NARRATOR: In the beginning,
there was darkness. And then bang, giving birth to
an endless expanding existence of time, space, and matter. Every day, new discoveries
are unlocking the mysterious, the mind blowing, the deadly
secrets of a place we call the universe. If you thought Saturn was
the only ringed planet, think again. All four of the giant
planets orbiting the sun have ring systems. Even Pluto might have rings. NARRATOR: Flying a spacecraft
through them would be deadly. JEFF CUZZI: These
particles orbit Saturn at 15 times the speed
of a rifled bullet. NARRATOR: So to find
them, ring hunters must push technology
to the limit. It was a challenge,
like taking a picture of a cat in a coal bin. NARRATOR: From the
outer reaches of the cosmos to a surprising ring
system in our own backyard, this is "The Hunt
for Ringed Planets." [music playing] This is the sixth
planet from the sun. Don't recognize it? That's because
something's missing. Without its iconic rings, Saturn
would be just another planet. They are the key to its beauty. The exhilaration of
seeing Saturn's rings through the telescope
can't be overstated. It is just such a
marvelous sight. NARRATOR: People have been
in awe of Saturn's rings since Galileo first discovered
them in the year 1610. Since then, astronomers
have applied everything they know about the original
ringed planet in their hunt for more. But when we gaze at
Saturn's rings, what exactly are we looking at? The perfection viewed from
Earth masks a scene of chaos. Things are bumping
into each other and spattering off
of one another. And so it's a very sort of
chaotic, icy, rubble field all moving together around Saturn. NARRATOR: Over
time, ring hunters found, not just one ring, but
a series of seven main bands around Saturn's equator. The first really detailed
views of Saturn's rings came from the Voyager
spacecraft around 1980. And those photographs
were truly breathtaking. NARRATOR: Each ring is made
of trillions of particles, ranging in size
from a grain of dust to something as big as a house. They were easy to see, since
they're the brightest rings in the solar system. They glisten because they
are so tightly packed and because the chunks
are highly reflective, being almost 100% ice. If you were positioned
below Saturn's rings but a few yards away, you
would see this vast expanse of boulders and ice
balls, snow balls. And through some parts,
you could see stars on the other side. But other parts
would be so thick, that they would be opaque. It would be a wonderful sight. NARRATOR: Astronomers named
the seven main rings simply by the letters of the
alphabet but in the order they were discovered, A, B,
C, D, E, F, and the last, detected in 1980, G.
All told, ring hunters had found a system that
sprawled a whopping 180,000 miles in diameter. The rings, from edge to edge,
are almost 2/3 or so as wide as the distance from the
Earth to our own moon. So they're quite vast. NARRATOR: Yet,
incredibly, the rings form a single plane
that is wafer thin, averaging less than 30 feet. They're very flat. It's like a sheet of paper
the size of Central Park. NARRATOR: But these
beautiful structures are also turbo charged hellions. Their icy particles
scream around the planet at up to 53,000 miles per
hour, like speeding cars on a never-ending
cosmic race track. At these high
velocities, the rings spell certain death for anything
daring to venture too close. These particles orbit
Saturn at 15 times the speed of a rifled bullet. NARRATOR: A chunk,
just two inches wide, could blast a deadly
hole in a spacecraft. The particles are like race
cars at mind-bending speeds. Yet, like these cars,
each particle in the ring is moving at almost the same
speed as the ones around it. But since their speeds and
directions don't match exactly and are sometimes changed
by forces around them, the icy chunks relentlessly
bump and jostle, just like race cars in the
heat of competition. Most bumps are low impact
and don't have much effect. But at times, a crash can send
a particle hurtling into space. What keeps these rocketing
ice balls in a ring? The powerful force of
Saturn's gravitational pull. If you suddenly took
Saturn's gravity away, then the ring particles would
go flying off in the directions that they were going at the
moment that Saturn disappeared. NARRATOR: Instead, the gravity
of the planet and the velocity of the particles are
in perfect balance, so that the particles are
eternally falling or curving in towards the planet but
never getting any closer. But Saturn is not the
only source of gravity. The particles in the
rings have their own. And it is relentlessly trying
to pull them into a cluster to form something larger,
like a small moon. Every particle is attracted
to every other particle. And the more massive
ones have a bigger pull. And the closer you are,
the more the pull is. NARRATOR: But the
gravity of the particles works against the
gravity of Saturn. It's an eternal war. There's this constant battle,
if you like, between the force of gravity trying to
pull things together, gravity of the ring particles,
and Saturn's gravity trying to tear it apart. NARRATOR: Saturn's gravity
pulls particles away from each other because of a
universal law about the speed of objects in orbit. The closer you are
