Exploring planet Saturn and its elegant rings

Saturn and its rings

Let us learn some more about this deceptively calm and elegant planet, Saturn.

“The Saturn system is a rich planetary system. It offers mystery, scientific insight, and obviously splendor beyond compare, and the investigation of this system has enormous cosmic reach… just studying the rings alone, we stand to learn a lot about the discs of stars and gas that we call the spiral galaxies”

-Carolyn Porco

A survey was taken by ranker to rank the planets in the solar system. It was clear how much people loved Saturn as Saturn ranked to on position two after Earth (of course we won’t stop loving our home planet right?).

Saturn is for sure the most dazzling planet in the solar system. Its bright yellowish-brown surface and the most extensive ring system contributes to its distinctive nature.

History…

Saturn has been fascinating scientists and amateur astronomers for thousands of years. Saturn is known since prehistoric time the only reason being that it is visible to the naked eye. In ancient Greek, the planet was called Phainon, and in the Roman times, it was called the Star of Saturn.

Saturn means the God of agriculture. This modern name comes from Phainon who according to Roman mythology was sacred to be the agricultural God.

In Hindu astrology, planet Saturn is one of the Navagrahas (Nava – nine. Grahas – planets. Navagrahas – nine planets) and is called Shani and judges everyone based on their good and bad deeds.

Though the planet is visible to the naked eye, its rings, however, need some eye aiding device. To see Saturn, the requirement is having a least of 15mm diameter lens.

17th century, scientists like Galileo Galilei, Christiaan Huygens, and Giovanni Cassini took a closer look at the planet and discovered its planetary rank along with many of its moons and rings.

About…

The planet Saturn, like its other siblings, leaves no chance in surprising us.

Saturn and its rings

It’s the sixth planet from the Sun, third last. Saturn is the 2nd largest planet in the solar system after Jupiter. But how large exactly? Well, it’s about 10 times wide as Earth. It takes Saturn 29.457 earth years to complete it’s one year (Saturnian year).

Here is the weird part. When compared, the equatorial radius and the polar radius of the planet, it was seen that they differ by 10%. Equatorial radius – 60,268 km (37,449 mi) and the polar radius – 54,364 km (33,780 mi).

This creates a difference of 5,904 km (3,668 mi) in its polar and equatorial radii which is extreme as compared to the 21 km (13 mi) difference of Earth’s polar and equatorial radii.

But despite all the size, Saturn is composed of mainly hydrogen and helium, this makes it the least dense planet, in fact, it’s the only planet that’s less dense than water, 30% less dense. This means that if we could place the planet in an enormous water body, then the planet will float!

Ok, now admit it, we all have dreamt about experiencing the sky being on Saturn right? But that’s a little difficult. Because of the gaseous composition of the planet, it does not have a true surface (I am sad too).

It’s time for some wonderful sightseeing…

A few decades after the discovery of infrared light came the infrared astronomy in 1830.

To know more about the different methods of observation check out astronomical instrumentation.

The infrared view of Saturn will take you to the seventh heaven.

Saturn in infrared
infrared view of Saturn
Image credit: NASA/JPL/ASI/University of Arizona

The planet has superhot interiors. In case you wonder how hot, it goes up to 11,700 degrees Celsius (21,092 degrees Fahrenheit). Guess how hot that is? Exactly, that’s twice as hot as the surface of the sun.

Saturn's temperature compared to Earth and Sun

That said, the planet radiates 2.5 times more energy into space then it receives from the sun (amazing in it?).

Since the interiors are so hot, in regions where the planet doesn’t receive sunlight at all, called the night side of the planet, Saturn lights up its own thermal radiation.

Density…

The planet, despite being so huge, doesn’t stand a chance in competing with Earth in density with 1/8th the average density of Earth. Wanna see the numbers? The density of Earth – 5.514 g/cm3 and the density of Saturn – 0.687 g/cm3.

But don’t take the planet for granted, despite the extremely low density the planet has the mass of 95 Earths! Now that’s massive. This happens because of the planet’s enormous size.

Visits…

Till now, the planet has seen 4 visits. These were made by Pioneer 11 in 1979, Voyager 1 in 1980, Voyager 2 in 1981 and Cassini in 2004.

Cassini spacecraft
Cassini

While Pioneer 11, Voyager 1 and Voyager 2 made a flyby, Cassini orbited the planet from 2004 – 2017. It also deployed a probe by the name Huygens into the atmosphere of Titan (Saturn’s moon) in 2005.

