was a lot more full kind of activity than 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 and that can occur in the.

same district on tuesday does this is trucks in a san juan village by them ok no particular team in 1940 don't depend on the people had to move away it was a real catastrophe said to know the artist has made the volcano quite small to get the whole region was devastated where you're going yes it appears from nowhere in a cornfield with 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 volcanoes aren't inimical to life on the contrary they were necessary for life to develop throughout earth's existence to cooling stones at 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 with an explosion like that of ash may fall on surrounding villages forest and you guessed it so what's the gas made of a composite. say it's 95 percent water vapor in all ok nose around the world it's mostly water on a preserve all. the water vapor spat out by the volcanoes allowed 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 a life. full

point 4000000000 years ago thanks to the volcanoes earth sky changed filling with clouds. dilute the and rain started to lash the surface ukraine 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 age 2 well you need enough atmospheric pressure and atmosphere i mean on the moon there's no atmosphere so there's never a better you're left with water. 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 volcano has maintained enough of an atmospheric pressure for earth to be able to hold on. to

its early oceans. but the oceans of the young earth soon faced another danger that of 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 warm enough 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 su will be 2 months 6 a day of course we know that c o 2 increased by human activity is a bad thing too much as an good idea 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 i can back then with the sun younger and less bright it would have been much colder cougar earth would have been frozen but about minus 60 degrees so not favorable to life up of the side of. the volcanoes where yes 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 vapor. the c o 2 sat out by the volcanoes accumulated the greenhouse effect increased the ice melted and the oceans thought it could could we think this happened 400 or 500000000 years ago if you recall this period snowball earth in 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 like. 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 got out of control turning out planet into

a furnace. fortunately it was a safety valve c o 2 can dissolve in water. over millions of years 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 varies depending 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. backstrom of a fascinating thing about earth 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. it's like

a sort of geographical thermostat heating the earth always inhabitable with oceans on the surface is also 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 roll 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.

so unpleasant going at their life compunction you have to realize that the earth has a sort of crust of cold and solid rock on the inside there's a warmer rock the mantle which changes shape and all this is soft clear so you might imagine that the crust forms a solid complete shell like an egg shell around us softer and softer to see 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

growth smelt 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 most as sure it's a very particular geophysical thermostat which we think has really controlled the climate conditions on earth and made a life possible evolution lived. 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 in c o 2 concentration would have been different and the bias of yours would have evolved differently or.

see. if they are so petty little bags another important question a little secure this a plate tectonics just what seems to be the key the key to life on earth in the history there so it isn't like tectonic something really common in the rest of the galaxy angels and or something unique more very rare earth ha and that's all our system you don't find anywhere else in the black and i knew by your. 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 and also it was an environment of favorable to life obese 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 and 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 cup of d.c. i mean a big pot cools lower than the cup of tea which is mars as a guy that the inside cooled faster is south but there also there was no chance as we understand it for plate tectonics to arise. yeah you saw 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 there is something there after at the came 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 mass became red man was a victim of its own small size. and i was about all that there so you think the earth is just the right size so why is there no flame tectonics on venus which is the same size as earth why is that time one of the unlike earth has been is has hardly any water the water is all gone and

the mantle is very dry not very lubricated if you can't move much or displace any plates on the surface especially news 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 that you 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 standards. this is us you know this is the idea for the mantle. to have got sufficiently

hydrated sufficiently lubricated early in its existence earth suffered a huge cataclysmic and we think that the young earth was struck by another planet the size of mars which we call taya the young. a few tens of millions of years after its good that suffered a cataclysm which almost destroyed just how bright the chaos of the solar system's origins still reigned. in measure you know imagine a round earth hundreds of movements or dozens of the planet mars colliding repeatedly most of these objects grow in the form planet many 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 and then go to the med possible . thing crashed into

a the energy released by this enormous collision was equivalent to hundreds of billions of hydrogen bones. back that then won't you the impact is so violent that the impacting object is destroyed less fuel for the surface of the earth is completely liquefied 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. though. 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 the earth's mantle making it possible later for the plate tectonic system to function. as a species secular service but if it's right and it's impressive shows. that for life

to have existed on earth all this time that 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 moon. this is then down to the earth moon system is unique in the solar system and as far as we know in the galaxy system it's a very particular system where both objects are large objects this is why certain astronomers talk of a double planet but i'm led to go. 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. minister i pulled at the apollo missions placed reflectors on the moon surface now these reflectors are used today to reflect back laser beam as emitted from earth such as this one behind me and i while. there's a regular emission from here of the key. land plateau in the frat house phones.