to Saturn, the more quickly you need to
move to stay in orbit. If you're not
moving really fast, you'll fall into the planet. NARRATOR: Particles
of Saturn's innermost ring tear around at more
than 30,000 miles per hour faster than those in
the outermost ring. Even if one icy chunk is just
a foot closer than another, there will be a tiny
difference in speed. That difference is enough
to prevent the particles from staying together. Even over very
small distances, the inside particles
are moving faster than the outside particles,
stretching them out along these ring arcs. So you'll never get the
rings coalescing back into a solid body. NARRATOR: This perpetual
battle of particles grouping into small
structures, being pulled away, and regrouping has maintained
the rings for millions, possibly billions of years. They're sort of
jostling each other and bumping into each other,
feeling their own very, very weak gravity continuously
forming transient structures, which come and go. The whole ring system is
in a very nice balance. NARRATOR: The balance of gravity
holds the ring system in place. But it's the motion of spinning
around the planet that creates their breathtaking form. We've come here to
a pizzeria to show how the natural form for a very
rapidly rotating object is a thin disk. So we're starting out with
a piece of pizza dough that's not spinning and is
pretty much a round lump. When the dough is
thrown and it's spun up, it naturally flattens
out into quite a very thin, disk-like shape. NARRATOR: The centrifugal
force from the spinning causes the dough to flatten out. For a similar reason,
the rapid orbital motion of the particles in Saturn's
rings, the spin, if you will, of Saturn's rings allows it
to form into a very stable, very long-lived,
extremely thin disk. NARRATOR: But if the
rings are so stable, why did they disappear two years
after the first ring hunter, Galileo, discovered them? In 1610, he made his
first observation of the rings, which, through
his primitive telescope, appeared as circles on
either side of the planet. When he looked again in
1612, the circles were gone. Galileo was baffled. But the answer to
this mystery is obvious to modern astronomers. Galileo didn't see these
protrusions the second year because, at that time,
Saturn's rings were nearly edge on to his line of sight. And so they were
essentially invisible. NARRATOR: An edge
on view occurs twice in the 30 years it takes
Saturn to orbit the sun. The angle at which
the rings are seen is constantly changing
because the planet itself tilts 27 degrees. So this is Saturn. And it's tilted 27 degree. So it's facing me. I can see the rings from above. Saturn moves. So now it is here. And I could see the
rings in profile as a straight looking line. Then it moves on the other side. And you can see the
ring from down below. NARRATOR: While Galileo's
mystery was swiftly resolved by later ring hunters, one of
the most fundamental questions about Saturn is hotly
debated to this day. Where did the rings come from? It's the biggest
conundrum in ring science, really, the origin
of Saturn's rings. NARRATOR: Two theories
vie for dominance. One holds that the rings formed
just after the birth of Saturn 4 and 1/2 billion years ago. They were the leftovers from
the spinning disk of material that became the planet. The second theory puts their
age just 100 million years, a relative newborn. If the dinosaurs had
telescopes and looked up at Saturn, there might not
have been a ring system there. It's probably much
newer than that. But we happen to be the lucky
ones that the rings are there at the same time that we have
the technology to explore them. NARRATOR: The belief is
Saturn's rings were created by a cataclysmic event. But was it a massive collision
between a moon and an asteroid, or an invisible force that
ripped the moon into billions of pieces? They are some of the most
awe-inspiring structures in the solar system,
wider than 22 Earths, while only 30 feet thick. But the biggest mystery
facing ring hunters is how Saturn's rings got there. Many believe that the rings were
born when one of Saturn's moons was ripped to millions
or billions of pieces by a powerful force
called tidal effect. Tidal effect is any
gravitational interaction where one side is getting tugged
on more than the other side. So if I had a big massive
object right here closer to this shoulder, it would
pull more on the shoulder than this one, which
is further away. And it could pull me apart. NARRATOR: In a black hole, where
gravity is violently strong, tidal effect could pull apart
something as small as a human. If you've heard the
phrase spaghettification, a black hole is pulling on
your feet more than your head. And it's stretching you out
into a long strand of spaghetti. NARRATOR: In less extreme
places, like our solar system, the impact of tidal
effect is only felt by large bodies
like planets and moons. Anyone who has gone
to the seashore has witnessed the moon's
tidal effect on the Earth. The part of the Earth that's
nearest to the moon gets pulled more strongly
toward the moon than the far side of the Earth. So the Earth takes on
this bulgy appearance. So you can see, at the shore,
that the water goes up and down over a roughly 12 hour period. NARRATOR: But the