Do you want to visit Saturn?

umn.. its a bit difficult of course, but you can see what happens as you enter Saturn’s atmosphere in this video.

Composition…

Models suggest that the core of the planet is made up of iron, rock, and nickel.

composition of planet Saturn
KelvinsongSaturn diagramCC BY-SA 3.0

The very next layer is made up of metallic hydrogen.

The middle layer is made up of liquid helium – saturated molecular hydrogen. This liquid layer gradually transits to a gaseous state with increasing altitudes.

The final outer layer is 1000 km long and is made up of gasses, liquids and ammonia crystals.

Storms…

The contents in the Saturns uppermost layer swirl the planet completely giving it a golden cloudy look and with it some STORMS!

Yes, storms!

Though our dear planet, Saturn appears to be very calm, it’s super active.

The winds on Saturn can take the speed of up to 18,000 km/h. Ranks 2nd in the solar system for the wind speed. Guess who’s the first… Neptune!

Great white spot…

Great White spot of Saturn
image credit – NASA

Also called the great white oval, is a short-lived phenomenon that occurs on Saturn once every Saturnian year. This storm extends for thousands of km and is so huge that it is visible from the earth when viewed by a telescope.

It is viewed a lot of time by astronomers. Asaph Hall in 1876 observed the great white spot and determined Saturn’s period of rotation.

And you know what’s really interesting?

The next great white storm is expected in 2020! Excited already?

On the poles, the storms are permanent. They remain fixed on the poles and don’t move unlike the storms on Earth that drift continuously.

The North Pole has some weird facts for you.

It has a near-perfect hexagon-shaped storm that rotates with the planet without changing longitude.

north pole of Saturn
the north pole of planet Saturn

Each of the sides of the hexagon is 13,800 km (8,600 mi) long. No one knows why it is like that.

In 2006, Cassini observed a storm on the South Pole that had a clear eyewall. Now you may think what’s weird about that. Well, eyewalls are common on storms seen on earth only. Storms with an eyewall were never seen before on any planet other than earth.

Just like on earth, storms on Saturn also produce lightning but the intensity is 1000 times more than the lightning produced on earth.

Moons…

Just like the extensive rings of Saturn, the moons too spread far from their home planet.

moons of Saturn

They range in size from small moonlets that have a diameter of less than 1 km to large moons like titan which surpasses the diameter of mercury.

The planet has a total of 62 moons with confirmed orbits. Only 13 moons have diameters larger than 50 km and just 7 moons are large enough to be ellipsoidal in shape and only two of those moons, Titan and Rhea are in hydrostatic equilibrium.

We can divide Saturn’s moon into 10 groups

Let’s look at them one by one.

Ring Moonlets…

These moons orbit the home planet while staying within the vicinity of the rings. Now because these moonlets have to traverse their path through the rings, they create gaps in the ring. This effect is called Propeller. It occurs only if the moonlet is large enough.

For example, the moonlet S/2019 S 1 in the B ring, estimated to be 300 meters in diameter does not induce a propeller. The reason behind this is assumed to be the high density of ring B.

Pan and Daphnis fall in the A ring and are large enough to clear continuous gaps in the ring (these moons don’t fall in the ‘ring moonlets’ group).

In 2007, 150 moonlets were discovered. This discovery showed they were confined in three very narrow bands in the A ring. These were between 126,750 and 132,000 km away from Saturn’s center. Each band is about 1000 km (621.37 mi) long.

The other areas in the A ring stay undisturbed. Studies on the A ring have estimated that the ring has about 7,000 – 8,000 propellers that are larger than 0.8 km (0.49 mi) in size and millions that are larger than 0.25 km (0.155 mi) in size.

These moonlets are thought to be the result of the breaking up of the larger satellites of Saturn.

Similar types of Moonlets are seen in the F ring.

Ring shepherds…

This group consists of those satellites that are in orbit within or just beyond the planet’s ring system.

These moons are large enough to create gaps in the rings and give them the propeller effect.

These moons are also responsible for giving sharp edges to the ring.

Pan (in the Encke gap)
Daphnis (in the Keeler gap)
Atlas (in the A ring)
Prometheus (in F ring)
Pandora (in F ring)

Are the shepherd moons of Saturn.

