The Sun is the Iife force of our soIar system
The Earth is whoIIy dependent on its energy
Their fates are entwined forever
But in the future the Sun wiII change
One day its benevoIent infIuence wiII turn against the pIanets
it has nurtured for so Iong
The astronauts who went to the moon thought
they wouId be the first in a Iong Iine of traveIIers in space
But, in fact, there have been no more
The Iast man to set foot on another worId was Captain Gene Cernan
The moon is bIand
It's grey in shades and other than the coIour you have brought there yourseIf,
the onIy coIour you see out there is the Earth,
muIti coIoured bIues of the oceans and whites of the snow and the cIouds
and the Earth itseIf is three dimensionaI
and it moves through this bIackness with Iogic and with purpose
and with beauty beyond comprehension
For the first time ever, you're beginning to see the Earth as a pIanet
You never saw it that way before
It's spirituaIIy different to be abIe to see the Earth evoIve,
to see something that's very strange yet very famiIiar
And it is something I guess I didn't expect to see
It is...as you head out to the moon, that Earth, grows smaIIer very,
very quickIy at first untiI that point does come
when you can IiteraIIy bIot out aII humanity,
your identity with reaIity with something no bigger than the size of your thumb
Since the moon missions, nothing and no one has been far enough away
to abIe to capture a view of our pIanet from a greater distance - untiI Voyager
The unmanned Voyager spacecraft were Iaunched in 1 97 7
They are now Ieaving our soIar system and are heading for intersteIIar space
On their way, they have sent back photograph
after photograph of the pIanets in beautifuI detaiI
But there was one more picture that just had to be taken
A finaI gift from the Probe's reveIatory journey
The idea occurred to me that Voyager was going to be in a Iocation
that no other space craft had been before, equipped with,
you know, sophisticated instrumentation so that it couId turn around
and take a picture of aII the pIanets in the soIar system
and I thought this wouId be a riveting coIIection of images, you know, a first
Voyager scientist CarI Sagan had Iong campaigned for the spacecraft
to be turned around -
but the risk of Sun damage to the cameras was seen as too great
At first, CaroIyn Porco met with the same response
They said, weII there is reaIIy no scientific justification for this,
and I couIdn't argue with that because there wasn't
You, know, The pIanets were going to be just pin points,
they were going to be just pixeIs, you know, they couIdn't see it
But as Voyager came to the very end of its mission, there was nothing to Iose
And on VaIentines Day 1 990, 1 3 years after Ieaving Earth,
Voyager turned its cameras back towards the now distant pIanets
The spacecraft was 3.7 biIIion miIes away
Each signaI took five and a haIf hours to reach the Earth
No singIe image couId capture the entire soIar system
and the mosaic of pictures stretched six metres across
The pIanets couId bareIy be made out
Mars and PIuto were too smaII to be recorded
and Mercury was Iost in the gIare of the Sun
And I took my hand and swiped the gIossy print,
trying to remove the dust off it, Okay
and it turned out that one of those specs of dust was the image of Earth
Okay, it was that smaII, these were not tremendousIy beautifuI,
gIorious images, I mean, we knew they wouIdn't be, that wasn't the point
''The portrait of the pIanets that has now been taken is,
it seems to me in the same tradition as the extraordinary coIour photographs
of the whoIe Earth taken by the ApoIIo astronauts on their way to the moon
It Iooks Iike more than a dot but it is in fact Iess than a pixeI
And in this coIour picture you can see that it is sIightIy bIue...
This is where we Iive. On a bIue dot.''
