9 Essential Facts About Saturn

This portrait looking down on Saturn and its rings was created from images obtained by NASA's Cassini spacecraft on October 10, 2013.
This portrait looking down on Saturn and its rings was created from images obtained by NASA's Cassini spacecraft on October 10, 2013.
NASA/JPL-Caltech/Space Science Institute/G. Ugarkovic

Saturn is the planet you always drew in elementary school because without those rings, it's just a circle. But what is Saturn, anyway, and what makes it special to planetary scientists? Now is a good time to find out: On September 15, the scientists who operate the Cassini spacecraft—which they've used to study the gas giant for 13 years—are going to intentionally destroy Cassini by sending it on a crash course with Saturn. The data it will send back before it meets its fiery demise will be priceless.

Mental Floss is going to be inside mission control at NASA's Jet Propulsion Laboratory in Pasadena, California, as the scientists send Cassini on its grand finale mission. We'll have a full dispatch for you. In anticipation, we spoke to Saturn experts to find out what you need to know about the planet before Cassini takes its final plunge.


At 75,000 miles across, Saturn is nearly 10 times larger than Earth and the second-largest planet in the solar system, behind its neighbor, Jupiter. It is called a gas giant, meaning it is really big and made mostly of gas: in this case, hydrogen and helium. The deeper you get into Saturn, the greater the pressure and heat. How bad could it be, you ask? Bad enough that hydrogen exists as a liquid metal near the planet's core. In other words, don't expect astronauts to plant flags down there anytime soon. One Saturn year lasts about 30 Earth years, and one Saturn day is, well …


The spacecraft Cassini has been operating in the Saturnian system for 13 years doing extraordinary science—and yet the length of a day on Saturn remains elusive. Is it 10 hours and 39 minutes, as suggested by data from Voyager 2 in 1981? Or is it 10 hours and 47 minutes, as Cassini data suggested when the spacecraft first arrived at Saturn in 2004? Or is it 10 hours 33 minutes, as later data suggested?

The problem is that Saturn keeps giving new answers. There are no continents spinning around for scientists to set a stopwatch to; cloud orbits are unreliable; and measurements of the planet's radio radiation and magnetic fields have proven equally frustrating. As Cassini completes its final orbits, it is collecting up-close Saturn data that might finally answer the question. No matter the number to be determined, 10 hours and change is a tremendous speed for a planet of Saturn's size to be spinning, and it affects even the planet's shape; its poles are flattened as a result of its rotation.


Visiting space aliens would never confuse Saturn with Earth, though the two planets do have one interesting shared characteristic: both are tilted to similar degrees relative to the equator of the Sun. Earth is tilted at 23.5 degrees; Saturn is tilted at 26.7 degrees. Axial tilt is the reason we experience seasons, and Saturn is no different (though the leaves there don't change color due to a pronounced lack of trees). Saturn experienced summer solstice four months ago, marking its maximum axial tilt toward the Sun and making it midsummer in Saturn's northern hemisphere. It will reach Autumn equinox in May 2025.


After 20 years in space—seven years en route to Saturn and 13 years in orbit around it—the Cassini spacecraft is nearly out of fuel for its thrusters. Rather than enter a permanent orbit around Saturn as an artificial satellite, or sent on an intercept course with Uranus, both risky endeavors, Cassini will burn up like a shooting star when it plunges into the depths of Saturn on September 15. For the past six months, Cassini has been taking daring dives through Saturn's rings in a series of 22 orbits, the last of which will send it on an impact course with the planet. As it speeds into the gas giant, it will return data on the composition of Saturn's atmosphere. Cassini's death mission will protect the moons Enceladus and Titan from contamination by Earth germs. 


"Saturn has these absolutely massive storms once every few decades," says Sarah Hörst, a planetary scientist at Johns Hopkins University, "and we actually got to see one of them happen because we've been there so long." Scientists already knew about the storms from Earth-based observation, but close-up study made possible by Cassini gave new insights on how they work and what they do. "These massive storms actually pull up a lot of material from deeper in the atmosphere—stuff that we can't usually see or measure," she tells Mental Floss. This material consists of gases from deep within the planet's atmosphere. Saturn's storms cause dramatic temperature changes, and even have lightning. "If you were somehow managing to stand inside of Saturn's atmosphere, some of the storms would feel quite familiar, and some of these longer-lived storms, these vortexes, are somewhat related to a hurricane."


Saturn has a rocky core surrounded by liquid metallic hydrogen, though the finer details of the planet's interior remain elusive. At Jupiter, NASA's Juno mission is hard at work determining the nature of that planet's core. The 22 proximal orbits of Cassini's "grand finale" have a configuration similar to those of Juno, and scientists hope that data from these orbits can be used with Juno data to learn more about Saturn's interior. "The general picture that there's rocky stuff down there, probably metallic hydrogen, isn't really going to change," says Hörst. "The details of exactly how it looks and where its phase changes are—those types of things—will hopefully be worked out a bit more before Cassini ends."


When the skies are conducive to viewing, even a modest telescope can allow you to see Saturn. It will look just like you imagine: a ball surrounded by a distinctive ring structure. It will even "feel" three dimensional (because it is, of course) in a way that Jupiter or Mars will not. Your telescope might even allow you to spot Titan, Saturn's largest moon. Sky & Telescope offers a guide to help you see Saturn in all its glory.


