Saturn’s Composition: What Lies Beneath the Clouds?

Imagine a colossal swimming pool, one so huge that you could float a planet in it. The Saturn composition is so light and airy that the planet would bob around in your pool. Wouldn’t that be a surprise in your backyard?

The gas giant mainly contains hydrogen and helium. Additionally, it’s the only solar system planet having an average density less than water. So, it’s like an enormous helium balloon. But what’s beneath the clouds?

Let’s look at Saturn’s atmosphere and composition toward its rocky center. That’s where you’ll find a dense core filled with nickel and iron. The metals have a rocky crust built from intense heat and pressure, condensing the core over millennia. Around that is a core similar to Jupiter, where liquid metallic helium flows inside a rolling layer of liquid hydrogen.

Understanding Saturn’s composition is crucial for understanding the solar system’s formation and evolution. It also helps scientists know what to look for in exoplanet research. Studying Saturn’s atmosphere aids in advancing our knowledge of planetary science and astrophysics.

The NASA and CICLOPS images below show Saturn in all her natural beauty, with Earth appearing as a bright dot in the far distance.

Saturn's Composition
Image Credit: NASA and CICLOPS

The Saturn Composition: Layers

Saturn has many cloud layers swirling around the planet in zippy jet streams and intense storminess. We see images of the gassy world in varying shades of gray, brown, and yellow. Yet, the metallic and rocky inner core hides beneath the clouds. Let’s pull it all back to get a closer look.

Saturn Atmosphere: The Gaseous Envelope

Saturn has no actual surface since it mainly contains swirling gases above liquids and its small core. But that doesn’t mean a spacecraft could fly through and efficiently capture data about the fiery world. Instead, Saturn’s composition of wildly extreme temperature and air pressure would likely vaporize any spacecraft trying to fly through.

Instead, scientists learn about the Saturn atmosphere through flybys and probes. As a result, we know that upper atmosphere winds reach 1,600 feet (500 meters) per second near the gas giant’s equator. Compare that to Earth’s hurricane forces that rage at 360 feet (110 meters) per second, and you’ll get a better idea of the intensity of Saturn’s upper atmosphere. We know the damage hurricanes and cyclones cause on Earth, so that we can envision the violence of Saturn’s winds.

In addition, Saturn’s atmospheric pressure is so forceful that gasses squeeze into liquids. That’s like diving deep under the ocean’s surface to incur pressure so powerful that it liquifies everything present. You’d have to dive in the ocean’s deepest parts to come close to the gas giant’s pressure.

The Saturn composition of approximately three-quarters hydrogen and one-quarter helium makes it susceptible to color changes depending on the season. Saturn’s atmosphere also contains traces of methane and water ice.

The Hubble image below comes from September 12, 2021. It shows the northern hemisphere’s color changes in the atmospheric bands during early autumn. The South Pole’s pale blue tint comes from colder clouds in the gas giant’s southern hemisphere winter.

2021 Hubble Telescope image of Saturn
Image Credit: NASA, ESA, A. Simon (Goddard Space Flight Center), M.H. Wong (University of California, Berkeley), and the OPAL team

Saturn’s North Pole

How’s this for an incredible atmospheric feature on Saturn – the north pole has a hexagon-shaped jet stream! Voyager I first saw the six-sided pattern in Saturn’s atmosphere. Later, the Cassini spacecraft gathered more information about this stunning phenomenon.

The hexagon spans about 20,000 miles (30,000 kilometers) wide. A massive storm rotates at the center with 200-mile (322-kilometer) per hour jet streams. Astronomers haven’t found another weather feature quite like this on any other solar system planet.

Saturn’s north pole.
Cassini Image Credit: NASA, JPL, and University of Arizona

The Inner Core

Most of Saturn’s composition comes from hydrogen gas in its atmosphere. However, due to the intense pressures, the gas changes to liquid as you move toward the planet’s center. Scientists find heavier liquid helium beneath the liquid hydrogen.

Further into Saturn’s body are higher pressure levels, so the hydrogen transforms into liquid metallic hydrogen. Then, finally, planetary scientists think the gas giant has a rocky core at its center. A core of about ten times Earth’s mass!

Saturn Atmosphere: Chemical Makeup

Hydrogen and helium dominate the Saturn composition, with 75% of the gas giant made of hydrogen. The remaining 25% helium gas swirls through the atmosphere.