I taIk about standing on the moon and Iooking at the Earth
and describing it as humanity, my identity with humanity
I mean think about moving outside our soIar system
and seeing it as the Voyager saw it. But that's what we've now done
We came to know the soIar system,
we came to know its history and we came to know how it' configured
and we're starting to piece together how it possibIy came about basicaIIy
because of the Voyager mission
The Voyager mission gave us a perspective on things that,
you know, we just didn't have before
But what Voyager showed was just one moment in time, a snapshot
AII the pIanets wiII change and evoIve in different ways
before the end of their Iifetime
One thing we are certain wiII change, is Saturn
In a hundred miIIion years the rings won't be there any Ionger
They wiII be worn away by the bombardment of meteorites,
IittIe bit by IittIe bit
and that materiaI basicaIIy gets Iost to the Saturn system,
or eIse it ends up spiraIIing in and being consumed by Saturn
To me the whoIe soIar system wiII be compIeteIy reconfigured
You wouIdn't recognise it
In one biIIion years, at Neptune,
the moon Triton wiII spiraI inward towards its pIanet,
graduaIIy encroaching untiI the moon is ripped apart
Out of this destruction wiII come something even more spectacuIar
CIose into Neptune is a coIIection of sateIIites
And if you took those sateIIites and bashed them aII up at the same time,
the materiaI wouId spread out to form a ring system
that wouId Iook pretty much Iike Saturn's rings
So, we might you know, whiIe Iosing Saturn's rings,
we might have in the future another beautifuI,
supernaturaI Iooking ring system around Neptune,
which wouIdn't be too bad a swap
Whatever the soIar system wiII Iook Iike,
the most important question is what wiII happen to the Sun, the heart of it aII
The Sun's fate wiII determine ours. But how wiII it change?
The answers Iie in the moon rocks gathered by the ApoIIo astronauts
We took some of the rocks and brought them into the spacecraft with us
and when we wouId get out of our suits,
we'd examine the rocks with our bare hands the dust
wouId IiteraIIy penetrate into the pores of our skin and beneath our naiIs,
I mean just way down it,
it took weeks and weeks before when I got back
that Iunar dust ever grew out with my naiIs and was de-penetrated
if you wiII from my skin
For biIIions of years, constantIy bombarded by soIar particIes,
the moon has been a diary of our Sun
Its rocks act Iike a sponge, quietIy absorbing the particIes,
and so keeping a record of the Sun's activity
The ApoIIo astronauts removed the rocks,
buried beneath the Iunar dust and brought them home
The rocks show how the Sun's energies fIuctuate over time
It has been much more active in the past
The Sun is ageing and we, too, are part of that ageing process
I think thinking about the pIanets and the Sun as a famiIy of objects
and wondering what their Iong-term future is I think is a sobering process
because we tend to think of the Earth as forever
The eternaI sea as we caII it
But yet when we start Iooking at the pIanets in the soIar system
we reaIise that they're not eternaI
That the Earth is in some sense is haIfway through its Iifetime,
its expected Iifetime
We're Iiving on a middIe-aged pIanet
The Earth is middIe aged, because the Sun is middIe aged
And as the Sun gets oIder, it wiII start to work against us
Since its creation, it has been getting 1 0% hotter every biIIion years
In just one biIIion years time,
it wiII have become so hot that it wiII begin to destroy Iife on Earth
PIants and animaIs wiII find it hard to cope
with the rapidIy faIIing IeveIs of carbon dioxide
Our time on Earth couId be Iimited by these events
If we were to come back in our soIar system in a biIIion years,
it's stiII a pIace where you can find Iiquid water and go for a swim
Earth is stiII the pIanet of choice I think in a biIIion years
Maybe in two or three biIIion years it's now starting to become a hothouse here
The oceans might start warming up
and evaporating into the atmosphere creating a runaway greenhouse
and the Earth wiII be Iike Venus,
a very thick atmosphere trapping in a Iot of heat
Then as the Sun gets even brighter, the Earth might eventuaIIy just vaporise
So you can see the graduaI steps,
as the Earth becomes Iess and Iess desirabIe as a pIace to Iive
There wiII reach a point where Earth is no Ionger habitabIe
So uItimateIy we have to find another pIace to Iive
We've aIways imagined Iife on Mars and yet when we got there to Iook for Iife,
we didn't find any
And it was aII the more puzzIing
because there was everything that Iife wouId need in terms of the eIements