These are thought to be the result of the accumulation of powdery particles of the ring.

Co-orbitals…

Janus and Epimetheus are the co-orbital moons of Saturn. And do you know why they are called co-orbitals?

They share the same orbital path across Saturn with a difference of just a few km in their semi-major axis.

Then you may also ask, why don’t they both collide with each other. So the reason is, when they fly past each other, their gravitational interaction causes them to swap their orbits. This happens every 4 years.

Inner large moons…

These are the large moons that orbit within the E ring.

Mimas. Smallest and the least massive of all the inner round moons
Enceladus. This is one of the smallest spherical moons of Saturn.
Tethys. Third largest inner moon.
Dione. Second largest inner moon after the geologically dead moon, Rhea.

Dione
Dione
Image credit – NASA

Alkyonides…

These moons orbit with the inner large moons in the E ring, i.e. between Mimas and Enceladus. Named after the Alkyonides (Greek mythology).

Methone
Anthe
Pallene

These moons fall in the smallest moon category of Saturn.

Trojan moons…

This is one feature that is exclusive of our lovely Saturnian system.

A Trojan body orbits a much larger object, say a planet or a large moon at either the leading L4 or trailing L5 Lagrange point.

Ever heard anything like… moons of moons?

Tethys, the inner large moon of Saturn has 2 trojan moons, Telesto (leading) and Calypso (Trailing).

Dione, also an inner large moon has 2 trojan moons, Helene (leading) which is undoubtedly the largest Trojan moon and Polydeuces (trailing) which has a chaotic orbit and is the smallest.

Outer large moons…

These moons orbit beyond the E ring.

Rhea. The 2nd largest moon of Saturn.
Titan. The largest moon of Saturn, 2nd largest moon in the solar system with a diameter of 5,149 km (3,199 mi).
Hyperion. The closest neighbor to Titan. Titan and Hyperion are locked in a 4:3 mean – motion resonance. And do you know what it means? It means that when Titan makes 4 revolutions around Saturn, Hyperion makes exactly revolution.
Lapetus. 3rd largest of Saturn’s large moons and undoubtedly the most distant of the large moons orbiting the home planet at 3.5 million km (2174799.173 mi).

Moon Titan
Titan

Irregular moons…

These moons are very small and have a large orbital radius. They show inclination and some of them have retrograde orbits. an assumption is that the satellites are wanderers that were captured by the planet’s gravity.

The exact size and the albedo of these moons become very difficult to determine mainly because they are very small to be even resolved by a telescope.

There are three groups in which these moons can be classified.

Inuit group…

This group consists of 5 outer moons that are in prograde motion. They are all similar enough in the distances from the planet.

Orbital inclination – 45 degrees to 50 degrees.
Exhibit a similar color.
These are:- Ljiraq, Kiviuq, Paaliaq, Siarnag and Tarqeq.

Gallic group…

Four prograde outer moons.

Similar distance from the planet.
Orbital inclination – 35 degrees to 40 degrees.
Exhibits a similar color.
These are –Albiorix, Bebhionn, Erriapus, and Tarvos.

Norse group…

29 retrograde outer moons.

These are:-
Aegir, Bergelmir, Bestla, Farbauti, Fenrir, Fornjot, Greip, Hati, Hyrrokkin, Jarnsaxa, Kari, Loge, Mundilfari, Narvi, Phoebe, Skathi, Skoll, Surtur, Suttungr, Thrymr, Ymir, S/2004 S 7, S/2004 S 12, S/2004 S 13, S/2004 S 17, S/2006 S 1, S/2006 S 3, S/2007 S 2, and S/2007 S 3.

Rings…

rings of Saturn

Saturn has one of the most extensive ring systems in the solar system.

These set as the main attraction of the planet.

Naming is done after the alphabet. Not in order though!

Starting from the innermost ring, let us take a look at all the elegant rings of the planet.

D ring…

The innermost ring of Saturn. This ring is very faint as compared to the other rings. It starts at 66,900 km and ends at 74,510 km from Saturn’s center. Width is 7,500 km.

Here is the interesting part. Voyager 1 in 1980, discovered 3 ringlets within the D ring. These were named D73, D72, and D68 (D68 is the closest to Saturn). After approximately 25 years Cassini images revealed that the D72 ringlet remarkably grew in size and moved towards the planet by about 200 km.

