kind of captivity even today. so michael i mean i'll bow out when you 1st think about a volcano you think of lava danger and life threatening eruption but volcanoes were essential for life as we know of you at that clinic when they.

said destruction on duty does this is trucks in a san juan village by them ok no particular team in 1904 you don't want to bet the people had to move away it was a real catastrophe sits in the artist has made the volcano quite small to get the whole region was devastated to where you're going to live here from nowhere in a cornfield was that all no one could have expected it when the village was destroyed that it was still quite small but take all. you would call some balk a nose aren't inimical to life on the contrary they were necessary for life to develop throughout earth's existence to cool things down to let them.

what else are such explosions common in they happen but not that often i've been here 6 years and i've seen 4 o'clock with an explosion like that of ash may fall on surrounding villages forest and you guessed it so what's the gas made of composite . say it's 95 percent water vapor in all ok nose around the world it's mostly water there was only a preserve all along. the water vapor spat out by the volcanoes allow the water trapped in the earth's balance to make its way to the surface. this has always been an essential mechanism for keeping our planet hydrated and alive.

4.4000000000 years ago thanks to the volcanoes earth sky changed filling with clouds. dilute the and rain started to lash the surface it rained for millions of years and the 1st oceans formed. yet barely had they appeared then they could have just as quickly evaporated. skittish seems the difficult bit is having liquid water similarly you don't just need h 2 well you need enough atmospheric pressure most an atmosphere on the moon there's no atmosphere so there's another benefit you look at what you want to do. if the earth's atmosphere hadn't been dense enough the water would have evaporated into space in the form of vapor. fortunately the gas produced in abundance by the volcanoes maintained enough of an atmospheric pressure for earth to be able to hold on to its own. the oceans. but the oceans of the young earth

soon faced another danger that the freezing over. the sun was still weak 30 percent less bright than it is now earth therefore needed a greenhouse effect to keep its surface woman off and its water in a liquid state. this greenhouse effect appeared very early on in earth's history thanks to the water vapor and c o 2 abundantly present in the atmosphere of ash will be announcing today of course we know that c o 2 increased by human activity is a bad thing too much as and good but we needed some back then and still do if there wasn't a bit in the atmosphere the surface temperature would be 15 degrees colder can in fact then with the sun younger and less bright it would have been much colder beaucoup earth would have been frozen about minus 60 degree sun so not favorable to life appleby said of. the volcanoes we yet again contributing to

making earth habitable in their x. aleisha as they would constantly spewing out huge quantities of c o 2 along with the water they. pursued the c o 2 sat out by the volcanoes accumulated the greenhouse effect increased the ice melted and the oceans thought we think this happened 400 to 500000000 years ago we call this period snowball urge and the earth emerged from it like that if it's in the greenhouse effect increased and we got back a climate with liquid water favorable to likely be sellable. but with the constant eruptions the c o 2 from the volcanoes was steadily accumulating in the young earth's atmosphere the greenhouse effect. could have gone out of control turning our planet into

a furnace. fortunately it was a safety valve c o 2 can dissolve in water. over millions of years and it's trapped in calc areas formations and no longer acts as a greenhouse gas he remains trapped you know at the bottom of the ocean in mineral form. the quantity of c o 2 in the atmosphere then a very stupid ending on the amount of liquid water on earth's surface. over a very long time scales this make an ism regulates our planet's climate. fascinating thing about or which may make it unique is that all through its very long existence all 4 and a half 1000000000 years variations in the luminosity of the sun have been compensated for by a variable greenhouse. and if it feels. like a sort of geographical thermostat keeping the earth always inhabitable with oceans

on the surface will still want to show us. but this thermostat needed one more tweak to get it working perfectly and make our planet truly favorable to life. over hundreds of millions of years but the c o 2 in the atmosphere could have ended up trapped in the form of count carious wrong at the bottom of the ocean. they wouldn't have been enough in circulation to keep the thermostat going and it would have broken down. a mechanism possibly unique to our planet allowed for the reinjection of c o 2 into the atmosphere plate tectonics. thanks.