moon's tidal effect doesn't only pull the oceans. It pulls the entire planet. Something that's
not often recognized is that the rock ball of
the planet itself changes shape as well. In fact, Earth's diameter in
the direction toward the moon is a foot or two longer than the
diameter in the perpendicular direction because the whole
Earth is stretched toward and away from the moon. NARRATOR: Planets also have a
tidal effect on their moons. In fact, since planets
are larger than moons, they have more gravity and
create stronger tidal effects. Our moon is made of
rock and metals, far too solid to be ripped apart
by Earth's tidal effect. But some of Saturn's moons
were loose conglomerations of ice, dust, and rock,
sometimes called rubble piles. JEFF CUZZI: A rubble pile
might be like a snow cone or something like this. It's put together
with no strength, except just little
surface forces, a very low strength object. NARRATOR: Some
scientists believe one of these moons strayed
too close to Saturn 100 million years ago. ALEX FILIPPENKO: The
loosely held moon would get ripped apart into
thousands or millions of pieces of a wide range of sizes. And they would have different
distances from the planet and, thus, would take
on different orbits. The different periods
of the different orbits would gradually spread the
stuff out into a ring system. NARRATOR: Only
further exploration can determine whether
the rings of Saturn were created by tidal effect,
the destruction of a moon by an asteroid, or
from leftover debris when the planet first formed. But astronomers recently
discovered particles joining the ring right
before their eyes. They found that Saturn's
outermost band, the E ring, only exists because of violent
upheavals on one of Saturn's moons called Enceladus. What erupts from this
extraordinary moon is water. And that water
squirts out in geysers and instantly freezes,
kind of like the water in snowmaking machines
at ski resorts. NARRATOR: These plumes
of frozen particles shoot hundreds of miles off the
surface of the moon, where they enter into orbit around
Saturn and form the E ring. Besides the unexpected thrill
of seeing material added to one of Saturn's rings, astronomers
discovered another surprise locked within the microscopic
particles of the E ring. In June 2009, scientists
found trace elements of chemicals commonly known
as salt and baking soda. The thing that's so exciting
about finding both the salt and the carbonates
in the E ring is that those are the
kinds of things that suggest a liquid
ocean inside of Enceladus. And just like on Earth, where
life formed in the oceans, we believe, it could very well
be true that life has formed inside of Enceladus. This is a really
exciting possibility, but it's, by no means, solved
because we don't see the sodium in the plume coming out. These observations suggest
some other explanations. We don't know. We have to keep exploring. NARRATOR: Astronomers
are, in fact, getting streams of new data on
Saturn and its rings every day from a spacecraft launched
in 1997 called Cassini. JEFF CUZZI: Cassini is about
as big as a small school bus. It's the biggest interplanetary
spacecraft NASA has ever built. NARRATOR: After a
seven-year journey, Cassini became the
first spacecraft to enter into an
orbit around Saturn, giving mankind a front row
seat to the sixth planet from the sun and its rings. Already, it's gone over
100 times around Saturn. By the end of the mission,
it will probably have gone around Saturn 200 times. NARRATOR: Cassini has captured
images closer than ever before, revealing a wild
world of shifting forms and surprising variation. From a distance, it
almost looks like the rings are a solid body, just
a sort of stately march around the planet. But it's not that way at all. It's a very chaotic,
messy process. The study of
rings used to feel like we were studying geology. And now it feels more like
we're studying the weather. NARRATOR: To the
astonishment of astronomers, Cassini revealed
particles in one ring, forming a towering wave. First seen in 2009, the wave
rose at the edge of a ring to the terrifying height
of more than a mile. The rings themselves are
very thin, only about 30 feet. So it's as though you were on a
shallow lake only 30 feet deep. And then a mile-high
wave comes right at you. It's really remarkable. NARRATOR: The cause
of this planetary surf turned out to be the
gravitational effects from a moon just five
miles wide named Daphnis. Because it's so close to
one of Saturn's rings, the gravitational
pull of this tiny moon is strong enough to
create the gigantic waves. It shows how kind of
powerful and remarkable these gravitational interactions
are between the moons and the rings. NARRATOR: These waves are
only one way that moons put their mark on rings. They also add to the
shapes of the rings, so that you get gaps and
edges and very clear divisions between the rings. NARRATOR: Moons that create
these edges and divisions are called shepherd moons. In Saturn's F ring,
there is a moon on each side that actually herds
the particles into the ring. These moons,
Prometheus and Pandora, are, in essence,
Saturn's cowboys. They work just like cowhands
you'd find on a ranch. - All right, let's go.