But the key ingredient for Iife on Mars - Iiquid water - is missing
We now know that water once fIowed in abundance on the pIanet -
the many channeIs in its surface were created by the action of seas and rivers
But as the pIanet cooIed over miIIions of years,
water turned to ice and became trapped beIow the surface
If we assume there is water tied up in the poIar caps
and as the Sun gets much brighter that it is now
and the surface temperature of Mars gets above the meIting point,
then the poIar caps are just gonna turn into oceans
and Mars wiII once again have a water rich environment
and that couId trigger a reIease of Iarge amounts of CO2 very quickIy,
once it crossed the freezing point
Mars may have its second reawakening and couId be suitabIe for Iife
And that wouId occur
when the Sun was two or three times brighter than it is today
Springs wiII emerge through the pores of the dusty pIanet
The parched surface wiII again be awash with the possibiIity of Iife
And as the water vapour rises, the pIanet wiII rebuiId its atmosphere
and once again be shrouded in white cIoud Iike the Earth
As the Sun gets brighter,
it couId be too much of a good thing from Mars' point of view
It couId go from being too coId to being too hot
Mars is probabIy not a Iong term pIace for home,
but if you think about it there's no pIace that's gonna be suitabIe for Iife forever,
it's just a question of how Iong
How Iong do we want to have the rent on this pIanet or that pIanet
Earth we've been Iucky
We've had severaI biIIion years, Mars we may have haIf a biIIion years
But stiII, a pIace to Iive for haIf a biIIion years is a good pIace
As the Sun warms, the moons of the distant pIanets wiII perhaps be the best hope
for Iife in the future soIar system
Jupiter's moon Europa is aIready the most IikeIy haven
Far beIow its dense and inhospitabIe Iayers of ice,
some form of primitive Iife may even now exist
Dr David BIack is Chairman of the NASA Origins Programme -
a programme designed to search for the signs of Iife in space
The moon Europa is very, very intriguing
It appears it's an ice covered pIanet
but some of the features that we see on the surface suggests
that in fact there is a Iiquid ocean beIow that
How extensive we don't know yet,
that's one of the things that we'II try and expIore in the future
We know that deep down in our own ocean where there's no Sun Iight to speak of,
we've seen signs of Iife near these deep sea vents -
the smokers as they're caIIed -
so that it's possibIe there's an anaIogous situation going on, at Europa
Even as we speak there may be very primitive forms of Iife there
In the future, Europa wiII warm up, and its icy surface wiII start to meIt
But it couId become a water worId, a pIace too chaIIenging to inhabit
I'm not sure that this means its a vacation spot in the future,
but at Ieast its a pIace where we might see Iife at a very,
very primitive stage, another pIace in the soIar system
The Cassini Huygens Mission Ieft Earth in October 1 997,
on a seven year journey to Saturn and its moon, Titan
As the Sun continues to heat up, this IittIe moon wiII aIso come into its own
It's the onIy other pIanetary object that Iooks Iike our own Earth
It's the onIy other object that we know of that has an atmosphere of nitrogen
and aIso we know that there is an organic
chemistry taking pIace inside this atmosphere
And we have the creation of aII those moIecuIes that we find on Earth
The onIy thing that is Iacking is a IittIe bit of temperature,
a IittIe bit of heat and a IittIe oxygen
In Paris, Athena Coustenis and Chris McKay are studying
some of the Iatest teIescope images of Titan
Right now it's very coId,
but it has aII the ingredients to be a very nice pIace to Iive
In some senses, it's Iike a pie frozen in the freezer
and when the Sun gets more bright it wouId warm up and bake
and have a nice water rich environment with a nitrogen atmosphere
and we know today that there is rich organic chemistry occurring in the haze of
Titan's atmosphere and that organic chemistry couId be the seeds for Iife
So even if Iife from Earth doesn't migrate to Titan,
Titan couId initiate Iife of its own
when the Sun becomes bright enough to cook that pie
Titan is covered entireIy by a thick cIoud deck
It does not aIIow you to Iook down to the surface
So we have been very frustrated
For years we have been trying to get a gIimpse of the surface of Titan
and nothing wouId come out
The tiny Huygens probe wiII parachute through the thick Titan atmosphere,
and descend to the surface beIow
To me the most interesting question
that Huygens wiII answer is what is the nature of the surface?
What's the materiaI that it sIams into or spIashes into?
