Cosmos: Possible Worlds - First Season

Systems this is prop.

I read you 500, do you read me?

These people are watching their life's work come to an end.

The team is on its way to point.

On another world.

All right. Roger that.

They were all young when they sent her on her way.

These men and women have been traveling vicariously with her for more than two decades.

And now, her work is done, so she must die.

But before she takes the fatal plunge,

they've given her one final, epic challenge.

Gravity has a big bag of tricks,

none lovelier than the ring systems of worlds.

Our own solar system, alone, has four ringed planets.

This one, with the romantic name J-1407B,

is the first we've found circling another sun.

Why haven't we found more ringed planets in our galaxy?

Is it that the rings are so unusual,

or are the methods we use to find exoplanets not very

good at seeing the ring systems that may surround them?

J-1407B's ring system is so vast,

that it eclipsed its star for days.

These rings extend across an astonishing 112 million miles.

They would more than fill the distance between Earth and the sun.

But as enormous as they are, they're shockingly thin.

If the ring system of J-1407B were the size of a dinner plate,

it would have to be 100 times thinner,

as thin as a human hair.

This surprising contrast between the immense territory

of a ring system, and its thinness,

is just as striking in our own solar system.

The outermost ring of Neptune is so dainty,

that it was first thought to be the fragments of a ring.

Not a ring, but a collection of arcs.

That was, until NASA's Voyager 2 spacecraft revealed

that the so-called arcs were clumps,

the thicker parts of a fainter, complete ring.

It's funny that the weirdest planet in the solar system has

attracted the least attention.

Voyager 2 is the only spacecraft that has ever been

sent on a reconnaissance mission to Uranus,

one of the two ice giant planets that circle the sun.

During its 20-year-long summers,

the sun never sets on Uranus.

The winters are equally as long,

20 years of unbroken night.

Unlike its fellow gas planets, Uranus is cold-hearted.

It doesn't generate any internal heat.

Uranus is one crazy world.

The outer edge of Uranus's atmosphere is so hot,

it's hotter than 500 degrees Fahrenheit.

But Uranus also has the coldest clouds in the solar system,

I'm talking nearly 400 degrees below zero.

What kind of ocean is this?

Is it made of ammonia?

Water?

Some scientists think it may be an ocean of liquid diamonds.

might be worth another visit.

Then there's that thing about it being sideways.

Uranus revolves around the sun at a roughly 90 degree angle to its own orbital plane.

What could have happened to Uranus that it got knocked on its ass?

Our best guess is that it went something like this.

Uranus was in a terrible accident.

After the second blow, the rotational axis of Uranus tipped 98 degrees.

There's another world in our solar system that we don't

think of as having a ring.

The rings of Jupiter were so dim that no ground-based

telescope ever saw them.

They were discovered when Voyager 1 came flying by.

Our Saturn is graced by the loveliest, largest,

and brightest ring system of any around our sun.

It's the most distant planet that can be seen with the naked eye,

and it made quite an impression on our ancestors.

When I think of the Babylonians of 3,500 years ago looking up

at the planets and stars,

I wonder how unlikely it would have seemed that one of their

species would actually send an emissary to that

distant point of light.

We are in the Deep Space Network room at NASA's Jet Propulsion Laboratory.

In this place, the most ambitious voyages of discovery are directed and monitored.

Why are these people so emotional?

They have committed their professional lives to

a collaboration with this robot.

And now that partnership of decades is about to end

in a most violent way.

The pathway from our Earthbound helplessness to

our presence in Saturn's skies is about to unfold.

What is that shimmering, unsteady thing we're looking at?

That's what Galileo Galilei asked himself in 1610 when he

became the first human to see Saturn as more than

just a point of light.

So, this is the telescope that made the modern

scientific revolution possible.

You know, you really started something.

You looked through that thing and found the cosmos.

That's not to say you didn't make your share of mistakes.

You guessed wrong at what you thought you saw,

believing that Saturn sported two symmetrical moons

on either side of it.