- All right. Let's go get them. Get. What we're doing here is much
like what Saturn's moons do to Saturn's rings. We're herding them just like
the moons shepherd the rings. For example, Prometheus and
Pandora heard the F ring. I'm like Prometheus. I'm on the inside. And my partner is
on the outside. That's Pandora. And we're keeping
this cattle in line just like the moons
keep the rings in line. When a moon interacts
with a ring particle, it can kick it into a higher
orbit further from Saturn or kick it into a lower
orbit closer to the planet. NARRATOR: Pandora, being
further from Saturn, orbits more slowly than the
particles in the ring. If a particle strays out,
Pandora's gravity pulls on it. This slows the particle
down, causing it to fall back to the ring. On the inside, Prometheus orbits
at a higher speed than the ring particles. Its gravity pulls them forward,
increasing their energy and causing them to
move away from Saturn. The overall effect is that the
two moons confine the particles between them, creating
a sharply defined ring. The moons play an enormous
role, a very fundamental role in the way the rings look
and how they got formed. The moons can shepherd the
particles in the rings, so that you get gaps and
edges and very clear divisions between the rings. So the rings are completely
dominated by the moons from the beginning to the end. NARRATOR: The glittering
bands of Saturn sparked a quest for more rings. Yet, they were the only
known rings for centuries. Ring hunters dreamed
of finding others, suspected there
were more, and, yet, could see nothing
visible like Saturn's. As the 20th century waned,
a small team of astronomers focused a telescope on
Uranus in hopes of learning about its atmosphere. They weren't ring
hunters at all. And yet, their mission led
to a shocking revelation, triggering the biggest
discovery in rings in more than 300 years. Ever since Galileo
discovered Saturn's brilliant rings centuries ago, the
quest for more rings was on. Yet, hundreds of years rolled
by without another discovery, to the enormous frustration
of ring hunters. So in 1977, when a small
team of researchers staked out the planet
Uranus, their sole interest was its atmosphere. On March 10th, the team
flew a modified jet to the edge of
Earth's atmosphere and trained their telescope
on the seventh planet from the sun. They were waiting for the moment
when a distant star would pass behind Uranus. They were measuring
the brightness of a star as a function
of time as it was going to pass behind the planet. And in this way, you can study
the structure of the atmosphere of the planet. NARRATOR: But as the
star approached Uranus, something strange happened. Before it went behind
Uranus, the light actually blinked out several times. NARRATOR: Stunned
scientists waited to see what would happen
when the star reappeared on the other side. And then after emerging
from behind Uranus, it blinked out
several times as well. NARRATOR: The team had
discovered something completely unexpected. The dips on one
side of the planet were perfectly symmetrical
to those on the other. It meant they had found a
second planet with rings. That was a
surprise and was very exciting to see the first time. NARRATOR: It was the first
new ring system discovered in more than 350 years. And it would open
the floodgates. Two more ring systems
would soon be discovered, one on distant Neptune and one
on the largest planet, Jupiter. So we now know that four
planets in our solar system have rings. And in fact, all four of the
giant planets orbiting the sun have ring systems. NARRATOR: But if rings are
common, why did it take astronomers so long
to find the others? Because the rings of the other
planets are quite different than Saturn's. JACK LISSAUER: It wasn't by
accident that Saturn's rings were discovered back at the
beginning of the 17th century, and no other ring system
was found until near the end of the 20th century. Saturn's rings are broad. They're bright. They're spectacular. The other systems
are much more subtle. NARRATOR: Subtle, in part,
because of their size. A very surprising aspect of
the discovery of Uranus' rings was that they're very narrow. NARRATOR: Most of Saturn's rings
are thousands of miles wide. By comparison, the
majority of Uranus' rings cover less than two miles. The other part is that
they're very, very dark. Whereas the rings of
Saturn are made of ice, and they're very bright, think
about something much darker than tar. They're as black as anything