going at them for the compunction you have to realize that the earth has a sort of crust of cold and solid rock really auspice inside there's warmer rock the mantle which changes shape and all this is soft coup so you might imagine that the crust forms a solid complete shell like an egg shell around a softer inside sympathy but that's not right the movements of the shifting rock on the inside were powerful enough to rub up against of the crust and a crack in the places where. the earth's crust is fragmented into 10 plates which are displaced by the movements of the mantle. where the plates come together they crunch over each other dragging the rocks that were at the bottom of the ocean deep into the bowels of the earth dust just the c o 2 recycling begin. under the enormous pressure and heat the

rocks melt and the magma is spewed back out onto the surface taking the c o 2 with. the c o 2 escape seen gas form during volcanic eruptions finally back in the atmosphere the c o 2 may or may not be captured again by the oceans depending on climatic conditions the circle is complete. sometime with the show it's a very particular geophysical firmest that which we think has really controlled the climate conditions on earth and made a life possible. to see if you changed in the plate tectonics just a little having slightly more or fewer than 10 plates and then with the recycling it's the ultimate concentration would have been different and the bias here's what evolved differently or.

just see. if they yes so petty little bags another important celestial felt secure this a plate tectonics just what it seems to be the key the key to life on earth the latest you're there so it isn't like tectonic something really common in the rest of the galaxy angels and or something you mean were very rare to high up in that solar system you don't find it anywhere else in the black you know new behavior. plate tectonics maybe the fact which earth's neighboring planets lacked for life to appear on and survive then. yet one of the solar systems on the rocky planets did get off to a good start early in its history with volcanoes c o 2 and. enjoyed an environment similar to earth's.

i don't know if you so there was an environment imagine a blue mars with lakes and rivers up on something there was an ocean in the northern hemisphere it also it was an environment of favorable to life of peace and i think. all would seem to have been set up then for the planet to function in a similar fashion the current state of the red planet however clearly shows that something went wrong. so most young mars cooled down much faster that i disagree massive events mars is half the size of earth and it's a bit like comparing a huge pot of hot water to a couple of d.c. i mean those folks have a big pot of cool slower than a cup of tea it was just mars as a guy that the inside cooled faster is sat back down so there was no chance as we understand it for plate tectonics to arise. by you so if there was no recycling

that could maintain a climate favorable to the oceans for billions of years mars had hundreds of millions of years and then there after it became a very sterile planet and it pristine. masses tragedy is that it's too small and fell into a deadly spiral because of its small amounts there was insufficient gravity to hold on to its atmosphere the drop in atmospheric pressure was inexorable and the solar wind swept it all away some of the water evaporated the rest froze blue monster became red man was a victim of its own small size. i was about all there so you think the earth is just on the right size so why is there no plate tectonics on venus which is the same size as earth cause us why is that time one of the unlike earth has been as has hardly any water the water's all

gone and the mantle is very dry not very lubricated if you can't move much or doesn't place any plates on the surface especially when you're so venus has a sort of unbroken shell all around the planet it doesn't have the mechanism that earth so it's not just important to be the right size but to have water in the mantle and that of all the really don't want to. earth has enough water to lubricate its plate tectonics venus doesn't and yet the 2 planets were formed from the same materials. one very special event during earth's youth could have hydrated its depths. this is us you know this is the idea to it for the mantle to have got. sufficiently

hydrated sufficiently lubricated early in its existence earth suffered a huge cataclysmic we think that the young earth was struck by another planet the size of mars which we call the young. a few tens of millions of years after its good then suffered a cataclysm which almost destroyed just how bright the chaos of the solar system is origins still reigned. imagine imagine a round earth hundreds of moons or dozens of the planet mars colliding repeatedly these objects grow in the form planet maybe planets. if you suddenly an object the size of mars comes towards our earth and crashes into the surface at a speed of something like 15 kilometers per 2nd act on the nuclear med possible.

