Anthe, Methone, and Pallene. These are in orbit between Enceladus and Mimas and are relatively indistinct.
On the other hand, Trojan moons are a phenomenon present exclusively in Saturn’s system. These are essentially moons orbiting other moons. As stated before, Tethys and Dione have Trojan satellites.
Trojan moons function by orbiting a larger body in pairs. One moon is at the L4 Lagrange point, also called the leading, while the other is at L5, known as the trailing point. Both are equally distanced from the larger moon.
The leading Trojan moon of Tethys is Telesto, while the trailing is Calypso. Dione has the largest Trojan moon, Helene, as the leading, and the smallest, Polydeuces, as the trailing.
Inuit, Gallic, and Norse Groups
These three groups consist of moons not named after Greco-Roman deities. Instead, they are grouped according to their distance from Saturn, color, and orbital inclinations.
The Inuit group has eight moons, the Gallic group four (with a potential fifth), and the Norse group is the largest by far, counting 46 moons.
Looking Forward to Saturn’s New Moons
As mentioned, new bodies orbiting Saturn will likely be discovered in the future. The last confirmed moon, Saturn LVIII, was announced in late 2019, which means that the search for additional members of Saturn’s system is far from over.
With new technology, the ringed gas giant might boast an even more comprehensive system than previously thought. Or it could get surpassed by Jupiter in the millennia-long race for the most extensive planetary system in our part of the universe.
Time will tell if Saturn will stay at 83 moons – chances are it won’t.