you can probably see. NARRATOR: What's more, the
outermost rings of Uranus are so dim, ring hunters
didn't find them until 2003. This is largely because there
is almost nothing in them. Throughout the system, there's
clouds of very faint dust at this level of a filling
factor of 1 in 100,000 or 1 in 1 million. NARRATOR: These particles
are spaced so far away from each other, it would be
like a cosmic race track that stretched from the Earth
to the moon and back. And it would have just
a handful of cars on it. It's a radical difference from
Saturn's rings, where particles are often packed in side by
side, bumper to virtual bumper. The outer rings of Uranus
are extremely sparse, but they are not the faintest. That award goes to the outermost
bands around the fifth planet from the sun. Mighty Jupiter has the
most delicate rings of all. So far, astronomers have
identified four ethereal rings circling the planet, an inner
ring, the main ring, and two outer rings. Unlike the icy chunks bigger
than a car found in Saturn's rings, the particles
in the rings of Jupiter are mainly the size
of the finest dust. We often refer to
these as dust rings. But the better word
would be smoke rings. The particles are
microns in size. Smoke coming off of a fire
is basically microns in size. NARRATOR: The rings,
like the planet, are mammoth, sprawling nearly
300,000 miles in diameter. Yet, incredibly, if you
squashed all the particles into a single ball, it would be
no wider than a football field and perhaps as small as the
distance of a first down. There is so little in
the two outermost bands that they are the faintest
rings ever detected in our solar system. Almost invisible, they are
called the gossamer rings. You could actually sit inside
the gossamer ring of Jupiter and not even know it was there. I mean, maybe you'd
hear an occasional ping on your spacesuit as a
dust particle came by. But you would not see anything. NARRATOR: As impossibly faint
as the bands of Jupiter are, it was the search for
rings around Neptune that proved the most
challenging for ring hunters. ALEX FILIPPENKO:
Neptune was suspected to have rings in the 1980s when
the material in these regions blocked the light of a
star that was about to go behind the ball of the planet. NARRATOR: Using the same
technique that had detected the rings of Uranus,
astronomers tried some 50 times to find the rings of Neptune. The results were
maddeningly inconclusive. Exasperated scientists
proposed a radical explanation. Since star light was
occasionally blocked, perhaps there were strange
rings around Neptune that only partially
encircled the planet. We didn't think that
they were complete rings because the blocking of light
on either side of the planet was not symmetrical the way it
was for the rings of Uranus. NARRATOR: Could
it be that Neptune had some bizarre and
mutant ring system? Ring hunters had never
been so determined to solve the mystery. And they had no way to
anticipate how bizarre that solution would be. For more than 350 years,
the only known rings were the bright and
dazzling bands of Saturn. Then, in a space of just
two years starting in 1977, two new sets of rings were
discovered, one on Uranus, the other on Jupiter. But the search for rings
around distant Neptune dragged on for many
more frustrating years. JACK LISSAUER: Neptune
is very, very far away. It's a great distance
from the sun. And therefore, there's not
much illumination on the ring. In addition to that, no
spacecraft went by Neptune until 1989 when Voyager 2 from
NASA went by the last planet in our solar system. NARRATOR: Voyager 2 was the
astronomers' best weapon in the hunt for rings. On August 25, 1989,
the spacecraft got as close to Neptune as
any manmade craft ever would. It captured the best images
ring hunters had seen of the eighth
planet from the sun, an incredible
technological feat. It was a challenge. It was like taking a picture
of a cat in a coal bin under moonlight or something. So would they
reveal that Neptune had no rings, full rings, or
the mysterious partial rings that some astronomers
had proposed? NARRATOR: For more than a decade
before the Voyager mission, scientists had tried
to detect rings using the light of various
stars passing behind Neptune. Some attempts saw
dips in starlight. But they were never
at the same distance on both sides of the planet
like full rings would be. Neptune was exasperating. We knew there was stuff there. But we didn't know what
the configuration was. NARRATOR: So when images