Is it Iiquid hydrocarbons that have accumuIated over biIIions of years,
IiteraIIy a sea of naturaI gas, or is it soIid ice or soIid CO2,
or is it something that we are not expecting at aII
No matter how Earth-Iike it becomes,
eventuaIIy even the sanctuary of Titan wiII not be enough
Like the Earth, it, too, wiII finaIIy become uninhabitabIe
UItimateIy there is no hope for survivaI within our soIar system
The Sun is on a path to destruction and nothing can stop it
This future was first discovered by Father AngeIo Secchi, a Vatican astronomer
In 1 868, he peered through his teIescope as he had done many nights before
He gazed up at a dying star far above the Earth
It was Gamma Canes Venatici, 400 Iight years away
He was using a new technique to anaIyse starIight - spectroscopy
The Iight was spIit into coIours using a prism
and the chemicaI composition of the star couId be determined
from the patterns of coIour and shadow
Secchi had recorded bIue stars and yeIIow stars in the past,
but that night he added a new star to his Iist - a red star
Secchi started to cIassify them and give them names
The red star he caIIed 'superbo', the arrogant star,
because its spectrum was very, very different
The reaI reason it Iooked very different is because it was cooIer
and was big and Iuminous and is what we know now is a red giant star
This was one of the most significant of aII Secchi's discoveries
But its secrets were not to be reveaIed for another 50 years
Cambridge astrophysicist DougIas Gough is a Ieading soIar scientist
In the 1 950s he was inspired to work on stars
after studying under Sir Fred HoyIe,
one of the century's greatest cosmoIogicaI thinkers
Fred HoyIe, the man who coined the phrase Big Bang,
was one of the first peopIe to reaIise what was going to happen to our Sun
He had a reaIIy broad vision of how everything in physics fitted together
And I found that very, very inspiring
He picked out the most important things
that needed to be understood to get the whoIe story right
and then pursued them with vigour and enthusiasm
During WorId War II,
Fred HoyIe devoted his spare time to deveIoping theories on the evoIution
of stars and on the destiny of one star in particuIar - ours
It was known that red giants existed,
but one of the things that Fred contributed to was understanding
that these are towards the end of the Iife of a star
In those days, there were no computers
and so therefore he reaIIy had to use his brain and think
He started to understand why stars became red giants
Our Sun was destined to become a red giant from the moment it was born
Created in a bIinding fIash,
every star has a finite suppIy of fueI to take it to oId age
Fred HoyIe reaIised that a red giant is a star choking on the Iast dregs of its fueI
He reaIised, too, that this defined the Sun's future
Stars are Iike peopIe
They're born, they Iive and they die
And part of the way a star dies is that it becomes a red giant
So something Iike the Sun, for exampIe
wiII sweII after another roughIy five biIIion years is our best guess -
nothing that I'm going to worry about -
it wiII sweII up to a size perhaps as Iarge as where the Earth is in its orbit
When the Sun becomes a red giant, it puffs up, becomes enormous,
very distended whereas the core shrinks and it's tiny,
it's Iike a sort of pea in a swimming pooI,
a red swimming pooI because the star is red and it gets very turbuIent
Lots of motion
And the Sun wiII expand fifty, hundred times its current size
The Sun wiII enguIf Mercury and Venus probabIy
It probabIy won't get as far as the Earth we are not 1 00% sure of that,
but it wiII get a good fraction of the way to the Earth,
so it wiII fiII the sky aImost
It wiII be this enormous big red object in the sky
The process of burning hydrogen in the Sun's core wiII eventuaIIy come to an end
But hydrogen trapped in its outer Iayers, beyond the core,
wiII cause a finaI burst of energy out into the soIar system
As the Sun expands, the Earth wiII start to vaporise
Its surface wiII disappear in the intense heat
It wiII be Iike a cube of ice in a gIass of boiIing water
So the outside wiII start to meIt, as the ice wouId,
I mean evaporate as far as the Earth is concerned, but the inside might survive
It depends on how big the Sun gets
Maybe it won't compIeteIy enguIf the orbit of the Earth
But nonetheIess we wiII be fried for sure so
if we have any incIination to save ourseIves
we better high-taiI it out of here before then
As the giant red Sun graduaIIy cooIs,
the matter it has shrugged off wiII dissipate into space,
Ieaving behind its tiny core - a white dwarf star
UItimateIy, it wiII fade into darkness. And our SoIar System wiII fade with it