Two years later, when you took a second look,

you were shocked to find that your "moons" had vanished.

This was because both worlds, Earth and Saturn,

were in motion, and the two worlds had changed in position to each other.

You were now looking at Saturn's rings, edge-on.

The Saturn ring system is 175,000 miles across,

but on average only a few hundred feet thick.

They were too thin for your fledgling telescope to see.

But two years after that, you took a third look.

Now, you thought that the planet had arms.

40 years passed, until a Dutch astronomer named

Christiaan Huygens took another look at Saturn with

his own greatly improved telescope.

Huygens was the first to know that worlds could

be circled by rings, and Saturn was one of them.

He also discovered Saturn's largest moon,

which would later be known as Titan.

When it finally came time for us to visit that world,

our spacecraft bore Huygens's name.

In science, there are the Galileos, the Newtons,

the Darwins, the Einsteins.

And then there's another kind of great scientist.

Not the kind that paints a whole new picture of nature,

but, like Christiaan Huygens,

someone who has much to contribute,

filling in a blank or two on that vast canvas.

Such a scientist was Giovanni Domenico Cassini.

He was born early in the 17th century in the town of Perinaldo,

in what is now Italy.

Cassini didn't start out as a scientist.

He began his career as a pseudo-scientist, an astrologer.

Astrology is a collection of ideas based on the notion that

worlds have certain human personality traits,

and that the influence of these distant worlds,

depending on which are rising and falling at the time

of your birth, will determine who you are and

what your fate will be.

It's another form of prejudice,

making unfounded assumptions about who a person

is without bothering to get to know them.

Astronomy and astrology used to be the same thing,

until there was a great awakening to our

actual circumstances in the cosmos.

In 1543, Nicolaus Copernicus,

a Polish cleric demonstrated that,

contrary to popular belief,

we were not the center of the universe...

the Earth and the other planets travelled around the sun.

Demoting the Earth from the center of the universe

was a severe blow to human self-esteem.

More than a century later,

some people still hadn't gotten over it,

and Giovanni Cassini was one of them.

Cassini accepted a terrific job offer,

an appointment by Louis the XIV,

the legendary sun King of France,

Louis believed himself to be an absolute ruler whose dominion was God's will.

But he was also the first monarch in Europe to recognize

the great power of science.

He knew it was vital to national security.

Louis the XIV was inventing the first modern,

governmental, scientific research institute,

The Paris Observatory.

Cassini told the absolute ruler that he would not be

staying long in Paris, a year or two, at most.

But when the King placed his new observatory at Cassini's disposal,

he lost all interest in returning home to Italy ever again.

For the next 125 years,

the Paris Observatory would be led by a Cassini.

Cassini rewarded his patron with a map of the Moon

that remained cutting-edge for a century.

King Louis financed a research expedition to South America

to obtain more accurate measurements of longitude,

intel of enormous value to the captains of his far-flung

fleet and to astronomers.

Cassini took all these data and became the first person

to calculate the scale of the Copernican solar system

that he had once rejected.

With his increasingly powerful telescopes,

he discovered the length of a day on Jupiter

and the bands and spots on that planet's surface.

Cassini discovered Jupiter's Great Red Spot independently

of Robert Hooke in England, and to this day,

they share the credit.

Cassini went on to determine the length of the day on Mars.

He was only off by three minutes.

When he returned to his observations of Jupiter,

he was stumped by the contradictions in them.

The eclipses by Jupiter's moons did not begin when they were supposed to,

they varied from observation to observation.

Could it be that it was due to changes in the distance

of the Earth from Jupiter, as the two worlds moved through the solar system?

If that were true, then light could not travel at

an infinite speed because it was taking longer to reach Earth.

Was the speed of light finite?

This idea was just too crazy for Cassini, too revolutionary.

He rejected it out of hand.

If he had followed the evidence wherever it led,

he would have given us the yardstick for the cosmos that

we still use 350 years later.

But Cassini, ever the conservative,