today many observatories around the world like this one in the outdoor programs moment to the moon closely every night scientists use a laser beam to make a precise measurement of its distance from earth. as its balance and close up all 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 find out 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. for most of 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 acknowledge it's 380000 kilometers from earth but 4000000000 years ago we think it was only 15000 kilometers distant guns make you mad at them. that post immediately proximity of the moon had a 1st consequence of creating bigger tide and therefore maybe stimulating biological evolution to. the time it's 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 the rotational axis. they set their faces by something modern that the effect wasn't just the times it was much more that it's stabilized to the famous tilt on the angle of $23.00 degrees if i was worth a look at it as a built in relation to its trajectory around the sun will just. dave and this angle

has stayed constant for billions of years of media then it seems you knew me but i 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 this could have had huge consequences on evolution that fit with rapidly alternating periods of glaciation and warming for example long that all the less assume that although i shuffled. 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 peoples as its night the months.

show the mounds of mars phobos and deimos are so small that they play no stabilizing role on the rotational axis. and there have been a very big variations in the rotational axis of mars boss. what's more that's rotational axis has moved all around the surface of mars that's about it as off as ops. mons became a desert earth a garden of eden. and live like 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 and surely everything was perfectly set up for life to appear and evolve but earth still learns of 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 all getting the organic molecules of the basic elements necessary for life is are found in space already told or you are just in there already hold their leader right now some are 60 percent organic material which is you know and a lot still the earth. the original organic molecules which may have sown 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. jumpier be bring was one of the scientists behind the school day shift mission south is gone that was very good this is what we saw on the 14th of july 2014 when we got this we thought i suppose we can't land on that it's not feasible with us if this is tiny that particular method of the whole thing is only 4 kilometers and it's revolving around an hour after the fact that we 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 you have killed a few days here you see the lies leg and an object made just a few years ago and here the old is an 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 in a comet. with the 1st analyses the scientists realized that comets are very different from what they had supposed you know by neutral daughters of there's no water on this comet surface you know there isn't an ounce of ice we thought it was in the ice with a few molecules not at all i always see here is organic material for them at allegheny. thanks to the rosetta mission scientists discovered the 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 comets 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 end of the high up who was a 2 nation launched by the japanese space agency to bring back to earth a few fragments of this original organic matter. the

sample was collected in july and 29 team 300000000 kilometers from earth the mission was a success there in the mall this is the moment when it touched down the hallways he would pick it to see the leg touching down to a cell it's mind blowing out of work then you see it take off again for the president to call it the principle for taking samples as for it not to later it is all it touches down was on the wires of all edges 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 that they are still. us like i said it's completely mind blowing we hope that in a sample there's carbonaceous material from which we think well life on earth began appearing. 1 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. say 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 that 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. back.

last. cinema should be celebrated since had recently had its 125th birthday. but the movie industry is in a crisis which has been exacerbated by corona. will the movies ever be the

same and if so when are $21.00. and 30 minutes on d w. it's about billions. it's about how work. it's about the foundation of a new world order the new silk road. china wants to expand its influence with this trade network. but in europe there's a sharp morning whoever accept money from the new superpower will become offended john mccain if. the chinese state has a lot of money at its disposal of books and that's how expanding and asserting its status and position in the world. china's gateway to europe.

starts feb 19th on d w. this is d.w. news live from berlin the closing arguments are underway in the 2nd impeachment trial of former u.s. president donald trump trial resumed after democrats and republicans agreed not to call witnesses but leader mitch mcconnell's intention to vote for a clip means trump is unlikely to be found guilty of inciting violence. also on the

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