Y Cosmos: Bywyd Estron Y Cosmos

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-Could there be life

-anywhere else in the cosmos?

-It's a big question.

-Is there life beyond earth?

-If so, what sort of life is it?

-Of the 50 billion sun-like stars

-in our galaxy...

-..one in five should have planets

-warm enough for life.

-The odds are better than

-winning the lottery.

-There are many planets which

-could sustain life in the universe.

-Which one has life on it?

-Other planets like the earth

-that are home to life?

-This programme will reveal

-they do exist.

-Astronomers knew of just one star

-with orbiting planets 20 years ago.

-Our star - the sun.

-In the 1990s,

-we thought planets were rare things.

-But no, they're very common.

-If you look at a star in the sky...

-..it's likely

-there's a planet orbiting it.

-Astronomers discovered a new planet

-in 1995 - 51 Pegasi b.

-It was similar to Jupiter,

-but 50 light years from the earth.

-It was the very first exoplanet

-to be found.

-And after finding one,

-scientists wanted to find more.

-I'd say we're in the golden age.

-Go back 20 years

-and we knew of no exoplanets.

-We found the first one in 1995.

-Over 1,000 have now been discovered.

-It's certainly one of the most

-exciting areas in astronomy.

-The vast majority of exoplanets were

-discovered in the last four years...

-..thanks to a telescope

-called Kepler.

-Things started to change

-15 years ago.

-Launching the Kepler space telescope

-transformed everything.

-Kepler looks for shadows

-in front of distant stars.

-A shadow means a planet

-has just crossed in front it.

-When a plant orbits a star, and that

-orbit points straight at us...

-..the planet will move

-in front of the star...

-..and there will be

-a tiny dip in the light.

-Kepler can find planets...

-..but it can't tell

-what kind of planets they are.

-To find out, astronomers turn to the

-most powerful telescopes on earth.

-It's nine o clock at night

-in Berkeley, California.

-Astronomer, Geoff Marcy's day

-is just beginning.

-Tonight, he'll control

-the Keck telescope in Hawaii...

-..to look at the hundreds of new

-exoplanets discovered by Kepler.

-Carolyn is there,

-in the lower panel.

-She's at the Keck headquarters...

-..at 2,000 feet up the flanks

-of the Mauna Kea volcano.

-We give her

-the coordinates of the stars...

-..then she points the Keck telescope

-at each one of the stars.

-That should be the

-centre of the slit there.

-That looks beautiful right there.

-We are ready to begin.

-The first star of the night -

-first exposure.

-Keck measures how planets

-are influenced by their stars.

-Measuring the gravitational pull

-between both...

-..gives Geoff valuable clues.

-What we'd really,

-dearly love to know...

-..is are the planets like the earth,

-with a hard surface...

-..where water puddles and advanced

-technological species can walk...

-..or are the planets a dud gas giant

-not suitable for life as we know it?

-If a planet is rocky...

-..Geoff calculates

-how far it orbits from its sun.

-He's looking for the Goldilocks Zone

-- not too hot and not too cold.

-This planet's location is important

-because it's in the Goldilocks Zone.

-It's far enough from the sun...

-..so that its energy doesn't turn

-the water into steam and vanish...

-..but close enough

-that water remains unfrozen.

-Water in liquid form

-is crucial for life.

-We used to think

-the earth's distance from the Sun...

-..defined the habitable zones.

-A few decades ago,

-scientists were confident...

-..that there could be life

-on planets such as Venus and Mars.

-But Venus is too hot

-and Mars is too cold.

-So it seemed

-that the distance needed...

-..between a planet and its sun to

-sustain any life was very limited.

-Since discovering exoplanets,

-scientists now believe...

-..that the distance

-between a planet and its star...

-..is not the only factor to

-determine if it can sustain life.

-Planets far from their sun

-can be heated by greenhouse gases...

-..such as carbon dioxide.

-Planets orbiting much closer to

-their sun can avoid overheating...

-..if their surface is pale

-and highly reflective.

-The zone that could sustain life is

-much wider than originally thought.

-After a few years of searching,

-the Kepler and Keck telescopes...

-..have made

-some astonishing discoveries.

-Using a tiny patch of sky,

-they calculated...