Earth's moon is about 4.5 billion years old. Saturn's moons are mere infants in comparison: possibly as young as 100 million years old. Matija Cuk, a research scientist at SETI, modeled the orbital evolution of the Saturn system, and found that the orbital shifts of the moons over time, and the gravitational influences of the moons over each other, suggest origins when dinosaurs ruled the Earth. "If calculations predict that something happened in the past and you don't see it, maybe it never happened," he tells Mental Floss. One scenario sees a different inner moon system whose orbits resonated and eventually crossed, causing the moons to collide. The current system of moons then assembled from the debris.

Those rings around Saturn might not be very old, either, and might be related to the young moons. "The rings might be pieces of broken up moons," he says. "You figure out how old the rings are and you can figure out the last time the moons were broken up and when some of them were put back together."


Enceladus, one of Saturn's moons, possesses a global saltwater ocean surrounded by an icy crust. That ocean is in direct contact with a rocky core. Saltwater touching rock is exciting because it allows for interesting chemistry—including the sort that might be conducive to life. Adding to the excitement are hydrothermal vents on the sea floor, spewing water, minerals, and nutrients heated by geothermal activity. Better yet, that ocean is being blasted into space through massive geysers. This means NASA can get to the water, sample it, and hopefully, find life.

Titan, another moon of Saturn, also possesses the right stuff for life—and not boring old liquid water life, either, but something wholly alien: a methane-based life form. Key to such life would be the presence of the molecule acrylonitrile, now known to exist on Titan. The European Space Agency landed the Huygens probe on Titan in 2005, and Cassini later discovered several massive liquid methane lakes on that world. The next step is to send a submarine there and get to work.

The Orionid Meteor Shower Peaks This Weekend


October is always a great month for skywatching. If you missed the Draconids, the first meteor shower of the month, don't despair: the Orionids peak this weekend. If you've ever wanted to get into skywatching, this is your chance.

The Orionids is the second of two meteor showers caused by the debris field left by the comet Halley. (The other is the Eta Aquarids, which appear in May.) The showers are named for the constellation Orion, from which they seem to originate.

The shower is expected to peak overnight from Sunday, October 21, to Monday, October 22, when you can plan to see 15 to 20 super-fast meteors per hour. The best time for viewing is between 2 a.m. and 5 a.m., when Orion appears completely above the horizon. Make a late-night picnic of the occasion, because it takes about an hour for your eyes to adjust to the darkness. Bring a blanket and a bottle of wine, lay out and take in the open skies, and let nature do the rest.

There's a chance that the Moon might interfere with the meteors' visibility, according to Space.com. Leading up to its full state on October 24, the Moon will be in a waxing gibbous phase, becoming larger and brighter in the sky as the Orionids speed past Earth. Limiting light pollution where you can—such as by avoiding city lights—will help.

If clouds interfere with your Orionids experience, don't fret. There will be another meteor shower, the Leonids, in November, and the greatest of them all in December: the Geminids.

A version of this story appeared in 2017.

How the Hubble Space Telescope Helped the Fight Against Breast Cancer

NASA, Getty Images
NASA, Getty Images

The beauty of scientific research is that scientists never really know where a particular development might lead. Research on Gila monster venom has led to the invention of medication that helps manage type 2 diabetes, and enzymes discovered in the hot springs of Yellowstone National Park are now widely used for DNA replication, a technique used by forensic scientists to analyze crime scenes.

The same rule of thumb applies to NASA scientists, whose work has found dozens of applications outside of space exploration—especially in medicine.

Take the Hubble Space Telescope. Launched in 1990, the Hubble has graced us with stunning, intimate photographs of our solar system. But it wasn't always that way—when the telescope was launched, the first images beamed back to earth were awfully fuzzy. The image processing techniques NASA created to solve this problem not only sharpened Hubble's photos, but also had an unexpected benefit: Making mammograms more accurate.

As NASA reports, "When applied to mammograms, software techniques developed to increase the dynamic range and spatial resolution of Hubble's initially blurry images allowed doctors to spot smaller calcifications than they could before, leading to earlier detection and treatment."

That's because the Hubble Space Telescope contains a technology called Charge-Coupled Devices, or CCDs, which are basically electron-trapping gizmos capable of digitizing beams of light. Today, CCDs allow "doctors to analyze the tissue by stereotactic biopsy, which requires a needle rather than surgery," NASA says [PDF]. Back in 1994, NASA predicted that this advancement could reduce national health care costs by approximately $1 billion every year.

And that's just one of the tools NASA has developed that's now being used to fight breast cancer. When cancer researcher Dr. Susan Love was having trouble studying breast ducts—where breast cancer often originates—she turned to research coming out of NASA's Jet Propulsion Laboratory. As Rosalie Chan reports for the Daily Beast, the Jet Propulsion Lab has dedicated vast resources to avoiding the spread of earthly contaminants in space, and its research has included the development of a genomic sequencing technology that is "clean and able to analyze microscopic levels of biomass." As Dr. Love discovered, the same technology is a fantastic way to test for cancer-linked microorganisms in breast duct tissue.

A second technology developed at NASA's Jet Propulsion Laboratory—the Quantum Well Infrared Photodetector, or QWIP—enables humans to see invisible infrared light in a spectrum of colors, helping scientists discover caves on Mars and study volcanic emissions here on Earth. But it's also useful at the doctor's office: A QWIP medical sensor can detect tiny changes in the breast's blood flow—a sign of cancer—extremely early.

And as any doctor will tell you, that's huge: The earlier cancer is detected, the greater a person's chance of survival.