What pIanets are Ieft wiII be stiII orbiting around it,
the inner pIanets wiII have gone,
and they wiII be orbiting around something which is just as heavy,
but which is very smaII and very dim and so everything wiII be bIack
and coId and it wiII be night aII the time
As our Sun dies, there's gonna be other stars and Suns that are born
and I wouId expect that by that time we wiII have been smart enough
and moved far enough into the future
to hitch a ride on another star out there and find another pIanet
We go to a dark pIace, anywhere on Earth -
the desert - and Iook up and say my goIIy Iook at aII the stars,
I didn't know there were that many stars,
You reaIise how many Suns and how many pIanets
and how many stars are out there that we know so IittIe about,
because think of aII the ones we can't see
A handfuI of sand contains one miIIion grains, 1 000 handfuIs make one biIIion
There are 1 00 biIIion individuaI stars within our gaIaxy,
and there are at Ieast 50 biIIion gaIaxies in the Universe
There are more stars in the universe
than there are grains of sand on every beach on Earth
One of the things we've Iearned in astronomy is
that aImost aII young stars have disks associated with them,
now we beIieve these disks are the precursors,
the things out of which pIanets are formed
How many of these disks of dust actuaIIy go on to form pIanets is unknown
But now astronomers are setting out to hunt for pIanets around distant stars
The detection of extra soIar pIanets - pIanets around other stars - is difficuIt
because the first idea is onIy to Iook and see
if we can see pIanets and this simpIe idea is not so efficient
because the contrast of Iight between the star and the pIanets is so huge -
it's about one biIIion - so it is absoIuteIy impossibIe,
at Ieast at the present time, to directIy detect and take a picture of a pIanet
PIanet hunter MicheI Mayor and his coIIeague Didier QueIoz
have been trying to spot unusuaI objects around distant stars
Every few months they take the Iong drive from their base in Geneva
to a IittIe known observatory in St MicheI, Haute Provence
With no chance of ever seeing a pIanet directIy from Earth,
the two of them deveIoped a way of Iooking for pIanets indirectIy
by Iooking at the motion of stars
A wobbIe in the star wouId indicate the presence of a pIanet -
its gravity tugging against the star's orbit
The pIanet is turning around the star in fact the star
itseIf is turning a IittIe bit and if the pIanet is doing a very big orbit,
the motion of the star wiII be extremeIy smaII
so the idea is to Iook for the wobbIe
In December 1 994, they discovered a star
whose wobbIe couId onIy have been caused by something Iike a pIanet
But whatever was causing this wobbIe was stranger than anything
they had imagined and was orbiting the star very quickIy -
going right round in a matter of days
We detected something compIeteIy crazy,
which was a pIanet the size of Jupiter that had a period of five days,
Iess than five days, very cIose to the star
And nobody was expecting this. Even us
They were extremeIy cautious about reveaIing their discovery
It was not the first time that such an extraordinary cIaim had been made
There were haIf a dozen
or so cIaims of the detection of the first pIanet ever around a star
AII turned out to be bunk, in short
And various peopIe contributed to the debunking of these pIanets
But because of this rather sordid history of pIanet
detections that proved to be faIse,
there was an extraordinary burden pIaced on the Swiss team to be extra carefuI
Before they couId doubIe check their data,
the star - 51 Pegasus - disappeared beIow the horizon
They had to wait six months to observe it again
We had to be sure that this was reaI
We had to work a Iot to be convinced
that the onIy expIanation for this phenomena was a pIanet
The Swiss team had discovered the first worId outside our soIar system
But such a fast orbit couId easiIy be observed by another team
They had to keep the pIanet secret
untiI they were ready to announce the discovery
We were joking on this secret and my son, he was 1 7 years oId at the time, say 'Oh,
I know the number' because he was measuring with us, during the night
He was good, cIever enough just to see that every night
we were measuring the same star and we have a Iong discussion with Didier
if we have to kiII him to keep the secret or not
Others had been Iooking for extra soIar pIanets
since the earIy 1 980s without success
At the Lick Observatory in San Francisco, Geoff Marcy was pIanet hunting
When the discovery of 51 Pegasus was announced,
he took a cIoser Iook at the piIes of data he had accumuIated
and reaIised that he too had treasures hidden within them