-..how many habitable planets could

-be in our galaxy - the Milky Way.

-Geoff and his PhD student,

-Eric Petigura have the answer.

-It's big news.

-Good morning.

-Welcome to the Kepler news briefing.

-First, Eric Petigura.

-Today, I'm happy to report

-that 22% of sun-like stars...

-..harbour a planet

-in the habitable zone.

-That is, a planet that's between one

-and two times the size of earth...

-..and is bathed in a similar amount

-of stellar intensity.

-It's a historic announcement.

-There are around 11 billion

-potentially habitable worlds...

-..in the Milky Way.

-I'm old enough to remember

-man walking on the moon.

-I've lived through

-many of these historical events...

-..but I must admit,

-launching Kepler really was special.

-We're finding many more planets.

-We're bound to find life

-on one of these planets.

-And we now know the best place

-to find alien life.

-Kepler-62,

-a star system with five planets.

-They're rocky, like the earth, and

-they're within the Goldilocks Zone.

-What's interesting is that life

-could be sustained there.

-What's special is that it's only

-10% bigger than the earth...

-..and it's right in the middle

-of the Goldilocks Zone.

-Exoplanet 62F lies on the

-outer edge of the Kepler-62 system.

-This far out,

-water would be locked in ice.

-But if 62f has an atmosphere...

-..the greenhouse effect

-may have melted enough water...

-..to create puddles,

-where simple life can thrive.

-Its sister planet 62e

-is very different.

-Sitting closer to its sun...

-..astronomers believe

-there's a potential paradise here.

-Warm waters break on golden sands,

-basking in tropical temperatures.

-On earth, in similar conditions,

-life thrives.

-Kepler-62 is exciting because it's

-so similar to our own solar system.

-But does alien life

-need a sun-like star to survive?

-Does it even need a planet?

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-Astronomers believe there may be

-11 billion exoplanets in our galaxy.

-A quarter of these exoplanets

-orbit sun-like stars.

-But there's more than one

-type of sun in the cosmos.

-Recently, astronomers

-have been looking for planets...

-..orbiting a special kind of star,

-called a red dwarf.

-What we're seeing here...

-..is an image of our sun

-taken a few hours ago.

-Right over here,

-we have an artistic impression...

-..of a red dwarf star.

-From earth,

-red dwarfs are so small and dim...

-..they're invisible

-to the naked eye.

-But if you could see them,

-the sky would look like this.

-Red dwarfs outnumber other stars

-by three to one...

-..and they have a lot of

-earth-sized planets orbiting them.

-There are billions

-of these red dwarfs.

-Tens of billions of them.

-The number of planets out there

-is huge.

-Red dwarfs often sustain

-a number of planets...

-..the same size as the earth.

-And they're easy to find.

-If you looked for the eclipse of a

-planet across the face of a star...

-..you can see that this blocks

-a much larger, fractional area...

-..of the surface of the Red Dwarf,

-causing a much larger signal...

-..making small planets

-easier to detect around small stars.

-The orbits

-of these earth-like planets...

-..come with a crucial difference.

-We think our solar system is huge

-and, of course, it is.

-But if our sun was changed

-to a red dwarf...

-..the planets

-would orbit much quicker.

-A year would take weeks

-rather than months.

-For a planet to be habitable here,

-it has to be closer to its star.

-Red dwarfs radiate far less energy

-than our sun...

-..and the Goldilocks Zone

-is much smaller.

-The surface of a red dwarf planet

-would be red and dull.

-In the sky, the other planets

-would be seen clearly.

-Some would appear eight times

-as large as our own moon...

-..and race across the sky,

-from horizon to horizon...

-..in less than an hour.

-There may be billions of exoplanets

-just like this one in our Milky Way.

-For every earth-like planet

-receiving yellow light from a sun...

-..there are two more,

-bathed in the glow of a red dwarf.

-We knew of only one

-habitable planet 20 years ago.

-That number could now be 33 billion.

-Five planets for every man, woman

-and child on earth.

-And there could be even more.

-We now have the technology...

-..which allows us to find the moons

-orbiting the planets.

-Astronomers are looking beyond

-just planets for signs of life.

-Moons are also being examined.

-Many of them are like Jupiter,

-where life isn't really possible.

-But the moons orbiting

-distant planets, known as exomoons.

