WEBVTT - BrainStuff Classics: Will Saturn's Rings Last Forever?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeartRadio. Hey brain Stuff,

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<v Speaker 1>Lauren Vogelbomb here with another classic episode of the podcast

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<v Speaker 1>for you. In this one, we talk about Saturn's breathtaking rings,

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<v Speaker 1>how they formed, and why we're actually really lucky to

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<v Speaker 1>be around to see them, because they won't exist for

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<v Speaker 1>very long on the cosmic scale.

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<v Speaker 2>Hey brain Stuff, Lauren vogelbomb Here, humanity exists at a

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<v Speaker 2>very special time in our Solar System's history, the era

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<v Speaker 2>of Saturn's rings. In the next one hundred million years,

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<v Speaker 2>Saturn's rings will completely disappear, and planetary scientists have realized

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<v Speaker 2>that it acquired those rings only very recently. During the

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<v Speaker 2>Cassini mission's final months at Saturn, the NASA spacecraft carried

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<v Speaker 2>out a series of daring orbits through the space between

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<v Speaker 2>the planet's cloud tops and innermost edge of its rings.

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<v Speaker 2>This so called Grand Finale signaled that the end was

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<v Speaker 2>nigh for the probe, and on September fifteenth to tenty seventeen,

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<v Speaker 2>it burned up in the gas giant's atmosphere, bringing a

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<v Speaker 2>spectacular thirteen years of science in Saturn's orbit to a

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<v Speaker 2>poignant close. The spacecraft was low on fuel and to

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<v Speaker 2>avoid an accidental crash into one of Saturn's potentially habitable moons.

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<v Speaker 2>NASA had long ago decided that the best way to

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<v Speaker 2>dispose of the mission was to burn it up in

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<v Speaker 2>Saturn's upper atmosphere. The agency wanted to avoid earthly contamination

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<v Speaker 2>on these pristine alien environments. Before its fiery death, however,

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<v Speaker 2>Cassini took unprecedented measurements of the mysterious ring gap region

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<v Speaker 2>to reveal some surprising ring dynamics. Though mission scientists expected

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<v Speaker 2>to detect some wispy elemental gases in this empty region,

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<v Speaker 2>Cassini's particle instrumentation found a smorgas board of elements and

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<v Speaker 2>molecules raining from the rings down to the planet's atmosphere.

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<v Speaker 2>They estimated around ten tons of material that's about nine

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<v Speaker 2>thousand kilos is falling onto Saturn from the rings per second.

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<v Speaker 2>That means that Saturn's rings will eventually disappear and will

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<v Speaker 2>have existed only for a short blip of s Saturn's

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<v Speaker 2>four billion year life span. So far, researchers have used

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<v Speaker 2>Cassini's ring dives to estimate when Saturn acquired its famous rings.

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<v Speaker 2>When Cassini zipped through Saturn's ring plane. Mission managers allowed

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<v Speaker 2>the planet, its rings and moons to gravitationally tug at

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<v Speaker 2>these speeding spacecraft. These extremely slight tugs resulted in tiny

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<v Speaker 2>changes in the probe's trajectory which could be precisely measured.

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<v Speaker 2>Those changes allowed scientists, too, for the first time, make

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<v Speaker 2>a very good measurement of how much mass is holed

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<v Speaker 2>up in Saturn's rings after analyzing the final set of orbits. However,

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<v Speaker 2>the extent to which Cassini's trajectory was deflected initially didn't

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<v Speaker 2>make sense. It didn't match the predictions by theoretical models.

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<v Speaker 2>It turned out the Cassini's motion was being additionally altered

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<v Speaker 2>by massive flows of material at Saturn's equator, inside its

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<v Speaker 2>thick atmosphere about six thousand miles or nearly ten thousand

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<v Speaker 2>kilometers deep. These massive flows are moving about four percent

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<v Speaker 2>slower than the visible upper atmospheric clouds, causing a gravitational

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<v Speaker 2>anomaly that was and predicted Cassini projects. Scientist Linda Spilker

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<v Speaker 2>of NASA's Jet Propulsion Laboratory said in a statement, the

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<v Speaker 2>discovery of deeply rotating layers is a surprising revelation about

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<v Speaker 2>the internal structure of the planet. The question is what

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<v Speaker 2>causes the more rapidly rotating part of the atmosphere to

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<v Speaker 2>go so deep, and what does that tell us about

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<v Speaker 2>Saturn's interior. However, with this anomaly partially explained, scientists were

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<v Speaker 2>free to measure the gravitational influence of Saturn's rings and

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<v Speaker 2>thus measure their mass. The researchers estimate that the total

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<v Speaker 2>mass of Saturn's rings is approximately forty percent that of

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<v Speaker 2>Saturn's moon Mimas. Considering Mimas is two thousand times smaller

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<v Speaker 2>than Earth's moon, there certainly isn't a lot of material

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<v Speaker 2>in Saturn's rings. Scientists had previously relied on density waves

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<v Speaker 2>or ripples through the rings caused by the motion of

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<v Speaker 2>these sixty two moons in Saturn's orbit to estimate ring mass.

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<v Speaker 2>Although these estimates were also low, astronomers have always assumed

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<v Speaker 2>there was some kind of hidden mass in large blocks

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<v Speaker 2>of material that remained unseen. Now, at the precision measurements

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<v Speaker 2>made by Cassini's final orbits, we know that there is

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<v Speaker 2>no hidden mass. The lower the mass of the rings,

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<v Speaker 2>the younger they are, and because they are predominantly made

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<v Speaker 2>of ice, if they were older, the ring material would

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<v Speaker 2>have become contaminated by interplanetary debris, dulling them, and Saturn's rings,

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<v Speaker 2>as we're acutely aware, are beautifully bright. Previous estimates of

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<v Speaker 2>ring age have been far ranging from four point five

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<v Speaker 2>billion years the leftovers of when Saturn itself was forming,

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<v Speaker 2>to a few tens of million years, But with this

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<v Speaker 2>new finding in hand, it looks like the rings are

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<v Speaker 2>very young, formed less than one hundred million years ago

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<v Speaker 2>and perhaps as recently as ten million years ago. Where

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<v Speaker 2>the rings came from remains more of a mystery. It's

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<v Speaker 2>possible that an icy object from the Kuiper Belt or

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<v Speaker 2>an arrant comet became entwined in Saturn's gravitational field and

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<v Speaker 2>succumbed to the planet's powerful tides, was ripped apart and

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<v Speaker 2>eventually ground down to create the banded rings we know

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<v Speaker 2>and love today. Although Saturn's rings will be gone in

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<v Speaker 2>a hundred million years, it doesn't mean that our Solar

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<v Speaker 2>systems ringed planet days are gone forever. If Saturn can

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<v Speaker 2>create them, there's little reason why Jupiter, Neptune, or Uranus

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<v Speaker 2>can't shred and nice the object create another bright ringed planet.

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<v Speaker 2>Display in the distant future.

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<v Speaker 1>Today's episode is based on the article Saturn's Rings will

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<v Speaker 1>exist for just a blippin time on how stuffworks dot Com,

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<v Speaker 1>written by Ian O'Neill. Brain Stuff is production of iHeartRadio

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<v Speaker 1>in partnership with how Stuffworks dot Com and is produced

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<v Speaker 1>by Tyler Klang. Four more podcasts my heart Radio, visit

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