thing yet crashed into a the energy released by this enormous collision was equivalent to hundreds of billions of hydrogen bombs. back to the movie impact is so violent that the impacting object is destroying less fuel for the surface of the earth is completely liquified and the core of the impacting body penetrates the earth's mantle and it's becoming part of the earth's core we think the earth's core fused with that of the impacting body. the collision was so violent that the water contained in was driven deep into with school mixing with the water already present there in this way they are hydrated the depths of earth's mantle making it possible later for the plate tectonics system to function. as a species speculative us but if it's right and it's impressive it shows us that for law. i have to have existed on earth all this time but we needed that chance impact

a very early in earth's history to hydrate the mantle and maintain its lubrication and have this phenomenon this geophysical thermostat all throughout the planet's existence would have been at. least seeming catastrophe would end up being beneficial in another way as earth gained a new companion which would play a major role in the blossoming of our ecosystem out of the cloud of debris resulting from the collision a new body would gradually form the move. to . resist them down in the earth moon system is unique in the solar system and as far as we know in the galaxy is that it's a very particular system where both objects are large objects this is why certain astronomers talk about double planet but i've got.

barely had it come into existence than the moon was already exerting a powerful influence over the earth because of its considerable size. the history of the earth moon relationship has been studied very closely thanks to the apollo missions. or. minister or pulled in the apollo missions placed reflectors on the moon surface now these are factors are used today to reflect back laser beams emitted from earth such as this one behind me i while. there's a regular emission from here at the color i'm glad. so and the friends that i

phones. today many observe the trees around the world like this one in the. morning to the moon closely every night scientists use a laser beam to make a precise measurement of its distance from earth. so this balance will close up on these are important experiments because we can measure how long it takes the laser beam to go to the moon and back. so we can measure in real time the distance to the moon. and one major findings which we sort of knew before but are now sure of is that the moon is moving away in a way it's moving away at a speed of 3 or 4 centimeters per year ready. these measurements have shown that when it formed the moon was much closer to the earth than it is today to a platform as well that is soon after the moon formed if anyone had been here to

see the moon it would have been gigantic in the sky because it was so close to them said it was going to the canal it's 380000 kilometers from earth but 4000000000 years ago we think it was only 15000 kilometers distant doesn't make you mad at them. that you need any proximity of the moon had a 1st consequence of creating bigger tide and therefore maybe stimulating biological evolution to. the tom nides caused by the moon churned up the oceans and contributed to the dynamism of our ecosystem the mutual attraction between the 2 bodies also had a crucial effect on me it's rotational axis. it had to face about something more than what the effect wasn't just the tide it was much more to that effect that it's stabilized to the famous tilts on the angle of $23.00 degrees i was worth a look at this is a built in relation to its trajectory around the sun would you say. and this angle

has stayed constant for billions of years i mean yeah then it seems you know we both knew no dollar that if the moon hadn't been there the earth's rotational axis would have oscillated causing rapid changes in the climate and this could have had a huge consequences on evolution that with rapidly alternating periods of glaciation and warming for example long that all the less assume that although i shuffle. the moon helps the earth maintain a climate stable enough for the slow and gradual evolution of life. was. without the moon the earth would have been faced with the same up evils as its neighbor among us.

the mounds of mars phobos and deimos are so small that they play no stabilizing role on the rotational axis. yeah i mean there have been very big variations in the rotational axis of mars afs. what's more that's rotational axis has moved all around the surface of mars so badly as far as ops. months became a desert earth a garden of eden. we need the present earth moon system is the result of a long series of accidents making the earth and moon a unique couple in each. earth

now had a stable climate and atmosphere and liquid water surely everything was perfectly set up for life to appear and evolve but the earth still lacked to the basic ingredients of life organic molecules. all living things on earth are made of the same building blocks long carbon based molecules scientists now think that a large proportion of these molecules came from outside the planet earth. limerick you are on any of the organic molecules or the basic elements necessary for life is are found in space only hold on to your destiny are already whole their leader writes some are 60 percent organic material which is you know and a lot still to earth. the original organic molecules which may have sown in the seeds of life on earth were

