Saturn is the hipster of our solar system. The second largest planet, its flashy rings make it the cooler cousin to the lumbering gas giant Jupiter or to the sizzling Venus. Saturn is visible with the naked eye from Earth—though its rings, discovered in 1610 by Galileo, are not. Sixty-five years later, in 1675, Italian-born French astronomer Giovanni Domenico Cassini noted that the rings were separate from each other. His namesake orbiter, Cassini, was launched in 1997 by NASA to reveal the ringed giant in all its glory, as we have never seen it before.
Unraveling the Rings
Saturn boasts the most extensive ring system in our solar system, and NASA says this is the highest-resolution color image of any part of Saturn’s rings ever made. The natural color image, which is created from two photos, shows a portion of the inner-central part of the planet’s B Ring.
NASA says it remains unclear exactly what “causes the variable brightness of these ringlets and bands—the basic brightness of the ring particles themselves, shadowing on their surfaces, their absolute abundance, and how densely the particles are packed, may all play a role.”
Soft Swirls Seen by Cassini
From 700,000 miles above the planet’s surface, the orbiter Cassini photographed subtle, multi-hued bands of swirling clouds in Saturn’s northern hemisphere at the end of August 2017. “This view looks toward the terminator—the dividing line between night and day—at lower left. The sun shines at low angles along this boundary, in places highlighting vertical structure in the clouds. Some vertical relief is apparent in this view, with higher clouds casting shadows over those at lower altitude,” NASA explains.
A Stormy North Pole
Cassini captured this view of turbulent clouds on Saturn’s north pole from about 166,000 miles above the surface. It was taken on April 26, 2017, the day the spacecraft first dove through the gap between the planet and its rings.
In 2017, Cassini plunged into the planet’s surface, ending its 13-year tour of Saturn. NPR recently stitched together thousands of its photos into one very cool video, to pay tribute to Cassini for its hard work before its demise.
In False Color, as Seen by Voyager 1
Voyager 1 was launched by NASA in 1977 to explore the outer reaches of our solar system. It flew by Saturn in 1980, coming within 77,000 miles of the ringed planet’s top atmosphere. Voyager revealed the complex structure of Saturn’s rings. The rings, which surround Saturn at its equator, don’t touch the planet. There are seven rings made up of thousands of narrow ringlets. The ringlets are made up of billions of pieces of ice. However, the rings won’t last forever. In December 2018, NASA announced that the rings could disappear in the next 100 to 300 million years.
Eclipsing the Sun
This image, assembled by composites taken by the Cassini orbiter, shows Saturn and the sun in a moment of eclipse. The Cassini orbiter, part of the Cassini-Huygens mission, is a joint NASA/ESA/ASI robotic spacecraft mission sent to study Saturn and its satellites. It consists of the orbiter and the European Space Agency-developed Huygens probe. This is named for famed Dutch astronomer Christiaan Huygens, who in 1655 became the first person to describe Saturn’s rings as disks encircling the planet.
Strange Hexagon
Most experts agree that Saturn is a giant ball of gas without a solid surface, though it does appear to have a hot inner core of iron and rock. Partially due to this, Saturn has flat poles and bulges at the equator. As the planet approaches summer, jet streams circulate to create vortexes similar to hurricanes on Earth.
Cassini’s camera revealed a hexagon-shaped vortex above the planet’s northern hemisphere that circulates hundreds of miles above in the stratosphere layer.
“The edges of this newly-found vortex appear to be hexagonal, precisely matching a famous and bizarre hexagonal cloud pattern we see deeper down in Saturn’s atmosphere,” said Leigh Fletcher, senior research fellow in planetary science at the University of Leicester, U.K. “While we did expect to see a vortex of some kind at Saturn’s north pole as it grew warmer, its shape is really surprising. Either a hexagon has spawned spontaneously and identically at two different altitudes, one lower in the clouds and one high in the stratosphere, or the hexagon is in fact a towering structure spanning a vertical range of several hundred kilometers.”
Polar Vortex, 2004
This image is a compilation of photos taken by the W.M. Keck Observatory in Mauna Kea, Hawai’i. The black square in the lower right side represents missing data. Only the presence of a jet stream is known to exist on the south pole, unlike Saturn’s hexagonal north pole—which some experts say might be the result of a novel aurora.
Hubble’s Latest Portrait
Saturn’s latest portrait was taken by Hubble as part of the Outer Planet Atmospheres Legacy project (OPAL), organized by scientists studying the gas giant planets of our solar system.
Saturn’s appearance changes with its seasons, caused by the planet’s 27-degree axial tilt. This image was taken during summer in the planet’s northern hemisphere.
Bizarre Temperatures on Moon Mimas
One of Saturn’s small inner moons, Mimas, or Saturn I, was discovered in 1789 by astronomer William Herschel. Named after one of the Titans in Greek mythology, it exhibits a bizarre pattern of daytime temperatures. As Cassini illustrates, it has a distinct warm side on the left, as well as a sharply cold side on the right. There is an unexplained V-shaped boundary in between.
Surface of the Moon of Enceladus
This is an artist’s rendering of the surface of Enceladus, the sixth largest moon of Saturn. Known for its extensive water ice on the surface, it’s about one-tenth the size of Titan, Saturn’s largest moon. Cassini identified a water-rich plume, which spouts from the moon’s south polar region. It’s known to be extremely geologically active.
What Will We Learn Next?
NASA plans to to send a unique spacecraft to Titan, one of Saturn’s moons with an atmosphere four times denser than Earth’s and low gravity. A dual-rotor quadcopter called Dragonfly will buzz over Titan but also land on the moon to collect samples of water and organic molecules. NASA explained in 2019 that “the rotorcraft will fly to dozens of promising locations on Titan looking for prebiotic chemical processes common on both Titan and Earth.”
Named for its eight insect-like rotors, Dragonfly will launch in 2026 with an expected ETA of 2034.
Why Space Matters to Treehugger
Space is our planet’s home and its wonders help us get outside and foster an appreciation of nature. Exploring space and the cosmos can also help us learn about what’s happening on Earth. Space-based technologies have helped us better understand climate change, water cycles, and even air quality.