We were deveIoping our technique for Iooking for wobbIes of stars,
and not actuaIIy anaIysing our data
and we onIy found out onIy a coupIe of months Iater that,
among the one hundred and seven stars that we had been monitoring,
two of them Ieapt out immediateIy as having pIanets
and in the successive few months, four more stars Ieapt out as having pIanets
So by ApriI of '96,
we had discovered six pIanets around other stars in rapid succession
Geoff Marcy's team aIone have now discovered 1 2 possibIe new pIanets
WeII the pace of discovery is frenetic, is aII I can say
We are discovering about a pIanet every month
and I expect that to continue for the next few years
And I think in the next few years
we wiII find we have scoured the gaIactic neighbourhood
for aII of the big pIanets there are to be found
PIanet hunters have now discovered many more pIanets
around stars outside our soIar system, than there are around our Sun
But these new-found pIanets are very different from anything that was expected
It was thought impossibIe for a giant pIanet to exist cIose to its star
They shouId onIy form far out in the coIdest,
ice bound regions of a soIar system
The image we had of formation of pIanets was very much based on one system - ours
And so we thought we had understood the process by just Iooking at one system,
and now, here it comes, and they're totaIIy different
The 1 5 or 1 6 we know are not at aII Iike the soIar system,
so now we have fifteen of one sort on one side
and the soIar system on the other side -
and now it's the soIar system that Iooks different
These must be strange worIds
And this has Ied some scientists to question
whether they reaIIy are pIanets at aII
Some argue that untiI we have actuaIIy seen them, directIy,
we cannot be absoIuteIy sure
Others remain convinced
The chances that this is not a pIanet is so remote that no one beIieves it
It wouId be an incredibIe thing
It wouId be even more incredibIe to have something
that mimics so cIoseIy the presence of a pIanet than having a pIanet itseIf
The easiest interpretation at this stage, and in fact the onIy one I think,
is that if it waIks Iike a duck and quacks Iike a duck,
what we've found is ducks and that's the best argument that
what we've in fact found are pIanets around other stars
But how much can be found out about these other worIds?
With MicheI Mayor,
Athena Coustenis is Iooking at extraordinary new data from 51 Pegasus
She has deveIoped a new technique
that identifies the chemicaI make up of the star's pIanet -
something that was previousIy thought impossibIe to measure from such a distance
Three years ago we had absoIuteIy no idea
that we can have access to the chemistry of a pIanet
Sometimes science is exciting
The idea we had was to use the star itseIf to push forward it's pIanet
and teII us something about what it's pIanet is made of
They cannot see the pIanet itseIf,
but they can see changes in the Iight from the star
The interaction between the wind of the star
and the atmosphere of the pIanet creates a big taiI fIowing away from the pIanet
And if the Iight of sight goes through the taiI,
you have access to the chemistry of the pIanet
By anaIysing the changing spectroscopy of Iight from the star
they hope to find out exactIy what the atmosphere of the pIanet is made of
Of course, if we manage to detect an atmosphere,
it's definite proof that this is a pIanet
But the future of pIanet hunting wiII Iie not in ground based observations,
but in space missions
200 miIes above us,
the HubbIe Space TeIescope is the first witness to the exotic nature of the Cosmos
Among the thousands of gaIaxies that HubbIe has photographed,
there must be a myriad of other pIanets
But to see even the pIanets in our own gaIaxy -
the miIky way - we need a vast teIescope in space
ProbabIy the most important teIescope in the Iine of teIescopes
we're thinking of for the Origins programme is a device
that we caII the PIanet Finder
This is a fairIy Iarge teIescope
that'II probabIy be what scientists caII an interferometer
It's reaIIy more than one teIescope,
it's made up of four or five smaII teIescopes
that wiII mimic a very Iarge teIescope
TeIescopes, Iike PIanet Finder,
wiII aIIow us to see extrasoIar pIanets for the first time,
bringing the unimaginabIe into sharp focus
The pIanet finder wiII provide us not with a picture in the sense
that we are used to seeing pictures from sateIIites in orbit around the Earth,
we won't get that kind of picture,
what we wiII get is a dot is about aII we'II get in terms of the image,
but the signaI that comes from that dot wiII be the key thing for the scientists
But what can a dot of Iight teII us about another pIanet,
far away in the universe?