C ring…

It starts at 74,658 km and ends at 92,000 km from the planet’s center with a width of 17,500 km.

The ring is very wide as compared to the previous ring. It comes after the D ring. Though not as faint as the D ring, this ring is still fainter in comparison to the other rings.

The ring was discovered in 1850 by William and George Bond. The mass of the ring is estimated to be 1.1*10^18 kg.

Fun fact – the vertical thickness of this ring is just 5 meters!

The ring has two gaps – the Colombo gap and the Maxwell gap.

The Colombo gap…

This gap falls in the inner side of the C ring. This gap contains a bright Colombo ringlet, also called as the Titan ringlet.

Maxwell gap…

This gap finds its place in the outer part of the ring and just like the Colombo gap, it contains a ringlet called the Maxwell ringlet. This ringlet, unlike the Titan ringlet, is dense and non – circular.

B ring…

With a width of 25,500 km, this ring is certainly the largest of all the rings. Along with that, it’s also the brightest of all.

The ring starts at a distance of 92,000 km and ends at 117,580 km from the center of Saturn.

The thickness of the ring ranges from 5 m to 15 m. An unexplained thing about the ring is that it varies greatly in brightness and density.

Cassini division…

This division begins right at the point where the B ring ends, i.e. at 117,580 km and ends at 122,170 km.

With a width of 4,700 km this ring sets as a divider between the B ring and the A ring. Named after the person who discovered the ring in 1675, Giovanni Cassini at the Paris Observatory.

And just like the C ring, this division also has a gap.

Huygens Gap…

It starts at the very beginning of the Cassini Division at a distance of 117,680 km from the planet’s center. This gap contains the very dense and eccentric Huygens Ringlets located in the middle.

A ring…

It comes immediately after the Cassini division at a distance of 122,170 km and ends at 136,775 km from the planet’s center.

At the end of this ring, orbits a small moon, Atlas. Width – 14,600 km.

It has two main gaps, the Encke Gap and the Keeler Gap.

Encke Gap…

Distance from the center – 133,589 km. Width – 325 km.

The gap was discovered by James Edward Keeler who named it in the honor of Johann Encke.

The cause of this gap is the moon Pan that orbits in the gap.

Keeler Gap…

Distance from the center – 136,505 km. Width – 42 km.

Discovered by Voyager 1 and named in the honor of astronomer James Edward Keeler. Caused by the moon Daphnis.

Roche Division…

Distance from the center – 136,775 km. Width – 2,600 km.

The division separates the A and the F ring. Named in the honor of the French physicist Edouard Roche.

F ring…

Distance from the center – 140,180 km. Width – 30 to 500 km.

It is the outermost discrete ring. And don’t you underestimate the ring for its little size because the ring is one of the most active rings in the Solar System.

Remember Prometheus and Pandora? Yes exactly, the two shepherd moons of Saturn. Prometheus orbits inside the ring and Pandora orbits outside the ring.

Discovered by the Pioneer II imaging team.

Magnetosphere…

Saturn’s magnetic field is strong enough to deflect the Solar winds.

Oh, and yes, of course, the planet has auroras.

The disturbances in the magnetosphere due to the solar winds get strong enough to alter the trajectories of the charged particles (in both, the solar wind and the magnetospheric plasma). This process causes the auroras Earth, the same follows on Saturn.

The auroras on Saturn get brighter, moving towards the pole as the solar wind pressure increases.

Here on Earth, the auroras are produced mostly due to Oxygen and Nitrogen molecules but on Saturn the case is different. There the production of auroras is due to hydrogen.

Conclusion…

Saturn is the 6th planet from the sun and the 2nd largest planet in the solar system.

The planet is composed of mainly hydrogen and helium.

It has the lowest density and the most extensive ring system in the solar system.

The planet has a total of 62 moons with confirmed orbits.

Titan is the largest moon of Saturn and the second-largest moon in the solar system.

sahil asolkar

Sahil Asolkar

writer and co-founder

Sahil Asolkar is a writer, poet, and shows a good interest in astronomy. His work can be seen in the articles he writes for Astronomiac.

Similar Posts:

1 thought on “Exploring planet Saturn and its elegant rings”

  1. Underwear lover99

    Really great content.. Everything was compiled almost perfectly and it was really easy to read and understand… I hope you will continue to make this type of content in the future

Leave a Comment

Your email address will not be published. Required fields are marked *