-In the future, we may focus our

-efforts on these exomoons.

-And the biggest of these exomoons

-could resemble our earth.

-These exomoons could be just rocks

-or places where water has frozen.

-They could be places where there's

-an atmosphere with water as liquid.

-All sorts of environments...

-..depending on how far exomoons are

-from the star their planet orbits.

-To search for exomoons...

-..astronomers look for double dips

-in the brightness of distant stars.

-When we look at the data from Kepler

-we can we see the planets.

-If there are exomoons orbiting the

-exoplanets, it's the same principle.

-We can see their shadows.

-Despite these moons being

-millions of miles from their sun...

-..they could sustain life,

-because of the moon's geology.

-Some of these moons

-are in very cold places...

-..but because there are other large

-moons pulling on them, they stretch.

-Heat is then produced

-inside these moons.

-Moons tend to orbit

-in elliptical paths...

-..so the distance from their planet

-changes over time.

-When the moon is close, gravity can

-literally raise the landscape.

-This generates frictional heat

-in the core of the moon.

-Heat that could be sufficient

-to sustain life.

-The moon does not rely on a star

-for its heat.

-These small moons

-are so close to larger planets...

-..they are pulled by gravity.

-This friction which comes

-from that generates energy.

-Energy that could possibly be enough

-to sustain life.

-From these exomoons...

-..we could see some of the most

-spectacular sights in the universe.

-Imagine a warm, rocky world

-just like our own...

-..with oceans, mountains

-and weather systems.

-In the sky, a massive

-ringed planet...

-..and a fiery moon

-shooting hot magma into space.

-It's just like a scene

-from science fiction.

-There's bound to be

-exomoons out there...

-..orbiting ringed planets

-like our Jupiter.

-If you were on one of these moons,

-you'd see a ringed planet...

-..with one, if not two, stars.

-We know of exoplanets

-which orbit more than one star.

-In sci-fi, you see planets

-with two stars - two suns.

-That could be a reality.

-So the fantasy could come true.

-We see in fiction and in films

-like Avatar amazing worlds on moons.

-A few decades ago our imaginations

-were focused on planets...

-..but now things have moved on.

-We now know

-that our world is not unique.

-There are tens of billions of

-planets orbiting stars like our sun.

-Planets that could sustain life.

-If life is out there, how do we

-find it, when it's so far away?

-These planets are so far away.

-The problem is we can't go there

-to discover if life exists.

-Even the closest habitable planet

-is too far.

-Voyager 1, our fastest

-space probe...

-..would take over 200,000 years

-to reach it.

-To find alien life in our galaxy...

-..we need something that moves

-at the speed of light.

-So that's what astronomers

-are using - starlight.

-Astronomers realized

-we could split the light of stars...

-..into its rainbow

-constituent colours...

-..and study the properties

-of material in those stars.

-This is the rainbow of light,

-coming from our own sun.

-The black marks, called absorption

-lines, create a unique signature.

-They tell scientists what chemicals

-are in the sun's atmosphere.

-Like human fingerprints that are

-specific to each person...

-..the chemical fingerprints -

-those dark absorption lines...

-..tell us an amazing amount

-about the make-up of that object.

-If we can discover the chemical

-make-up of a star's atmosphere...

-..we can do the same with planets.

-Some are clear signs of life,

-called biosignatures.

-The most important biosignature

-is oxygen.

-If we find oxygen,

-there's a chance of finding life.

-Oxygen reacts with so much...

-..it would disappear

-if nothing was there to produce it.

-If oxygen is present,

-more complex life could be present.

-But there's a problem.

-Examining light from a distant star

-is relatively easy...

-..but searching for oxygen

-on a distant exoplanet...

-..is far more difficult.

-What we're trying to do

-is to find a light from a match...

-..next to a bright spotlight.

-We must hide the light

-that comes from the star.

-Only then can we see

-reflected light from the planet.

-To overcome this problem,

-scientists and engineers...

-..came up with an audacious plan -

-the Starshade.

-This vast space umbrella would open

-in front of a robotic telescope...

-..and block the glare

-of distant stars.

-If it works, we'll be able to peer

-at earth-sized exoplanets...

-..for the first time.

-If we can see the light from a small

-planet next to a bright star...

