Will Saturn's Rings Last Forever?

Short answer: Nope! As it turns out, Saturn's rings are fairly new, and they'll only be around a while longer. Relatively speaking. Learn how researchers discovered this in today's episode of BrainStuff.

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Episode Transcript

Speaker 1 (00:02):
Welcome to brain Stuff from How Stuff Works, Hey, brain Stuff,
Lauren Vogelbam Here, humanity exists at a very special time
in our Solar System's history, the era of Saturn's rings.
In the next hundred million years, Saturn's rings will completely disappear,
and planetary scientists have realized that it acquired those rings
only very recently. During the Cassini missions final months at Saturn,

(00:26):
the NASA spacecraft carried out a series of daring orbits
through the space between the planet's cloud tops and innermost
edge of its rings. This so called Grand Finale signaled
that the end was nigh for the probe, and on
September it burned up in the gas giant's atmosphere, bringing
a spectacular thirteen years of science in Saturn's orbit to

(00:46):
a poignant close. The spacecraft was low on fuel, and
to avoid an accidental crash into what a Saturn's potentially
habitable moons, NASA had long ago decided that the best
way to dispose of the mission was to burn it
up in Saturn's upper atmosphere. The agency wanted to avoid
earthly contamination on these pristine alien environments. Before its fiery death, However,

(01:06):
Cassini took unprecedented measurements of the mysterious ring gap region
to reveal some surprising ring dynamics. The mission scientists expected
to detect some whispy elemental gases in this empty region,
Cassini's particle instrumentation found a smorgas board of elements and
molecules raining from the rings down to the planet's atmosphere.
They estimated around ten tons of material that's about nine

(01:29):
thousand kilos is falling onto Saturn from the rings per second.
That means that Saturn's rings will eventually disappear and will
have existed only for a short blip of Saturn's four
billion year lifespan. So far, researchers have used Cassini's ring
dives to estimate when Saturn acquired its famous rings. When

(01:49):
Cassini zipped through Saturn's ring plane, mission managers allowed the planet,
its rings and moons to gravitationally tug at these speeding spacecraft.
These extremely slight tugs resulted in tiny change is in
the probe's trajectory, which could be precisely measured. Those changes
allowed scientists, too, for the first time, make a very
good measurement of how much mass is holed up in

(02:09):
Saturn's rings. After analyzing the final set of orbits, However,
the extent to which Cassini's trajectory was deflected initially didn't
make sense. It didn't match the predictions by theoretical models.
It turned out the Cassini's motion was being additionally altered
by massive flows of material at Saturn's equator, inside its
thick atmosphere about six thousand miles or nearly ten thousand

(02:30):
kilometers deep. These massive flows are moving about four percent
slower than the visible upper atmospheric clouds, causing a gravitational
anomaly that wasn't predicted. Cassini Project scientist Linda Spilker of
NASA's Jet Propulsion Laboratory set in a statement, the discovery
of deeply rotating layers is a surprising revelation about the
internal structure of the planet. The question is what causes

(02:52):
the more rapidly rotating part of the atmosphere to go
so deep and what does that tell us about Saturn's interior. However,
with this normally partially explained, scientists were free to measure
the gravitational influence of Saturn's rings, and thus measure their mass.
The researchers estimate that the total mass of Saturn's rings
is approximately that of Saturn's moon Mimus. Considering Mimus is

(03:14):
two thousand times smaller than Earth's spoon, there certainly isn't
a lot of material in Saturn's rings. Scientists had previously
relied on density waves or ripples through the rings caused
by the motion of the sixty two moons in Saturn's
orbit to estimate ring mass. Although these estimates were also low,
astronomers have always assumed there was some kind of hidden
mass in large blocks of material that remained unseen. Now,

(03:38):
with the precision measurements made by Cassini's final orbits, we
know that there is no hidden mass. The lower the
mass of the rings, the younger they are, and because
they are predominantly made of ice, if they were older,
the ring material would have become contaminated by interplanetary debris
dulling them. In. Saturn's rings, as we're acutely aware, are
beautifully bright. Previous estimates of ring age have been far

(04:00):
ranging from four point five billion years the leftovers of
when Saturn itself was forming, to a few tens of
billion years, but with this new finding in hand, it
looks like the rings are very young, formed less than
one hundred million years ago and perhaps as recently as
ten million years ago. Where the rings came from remains
more of a mystery. It's possible that an icy object

(04:20):
from the Kuiper Belt or an arrant comet became entwined
in Saturn's gravitational field and succumbed to the planet's powerful tides,
was ripped apart and eventually ground down to create the
banded rings we know and love today. Although Saturn's rings
will be gone in a hundred million years, it doesn't
mean that our Solar systems ringed planet days are gone forever.
If Saturn can create them, there's little reason why Jupiter, Neptune,

(04:43):
or Uranus can't shred anice the object create another bright
ringed planet display in the distant future. Today's episode was
written by Ian O'Neil and produced by Tyler Clang for
iHeart Media and How Stuff Works. For more on this
and lots other bright topics, visit our home planet how
Stuff Works dot com. MHM