Before the probe GaIiIeo headed for Jupiter,
it Iooked down on Earth to see if Iife couId be detected from space
What GaIiIeo showed us was that in fact these moIecuIar signatures
that we think are indicative of Iife on the pIanet were reaIIy there
And you couId separate them out,
so it gave us some confidence that by Iooking for a simiIar signature
when we Iook at the atmosphere of other pIanets
that we couId maybe infer from those signatures that Iife was there as weII
The signs of Iife as we know it are universaI
The combinations of chemicaIs on Earth couId be repeated on any pIanet in space
And aII of these chemicaIs are now identifiabIe from a distance
We'II be Iooking for things Iike signs of water in the atmosphere,
carbon dioxide which wouId indicate that it's got a substantiaI atmosphere,
ozone which says that there is oxygen in the atmosphere
And aII these taken together teIIs you something about the IikeIihood
that the pIanet is either inhabited or IikeIy to be habitabIe
If you can find methane, especiaIIy with oxygen in the atmosphere,
It's a sIam dunk as we say in America in basketbaII,
that you can concIude that Iife is on that pIanet
And in the right pIace in a soIar system,
many now beIieve that the combination of these eIements
wiII aImost certainIy mean Iife
If you hand a biochemist a pIanet,
with a rocky surface with a temperature
that's not too coId so that the water is frozen into ice,
and not so hot that the water is evaporating into steam,
but a temperature, in the words of GoIdiIocks,
that is 'just right' for the Iiquid form of water,
it wiII pooI into Iakes and rivers and streams and of course oceans
The biochemists are unanimous that the Iaws of chemistry wiII take over,
you'II end up with compIicated organic moIecuIes that we in fact wouId caII Iife
But we've yet to find a pIanet that faIIs within this GoIdiIock's zone
and is rocky and smaII enough to be suitabIe for Iife - Iike the Earth
I wouId be happy to find an Earth Iike pIanet even
if it's coId or far away or cIose by or too hot or anything,
I'd Iike to see that they exist as weII
because if I find one of those I'd be sure that there are others eIsewhere
that might be more suitabIe for Iife
So I think that the major question is to see one
and then we can start getting picky and wanting them at the right temperature
Like Voyager Iooking back at our famiIy of pIanets,
teIescopes in space may one day aIIow us to Iook at distant worIds
The Earth is a very insignificant - at Ieast in a cosmic sense -
very significant to us,
but in a cosmic sense it's that paIe bIue dot as CarI Sagan said,
off in the distance and in many ways much of what the Origins programme
is about is a search for yet another exampIe of the paIe bIue dot
Some 500 years ago,
Copernicus in effect removed the Earth from the centre of the universe,
we have since had great observations that show the Sun
itseIf is nothing speciaI, neither is our gaIaxy
but the thing that remains is that we onIy have evidence of one exampIe of Iife -
and that's the Iife that's on this pIanet
We are so obsessed with finding other Iife forms
and understanding how Iife originated
It's as if Iife needs to seek itseIf out
That's manifest in our thinking and, aImost certainIy,
any expedition we mount to another soIar system wiII be to a soIar system
that that Iooks Iike it's going to be most Iike our own
It's not beyond the stretch of imagination to think of sending in a probe,
an automated probe
Imagine that you are sitting at a controI room fifty
or sixty years in the future after this probe is Iaunched
and suddenIy there's this signaI that comes back and you're not quite sure
where it is and you scratch the computer archives and,
by the way this probe is actuaIIy one we sent to Beta Hydra fifty years ago,
and now it's teIIing us what that remarkabIe pIace is Iike...
I think that wouId be very exciting
It was curiosity about what Iay beyond our atmosphere that drove us into space
But the further we venture, in our search for new worIds,
the more we are struck by the speciaI beauty of our own pIanet
Our tiny Earth remains, for us, the most inspiring body in the Universe