Saturn’s troposphere (the “weather” part of an atmosphere) has three distinct regions of cloud decks. Astronomers predict cloud location based on temperature, where vapor condenses into droplets. Within Saturn’s troposphere, temperatures range from -202 to +176°F (-130 to +80°C.)

  • The top cloud deck is full of ammonia clouds with a temperature near -418°F (-250°C.) It is about 62 miles (100 kilometers) below the troposphere’s highest point (the tropopause.)
  • Next, the middle cloud deck contains ammonium hydrosulphide and lies about 106 miles (170 kilometers) below the tropopause. It has a temperature of around -94°F (-70°C.)
  • Then, the lowest cloud deck, nearest the planet, is made of water clouds. This layer is approximately 81 miles (130 kilometers) below the tropopause. Temperatures here are at water’s freezing point, 32°F (0°C.)

Methods of Saturn Composition Analysis

Researchers use data from the Cassini-Huygens Mission to make critical discoveries about the composition of Saturn. Below, you’ll see how scientists recently concluded Saturn’s ring age using Cassini information. In addition, astronomers use ground-based telescopes like NASA’s IRTF (Infrared Telescope Facility) and the W. M. Keck Observatory in Hawaii to study the planet.

Working together, scientists worldwide help determine the Saturn atmosphere composition. The Cassini Mission launched from Cape Canaveral in October 1997 and was the first spacecraft to orbit Saturn, beginning in July 2004.

During its time near the planet, Cassini and the Huygens probe collected invaluable data about the gas giant’s makeup, rings, and moons. The spacecraft dove between Saturn’s rings in its last months before taking a final dive into the Saturn atmosphere on September 15, 2017. Researchers sent it plunging to crushing vaporization after almost 20 years in space so they could protect worlds like Titan and Enceladus. Although the Saturn composition won’t allow life as we know it, these moons have liquid water oceans beneath their icy crusts. And they just might harbor conditions for life forms.

Artist rendition of Cassini and Saturn.
Illustration Credit: NASA and JPL

Saturn Composition: The Mystery of Saturn’s Rings

Saturn’s rings are mainly water ice with less than a few percent of non-icy materials. The “pollutants” come from micrometeoroids like asteroids or nearby moon fragments smaller than grains of sand. The dusty particles constantly collide with the icy ring particles to increase the space debris that circles Saturn.

The ice particles in the rings range from tiny microns to mountain-sized. Each ring contains billions, and maybe trillions, of these water ice chunks. The rings themselves are about 30 feet (10 meters) wide or thick. They likely formed when one of Saturn’s moons broke up. Or perhaps they started from leftover debris when Saturn’s gravity ripped apart a passing meteor or comet.

Only recently, scientists were still determining how long the bombardment had occurred. Think of it like etching glass, where you use a high-pressure stream of sand to create patterns in glass. And in a somewhat similar way, the dusty particles etch away the icy particles within Saturn’s rings.

The rings and moons of Saturn. 
Illustration Credit: NASA and JPL

Scientists Analyze Saturn’s Rings

Three new studies from California scientists at NASA’s Ames Research Center examine Cassini space mission data to give evidence that Saturn’s rings are much younger than the gassy world itself.

One of the studies shows the arrival rate for non-icy material into the rings, which gives scientists an idea of how much the micrometeroids should have “contaminated” the icy portion of the rings. They determined that the grain-sized meteroids and dust come in slowly, which lets Saturn’s gravity pull them into the rings more effectively. As a result, scientists believe the rings are only a few hundred million years old, compared to Saturn’s 4.6 billion-year lifespan.

Cassini’s measurements from the three studies show that Saturn was likely around 4 billion years old when the rings developed. And while that conclusion is controversial in the astronomy world, the scientists believe their data makes it hard to reach any other possibility. Jeff Cuzzi is an Ames researcher and was the interdisciplinary scientist for Cassini’s Saturn ring exploration. He also co-authored one of the three recent studies.

In basic terms, the scientists propose that Saturn’s rings are young because the micrometeroids and other non-icy contaminates would whittle away the icy components of the rings over time. Since the rings are still mostly ice, there hasn’t been enough time for the pollutants to etch the ice away.

The image below shows a stunning view of Saturn’s rings and even captures the hexagonal storms at the gas giant’s north pole. Together, they are a sight to behold!

Cassini image of Saturn.
Image Credit: NASA, JPL-Caltech, and Space Science Institute