from Voyager rolled in, ring hunters were thrilled. Not only were there
complete rings, but there was something in
the rings that had never been seen before, arcs. The most prominent
feature are a set of arcs, which only
go less than a tenth of the way around the planet. The rest of the
ring, very ethereal. NARRATOR: Arcs were
simply segments of a ring that were
brighter and thicker than the rest of the ring. The incredibly small
amount of material in the rest of the ring
explained why astronomers had not been able to detect
the complete rings from Earth. The arcs lie
within a full ring, but the matter in this full
ring is almost transparent. So we could never see
it before with watching it block starlight. NARRATOR: The discovery
of rings around Neptune meant that all of the gas
giant outer planets had rings. It was a reflection of the
natural order of the cosmos because the disk
shape of rings is one of the most primordial
forms in the universe. The universe contains two
sort of fundamental blueprints for objects. And those are spheres and disks. Spin is a really important
aspect of an object structure. And it will tend to
form into a disk. And so we see disks on
every scale in the universe. NARRATOR: This is why
the rings of Saturn can tell us about the
origins of a much bigger ring system, the one around our sun. GREG LAUGHLIN: Saturn's
rings are a blueprint for the processes that give
rise to planet formation. If we were to go back in time
and visit our own solar system 4 and 1/2 billion years
ago, the young sun would have been at the center. And it would have
been surrounded by a disk of gas and dust. And that disk of gas and dust
would have had planets forming inside of it. And that whole disk would have
looked, to a certain extent, like a system of rings. NARRATOR: The
first planets began to form in the debris disk. As they grew larger,
their gravity cleared out space
in their orbits. Debris that was within their
gravitational influence was added on or
whipped out into space. This is exactly what happened
in our own solar system when Jupiter formed because
Jupiter was massive enough to clear a gap in our own disk. In time, the other planets
in our solar system formed and cleared out
their own orbits, leaving just two spaces for
debris, the asteroid belt and the Kuiper
belt. Together, they create what amounts to a vast
set of rings around the sun. As a blueprint of
our solar system, rings help us understand
our own beginnings. Yet, ring hunters
have long wanted to pursue one of the biggest
prizes of all, ringed planets in other solar systems. GREG LAUGHLIN: We already
know of many planets that have masses similar to
Saturn and compositions similar to Saturn. And it's a good bet that not
all of them, but some of them have spectacular ring systems. NARRATOR: They now
believe they'll discover the first ringed planet
from another solar system very soon with the help of one
of the world's most powerful telescopes, Kepler. Kepler is able to track about
100,000 stars at a time. It was designed to measure the
tiniest changes in starlight, so that it could detect
distant planets that pass in front of a star. GREG LAUGHLIN:
When that happens, the planet blocks out a little
bit of the star's light. And Kepler can detect that dip. If a ringed planet goes
in front of a star, then the rings also block
out the star's light. And that signal can be
measured by Kepler as well. NARRATOR: While Kepler gazes
deep into the universe, astronomers are also
hunting for a new ring within our own solar system. In 2006, a mission called
New Horizons roared off the launchpad. Its 2.7 billion mile journey
will take it to the frozen edge of the solar system. If it survives, it will
become the first spacecraft to fly past Pluto. Astronomers suspect
that the dwarf planet may be the first rocky
object found to have rings. Yet, there is another ringed
planet in our solar system. Its ring is on a
collision course with disaster, which could
lead to chaos on Earth. The four outer planets
of our solar system are all encircled by rings,
some dazzling, some dusty, some remarkably faint. Yet, the quest is
on for one more, the most distant of all,
encircling a frigid rock called Pluto. Once considered to
be a genuine planet, it was reclassified as
a dwarf planet in 2006. In 2015, it may become
the newest member of our solar system
found to have rings. Pluto might have
rings, very faint rings. Or it may some day gain
rings because Pluto is in a region where there are
