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.

1. SATURN BY THE NUMBERS.

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 …

2. THE LENGTH OF A SATURNIAN DAY IS A MYSTERY.

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.

3. SATURN HAS SEASONS.

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.

4. HERE'S MORE ABOUT CASSINI, NASA'S MOST AMBITIOUS PLANETARY MISSION EVER.

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. 

5. ENJOY TERRIBLE WEATHER? YOU'D LOVE LIFE ON SATURN.

"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."

6. IT HAS A CORE, BUT DETAILS ABOUT IT ARE HAZY.

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."

7. YOU CAN SEE SATURN FROM YOUR BACKYARD.

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.

8. ITS MOONS MIGHT BE YOUNGER THAN SOME DINOSAUR FOSSILS.

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."

9. THERE'S A GOOD CHANCE THAT LIFE EXISTS ON THOSE MOONS.

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.

Did NASA Ever Consider Women for the Mercury, Gemini, or Apollo Programs?

Russell L. Schweickart, Keystone/Getty Images
Russell L. Schweickart, Keystone/Getty Images

C Stuart Hardwick:

Unambiguously, no.

This was not sexism. NASA decided early on, and quite correctly, that early astronauts must all be experienced high-performance jet test pilots. To anyone who understands what the early space program involved, there can be little question that choosing all men was the right call. That's because there were zero women in the country with high-performance test flight experience—which was due to sexism.

You may have heard of the so-called “Mercury 13” or the Women in Space Program, both of which are misleading monikers invented by the press and/or American aviator Jerrie Cobb.

Here’s what happened:

Randy Lovelace’s laboratory tested astronaut candidates to help NASA select the initial seven Mercury astronauts. He later ran Jerrie Cobb through the same Phase I (biomedical) tests (though not through the other tests, as he didn’t have access to equipment owned by the military). Contrary to some reports, Cobb did not test superior to the men overall, but she did test as well overall. And while that should not have been a surprise to anyone, it was in fact a surprise to many.

Lovelace published a paper on the work in which he suggested that women might actually be preferable candidates for space travel since they weigh less on average and consume less oxygen, water, and other consumables, a fact which I exploited in my book, For All Mankind, and I can tell you that on a long duration mission (of several months) the difference really does add up.

This had no effect on Mercury, Gemini, or Apollo, all of which were short little jaunts in which the mass of the astronauts wasn’t terribly critical, and all of which were always going to be flown by high-performance test pilots anyway.

However, it attracted the attention of famed aviation pioneer Jackie Cochran, who agreed to fund further research on the suitability of women for space.

Pioneer American aviator Jacqueline "Jackie" Cochran in the cockpit of a Curtiss P-40 Warhawk fighter plane
Jackie Cochran in the cockpit of a Curtiss P-40 Warhawk fighter plane
Public Domain, Wikimedia Commons

Cochran and Cobb recruited several more women, mostly from the ranks of the Ninety-Nines, a women aviator’s professional organization founded by Amelia Earhart. These women also went through the initial biomedical testing, and 13 passed at the same standard as met by the Mercury astronauts.

So far so good. Cobb, Rhea Hurrle, and Wally Funk went to Oklahoma City for an isolation tank test and psychological evaluations, and Lovelace secured verbal agreement through his contacts to send another group to the Naval School of Aviation Medicine for advanced aeromedical examinations using military equipment and jet aircraft.

However, no one had authorized the use of the military facilities for this purpose—or the costs that it would entail. Since there was no NASA request behind this effort, once Lovelace tried to move forward, the military refused his access.

Meanwhile, Cobb had been enjoying the attention she was receiving and, according to some, had gotten it into her head that all of this was going to lead to some of the women actually flying in space. In fact, I’ve found no evidence that Lovelace ever implied that. This was a small program of scientific study, nothing more. Nevertheless, Cobb flew to Washington, D.C. along with Jane Hart and was given a meeting with then-vice president Lyndon Johnson.

Johnson was congenial—Cobb has always claimed he pledged his support—but immediately afterward, he sent word to have all support for the experiments withdrawn.

Far be it from me to defend the motives of LBJ, but consider this: The president had publicly committed the nation to returning a crew from the moon by the end of the decade—and this was at right about the same time when enough work had been done for Johnson to have a handle on just how hard that was going to be. He may or may not have supported the idea of women astronauts in general—we have no idea—but Jerrie Cobb standing before the press, pushing for “women in space” was definitely, irrefutably a distraction he didn’t need. And any resources devoted to it were being pulled directly away from the moon shot—which, to Johnson, was the goal.

Jerrie Cobb poses next to a Mercury spaceship capsule
Jerrie Cobb poses next to a Mercury spaceship capsule
NASA, Public Domain, Wikimedia Commons

Cobb has always maintained the women were misled and betrayed. I’ve found no evidence of that. Testimony of many of the other participants suggests that Cobb simply got carried away—not that anyone could blame her. Let’s remember that at that time, she couldn’t have known what was really involved in space flight or what the program would look like over the next decade. No one did.

Of course, American women did start flying in space with the Space Shuttle. Do not for a moment think this means they didn’t face the same prejudices at NASA that they did everywhere else. The first class of women astronauts was, according to my sources, invited to help design an in-flight cosmetics kit—an offer they immediately and forcefully shot down. Thirty years later, women remain a distinct minority in the U.S. astronaut corps ...

The bigger question is not whether Cobb was betrayed, but why, in 1961, not a single U.S. woman had been hired to work in high-performance flight test—considering that so many (like Cobb, for example) had performed test flight and ferry duties during the war.

Why weren’t women welcome in the post-war aerospace economy, and why—even today—are so few women granted degrees in engineering of any sort? I don’t know the answer, though sexism is unquestionably in the mix, but it’s a question we need to address as a nation.

This post originally appeared on Quora. Click here to view.

True or False: Was This Object Left on the Moon?

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