present in the distant cold zone of the solar system but how did these building blocks of life travel to our planet the rosetta mission the 1st to ever attempt landing a module on a comet shed some light on this mystery. shown here be bring was one of the scientists behind this all dangerous mission ses go on that was very good this is what we saw on the 14th of july 2014 when we got there we thought why should i suppose we can't land on that it's not feasible with us that this is tiny that particular method of the whole thing is only 4 kilometers and it's revolving around an hour after that i thought i would thought we'd never find a spot to stand down it was crazy so it covered more for. a few months later the probe feel a managed despite all the difficulties to touch down on the comet cheery.

always hear a kid if you know if you're using the lies leg and an object made just a few years ago and here the oldest object in the solar system the same as when it formed 4600000000 years ago it was the 1st time and it will happen again so that we set something down on a comet. with the 1st analyses the scientists realized that comets are very different from what they have supposed you have value to a go at us for there's no water on this comet surface you know there isn't an ounce of ice we thought it was and the ice with a few molecules not at all always see here is organic material for that matter are getting. thanks to the rosetta mission scientists discovered that comets are abundant in the building blocks of life. up until then they had thought that only asteroids little rocky

bodies with us in doubt. since the birth of the solar system comets and asteroids have gravitated in the colder regions where they capture and store these original organic molecules. then these comments and asteroids veritable messengers of life transport these molecules into the inner zones of the solar system. as they pass close to a planet they disseminate these building blocks on to the surface providing it with the wherewithal for life. scientists are keen to undertake laboratory analysis of organic molecules similar to those which fell into earth's oceans this was the aim of the higher who's a 2 mission launched by the japanese space agency to bring back to earth the few fragments of this original organic matter. the sample was

collected in july 29 teams 300000000 kilometers from earth the mission was a success and in the mall this is the moment when it touched down the hallways he would take you to see the leg setting down there you know i thought it's mind blowing over a problem then you see it take off again to proceed according to the principle for taking samples as for it not to linger in this song it touches down all of the fires of all ages and leaves again with the debris that the guy it takes a few seconds with us and it all happens very far from earth of course at their heels you're. a slave i think it's completely mind blowing we hope that in a sample of this carbonaceous material from which we think well life on earth began appearing. in the probe is bringing back a 10th of a gram of these precious building blocks of life similar to those which landed on

the planets of our solar system some 4000000000 years ago. a population at the euro from this material we want to find out what the initial ingredients were in the waters of earth primordial oceans and all you made possible the great chain of terrestrial biology your asian guys talk. comets and asteroids could be the missing links of a long chain the chain began with the simple molecules found in the early cloud dusts and culminated with the building blocks of life from which life on earth 1st sprang the chain leading to life.

last. to the point of strong opinions clear positions international perspective such. things are getting increasingly strange between the e.u. and china the 2 sides have been hoping to sign a landmark investment deal in reality though that hardly on speaking to us why find

out only to the point shortly. to the point of. even 90 minutes on d w. d beethoven in favor of jazz did to did do. did is it was a dud is 16 my g.p. to. assume any romance of stolen beethoven. would of course the subconscious always one thing is clear the beethoven just wildly popular. i see a sure shot i love you sure. but how would the world sound without the biggest composer of all time i can't even begin to imagine a world class horn player senlis on a musical journey of discovery. without

a token. this week on. business d w news live from berlin israel's preparing to return to lock down the country will be the 1st developed nation to enter a 2nd lockdown is being met with protests in tel aviv or new prescriptions will be going into effect as the jewish new year begins later today also on the show. fears over a 2nd wave of infections in germany the country has recorded the highest daily number

of new cases since late the government's top rolla just tells the wu that good communication with his crew.