lots of comets floating around. And if one of them
gets close to Pluto, it might get tidily
shattered by Pluto's gravity, temporarily forming a ring. NARRATOR: A mission called
New Horizons is already a third of the way to a
rendezvous with Pluto. The images it transmits
in 2015 should reveal if the distant dwarf has rings. Yet, ring hunters recently
expected to find a new ring system much closer, on Earth's
nearest neighbor, Mars. There's long been speculation
that Mars might have a ring system. It goes actually
back to the 1970s. And part of the reasoning
now is that everywhere we look in the solar system
that we see small satellites, there is a faint ring
associated with them. NARRATOR: Two small satellites
or moons orbit Mars. Though each is less
than 20 miles wide, astronomers believed enough
dust came off these moons to form a faint ring. They must be producing
clouds of dust. We know that for certain. And the only question is,
when and how does that form into a ring? NARRATOR: Yet, when they trained
the powerful Hubble telescope on Mars in the 21st
century, they saw nothing. We've looked twice now. And we have not seen anything. So we're beginning to get a
little bit puzzled as to why there are no rings of Mars. NARRATOR: The Earth
itself once had a ring. Giant chunks of red
hot rock whizzed around the planet for at least
a few years and then vanished. How could that have been? 4 and 1/2 billion years ago,
when the Earth had just formed, a giant body the size of
Mars smashed into our planet. And that formed a temporary
ring that was even more spectacular than
Saturn's is today, in the sense, that it was
not just a big, thick ring, very massive, but it
was glowing red hot. As the molten rock cooled,
some was thrown back to Earth. And some flew out into space. The rest of the material
condensed into a sphere that became our moon. But Earthlings don't
need to feel left out. Our home planet has a new ring. And this one is
just 50 years old. It's not made of dust or icy
rock but metals and silicon. It's a ring of satellites. The Earth has built itself
a highly technologically complicated ring of satellites
that will last for millions of years. NARRATOR: Comprised of
some 400 satellites, it's the only known ring
created by life in the universe. It hovers 22,000 miles
above the Earth's equator in a geosynchronous orbit,
where their speed will hold them in exactly the same spot
over the planet indefinitely. The geosynchronous satellites
are this very special sort of subcategory of satellites. And they form a true
ring around the Earth. And it's a ring, in the sense,
that they're orbiting particles that are continuously falling
around the Earth, much the same way as Saturn's rings,
gravel-like icy particles that are all falling around Saturn. NARRATOR: Earth's ring
is a critical component to human communications. But it's heading for disaster. What we know in ring studies
is that you put enough things in one place, and they're
going to start colliding. NARRATOR: In fact,
in February of 2009, two satellites in a
low-Earth orbit did collide. The crash sent shockwaves
through governments and the scientific
community around the world. We had two large satellites. And they collided. They blew themselves
to smithereens. And we now have maybe
10,000 objects all in orbit around the Earth. Each of those is a bullet. And each of those is moving
perhaps at 10 miles per second. And any one of those
has the capacity to take out another satellite
should another collision occur. NARRATOR: Each new satellite
in the geosynchronous orbit is like adding a race
car to the track. Every one increases the
danger of a collision. If two collide,
the flying debris could destroy the entire
ring, throwing communications on Earth into chaos. Eventually, it will just be
an unsafe place to put anything because you've got swarms of
bullets flying past you all the time. NARRATOR: Whether
artificial or natural, ring hunters continue to
pursue the prized bands because they're one of
the most essential forms of the universe. Without them spinning into
galaxies, solar systems, and planets, life, as we
know it, would not exist. Rings, it turns out, are the
beginning of what is possible. It is true that we
go billions of miles out to try to see
what's out there, but it's because it
tells us how we formed, what our own backyard is like,
what our solar system is like. We learn more about what's
possible in other worlds. We learn more about what's
possible here on Earth.