-..it would be amazing.

-We could then study

-these distant planets...

-..using the same methods used for

-planets in our own solar system...

-..and learn more about them.

-But more work

-needs to be done on the Starshade.

-After years of delay,

-a new team has taken over.

-It hopes to take the first ever

-picture of an earth-like exoplanet.

-Today, NASA engineers

-are testing the mechanism...

-..that will open the delicate petals

-of the Starshade.

-This truss

-becomes the size of a house.

-Each of the 60 points

-must be located...

-..to within a 20,000th of an inch.

-This is our third time.

-We change it each time.

-Things happen

-that we didn't expect.

-Some of those things will happen

-as we deploy it now!

-The engineers watch

-as the petals open.

-One snagged tape would be enough

-to throw the petals out of position.

-As each strut tightens,

-the team is nearly there.

-Well done, everybody!

-Well done, everybody!

-

-Good job, David.

-If all goes well, Starshade

-will be launched into space...

-..perhaps giving the world its first

-glimpse of a living exoplanet.

-When we get that first image...

-..on the front page of newspapers,

-it'll be like the moon landing.

-The entire world will say, "Wow!"

-We'll finally answer the question -

-is there life on another planet?

-To find that no life has developed

-elsewhere in the universe...

-..would be a shock.

-It would be very sad to discover

-that we are alone.

-When we get the picture of a living

-exoplanet, another question remains.

-What will alien life be like?

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-Our galaxy is full of planets and

-moons that are similar to earth...

-..with rocky shorelines

-and warm oceans.

-One question remains -

-is there life here?

-We've found planets like ours.

-The next question is...

-..if these planets are similar

-to earth, is there life on them?

-What would this alien life be like?

-Clues lie in our early history.

-Four and a half billion years ago,

-the earth is created.

-Over billions of years,

-the earth was literally on fire.

-Giant asteroids

-smashed into its surface.

-Finally, it stops.

-The earth becomes cool enough

-for solid rock to form.

-Then, something miraculous happens.

-We now know that life appears on

-earth almost as soon as it cools.

-All life on earth,

-animal or plant...

-..relies on the same

-basic chemistry.

-Long strands of DNA...

-..made up from chemicals like

-carbon, hydrogen and phosphorus.

-Through telescopes, scientists found

-the basic ingredients for life...

-..in asteroids,

-in clouds of gas and in stars.

-Most of the universe

-is made of similar material.

-We look at other planets

-and see the organic chemicals...

-..which led to biochemistry

-on earth.

-It takes one additional ingredient

-to turn chemistry into biochemistry.

-Life relies on water.

-Water is the most important molecule

-for life.

-Molecular biologists say DNA is

-the most important factor. Rubbish!

-Other molecules can replace DNA

-but water is unique.

-Water melts almost everything.

-It determines

-how other molecules come together.

-Things like proteins and enzymes.

-Water is so powerful, it can

-nurture life in extreme places...

-..like Mono Lake in California.

-This water, three times saltier

-than the sea...

-..is so alkaline

-it can burn through clothing.

-Mono Lake should be dead,

-yet bacteria and life thrive here.

-Astrobiologists

-study extreme habitats like this...

-..to understand where else

-in the galaxy life could exist.

-By looking at those environments,

-we can map out the limits of life.

-How cold, how hot how salty,

-what range of pH.

-By mapping out those limits,

-we have a guide book...

-..for how to search for life

-on other worlds.

-When we talk about

-what's possible...

-..we fall back on Darwin's ideas

-and what has evolved.

-Life evolved to suit its environment

-not the other way around.

-If distant exoplanets have liquid

-water, they could also have life.

-But what sort of life?

-I think, if alien life exists...

-..it would look similar

-to life as we know it.

-We make an educated guess

-by looking at these distant worlds.

-On red dwarf stars, plant life

-may be purple, not green...

-..to extract the maximum amount

-of energy from the dim red light.

-Sci-fi suggests

-weird-looking monsters...

-..but the truth is,

-we could all look the same.

-Evolution on earth favours similar

-shapes in similar environments.

-In water, it's easy to mistake

-a dolphin for a shark...

-..even though one is a mammal

-and the other is a fish.

-On another planet,

-the basic shapes would be similar.

-It's likely that the same physics

-and chemistry in the universe...

-..will lead to

-a similar kind of evolution.

-We may not see birds or fish

-on other planets...

-..but the same rules

-govern evolution.

-Exoplanets are so far away it may be

-hundreds or thousands of years...

-..before we're able to see an alien

-face to face.

-But we may hear from them

-much sooner than that.

-In Northern California,

-42 satellite dishes scan the sky...

-..hoping to hear ET phone home.

-Seth Shostak is

-the senior astronomer for SETI...

-..the Search For Extraterrestrial

-Intelligence.

-He believes alien civilizations may

-be sending radio waves into space...

-..and the Allen Telescope Array

-listens for them, day and night.

-When you think of finding

-intelligent life beyond earth...

-..aliens, as they're known, there

-are many approaches you could take.

-You could try and go there,

-but they're light years away.

-We could wait for them

-to land in the back yard.

-A lot of people

-are convinced that they have.

-We try and pick up

-radio signals or light signals.

-Something that allows us

-to find them at home.

-Radio waves are the best means

-for cosmic communication.

-They're easy to create

-and very powerful.

-Radio waves

-can punch through vast clouds...

-..and carry huge amounts

-of information.

-Best of all,

-they travel at the speed of light.

-The idea is to listen out for Radio

-Cymru coming from another planet!

-If there is

-intelligent life out there...

-..they're bound to have

-telecommunication systems...

-..and radio broadcasts must be

-happening all over the universe.

-This big reflector picks up signals

-that are coming from space...

-..assuming there are any...

-..and it reflects them back

-to this secondary reflector.

-That then bounces them back inside.

-Inside, this is where the rubber

-meets the road - it's the receiver.

-It looks like some sort of death ray

-but that's because it's sensitive...

-..and can amplify a wide range

-of radio frequencies...

-..from low ones, like 1GHz,

-to high ones, near 12GHz.

-Amplified signals go out through

-a fibre optic running underground...

-..to the control room,

-where they're analysed.

-If we find ET, we book a flight to

-Stockholm and we collect a prize.

-To increase his chances

-of finding an alien signal...

-..Seth and chief engineer Chris

-Munson discuss a dish upgrade...

-..to allow them

-to scan deeper into space.

-Tomorrow, we'll install

-this antenna to your left.

-If all goes well,

-we'll have this telescope...

-..standing up and singing

-within eight to nine months.

-We'll be comparable to the best

-radio telescopes in the world.

-Twice the sensitivity.

-ET can be 40% further away

-and we'd still hear him.

-SETI is an extremely clever idea.

-In the days before we were able to

-send probes into space...

-..to look at our nearby planets

-and moons...

-..all we could do was hope somebody

-out there would send us a message...

-..saying, "Yes we're here!

-May we have your attention?"

-So far, SETI hasn't heard a peep.

-Astronomers remain optimistic,

-but time is not on their side.

-In another 50 years, SETI will have

-surveyed the entire night sky...

-..and silence

-would be a major setback.

-If it makes sense

-to try and eavesdrop on ET...

-..this will work before mid-century.

-If it hasn't worked

-by mid-century...

-..they're not out there,

-they're not using radio...

-..or you're doing

-the wrong experiment.

-If this is going to work,

-it's going to work soon.

-There are other ways

-of looking for intelligent life.

-If there's life

-on more than one planet...

-..it's possible they use lasers to

-communicate from planet to planet.

-Geoff Marcy thinks it's possible

-to pick up these laser signals...

-..using giant optical telescopes

-like Keck.

-This is a star

-that has two planets...

-..this second orbiting the star

-lined up with us at the earth.

-If there's any radio communication

-or laser communication...

-..between the colony on one planet

-and the other planet...

-..we hope to pick up the

-communication between the planets...

-..as spillover

-that we eavesdrop on.

-No laser signals tonight but

-who knows what tomorrow will bring.

-If ET does call, what next?

-Do we reply?

-And what do we say?

-In what language?

-Do we tell them about our

-traditions, cultures and science?

-You'd send them

-a lot of information.

-If they're 100 light years away...

-..it takes 100 years

-for the signal to get there...

-..and another 100 years

-for the response to come back.

-You'd send it all at once.

-I'd send the Google Servers.

-I would send the internet.

-Let them figure it out.

-Right now, ET's not talking,

-at least not on our frequency.

-We could be listening

-for the wrong things.

-Or should we face the possibility

-there's nobody out there?

-Are we alone?

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-The question remains unanswered.

-Are we alone in the cosmos?

-There's no shortage of planets.

-They're being found

-on a weekly basis.

-In ten years...

-..we've gone from knowing about one

-planet beyond our solar system...

-..to thousands.

-So there's the first tick.

-The next question,

-is there life on these planet?

-Despite every effort,

-there's no sign of life.

-After a 50-year search

-using the latest technology...

-..not a single signal

-has been heard.

-We've searched for

-extraterrestrial life for decades.

-We've listened,

-using radio and radar.

-We've taken satellites

-to look at our closest planets.

-We're yet to find anything

-on another planet.

-It is possible we're alone here.

-Something's not right.

-Billions of planets ripe for life,

-and not a single sign of life.

-The universe is vast.

-There should be life somewhere.

-Why haven't they come to see us?

-Maybe people on other planets

-aren't of the same mindset as us.

-They may like to stay

-in the same place.

-We have developed science.

-On another planet,

-they may concentrate on the arts.

-They might spend all their time

-painting and not looking at stars.

-Imagine if the sky

-was covered in clouds.

-You may not see the stars.

-If you don't know the stars exist...

-..you may think it would be

-too boring to go beyond the clouds.

-This conflict

-is called the Fermi Paradox.

-Some say the jump from simple life

-to intelligent life is rare.

-Our existence is a fluke

-rather than the norm.

-Are we the only intelligent beings

-in the cosmos?

-We may be a quirk, but this is

-where we go back to statistics.

-It's far more likely

-that we're not a quirk.

-People thought that because

-we hadn't discovered other planets.

-They thought we were a chance

-in a million or a billion.

-We are here because of a series

-of cosmic coincidences.

-Events unlikely to be repeated again

-in precisely the same sequence.

-Water, for example.

-If the earth had received a fraction

-more during its creation...

-..we wouldn't be here.

-The quantity of water may have led

-to the evolution of life on earth.

-Too much water

-and we wouldn't be here.

-Too little,

-and life couldn't be sustained.

-We've been very lucky

-to have just the right amount.

-Considering

-that delicate balance of water...

-..and the right amount of energy

-from the sun...

-..we're looking at

-a very small number of planets...

-..with the right conditions

-to sustain life.

-The right amount of water...

-..doesn't guarantee

-the rise of intelligent life.

-In four billion years of life

-on earth, it's only happened once.

-Had someone looked for life here

-a million years ago...

-..they wouldn't have found

-intelligent life.

-For 200 million years,

-dinosaurs ruled the earth.

-Speed, strength and sharp teeth

-were paramount...

-..rather than technology, science

-and intelligence.

-If a giant asteroid hadn't hit

-the earth 65 million years ago...

-..dinosaurs might still

-rule the earth.

-There could be another answer.

-It's possible alien life

-existed and ended...

-..long before we had the technology

-to find it.

-And also what is intelligence?

-We must look at a planet at the

-right time to find intelligent life.

-If we look too early,

-it might not have developed.

-If we look too late,

-it could have died out.

-Despite all the doubts...

-..scientists continue their search

-for other civilizations.

-The potential is there.

-Our home is just one of billions

-of pale blue dots...

-..with the potential for life.

-It's likely we will find life...

-..somewhere in far reaches

-of the universe.

-It will transform our relationship

-with the universe.

-Scientists keep discovering new

-places where life might flourish.

-On worlds just like ours

-and even on moons.

-I'm hopeful, but I don't think

-we'll find it in my lifetime.

-But 20 years ago I didn't think we'd

-find planets orbiting other stars.

-All this raises questions

-about our life here, on earth...

-..and about the possibility

-of another life beyond the stars.

-It's amazing how much we've learnt

-in the past 20 years.

-In another 20 years, we may talk

-about life on some of these planets.

-In the next century,

-we'll find the answer.

-Is there life beyond the earth?

-I assume there is life

-beyond the earth.

-My frustration is

-that I haven't seen it yet.

-S4C subtitles by Eirlys A Jones

-.