good evening ladies and gentlemen how are you all doing so uh if i'm not mistaken you've written a few some messages last week and you are writing a few this week as well i'm also doing fine thank you so are you awesome tests going so far it's a good hectic so mixed feelings so did anyone watch the lunar eclipse this morning so you at those stats watch the eclipse how was it i also skipped this one loon eclipses are usually amazing but loon eclipses is actually quite a common phenomenon there's a few actually happening per year so it's uh the eclipse this morning its maximum was just before six o'clock so let's start with tonight's lecture so in last week's lecture we started to discuss the different effects that we have on global warming and how global warming and climate change is all around us have you guys literally noticed climate change in your everyday lives okay so what is the effects that you guys have already started seeing so yes it's raining in may so the weather cycle is messed up yes we have flooding certain microclimates will change that means the certain parts of africa certain climates will be warmer and certain places will also be a lot colder you have a palm tree that's blossoming now okay that's interesting victoria weaver strange number one yes that's all to do with global warming so let's begin so yet another misconception is that the observed warming of earth is due to natural causes rather than the greenhouse effect as scientists began to study early indications that earth's global climate is warming and that human humans produced co2 might be a major cause they have reacted with professional skepticism they're asked questions such as is global warming really happening and if the warning is real there's some mechanism other than human activity the main cause experiments were conducted calculations performed and models created to answer those types of questions such research carried out over decades revealed that the regular and predictable changes in earth's axis inclination and orientation in the shape of its orbit called the language cycle currently would be driving earth's climate towards lower not higher temperatures also observations by space probes indicate that a sun's luminosity average over its activity cycles has been constant for decades or has decreased slightly the observed warming must be strong to be occurring in the face of opposing astronomical effects so uh what is what is the scope of our semesters next week so i will give the scope to you guys tomorrow so the amount of warming to expect in the future is difficult to predict because earth's climate is critically sensitive to a number of different factors not just abundance of greenhouse gases for example a slight warming should increase water vapor and atmosphere and although water vapor is enough another greenhouse gas that will enhance the warming increased water vapor might cause add cloud cover increasing earth's albedo the fraction of light it receives that is reflected back to space an increased albedo would be thing to reduce the warming also even small changes in temperature can alter circulation patterns in the atmosphere and in the oceans and the consequence of such changes are very difficult to model the situation is complex but models that best track the warming that has already happened point to substantial continued warning there's no doubt that civilization is warming earth through an enhanced greenhouse effect but the remedy is difficult to imagine reducing the amount of co2 and other greenhouse gases released to the atmosphere is difficult because modern society depends on burning fossil fuels for injury political business and economic leaders may argue that issue is uncertain but all around the world scientists of stature have reached an agreement global warming is real is driven by human activity and will change earth what humanity can or will do about it is uncertain human influences on earth's atmosphere go beyond the greenhouse effect our modern industrial civilization is also reducing ozone in earth's atmosphere many people have a common misconception that ozone is bad because they hear it mentioned as a pollutant of city air produced by electro emissions breathing ozone is bad for you but as you learned early in this chapter the ozone layer in the upper atmosphere protects the lower atmosphere and earth's surface from harmful solar uv photons ozone is an unstable molecule certain chemicals called chlorofluoro chloro fluorocarbons cfcs used for refrigeration air conditioning and some industrial processes can easily destroy ozone as these cfcs escape into atmosphere they become mixed into the ozone layer and convert ozone back to normal oxygen molecules ordinary oxygen does not block ultraviolet radiation so depleting the ozone layer causes an increase in ultraviolet radiation at earth's surface in small doses ultraviolet radiation can produce a sun turn but in large doses it can cause skin cancers the ozone layer is especially sensitive to cfcs over the antarctic and arctic regions because of the temperatures starting in the late 1970s the ozone concentration fell significantly over the antarctic and a hole in ozone layer developed over the continent each october at a time of the antarctic spring satellite airborne and ground-based measurements showed the same thing being to happen at a far north latitudes with the amount of ultraviolet radiation reaching the ground increasing fortunately as a result of these warnings international agreements banned most uses of cfcs and a trend of ozone hole expansion slowed and now appears to have reversed in image a we can see satellite observations of ozone concentrations of antarctica are shown here as rigged for high highest concentration and violet for lowest starting in the 1970s a hole in the ozone layer was observed to develop over the south pole did an image be although ozone depletion is most dramatic above the south pole ozone concentrations have declined at all latitudes there is yet another misconception that global warming and ozone depletion are two names for the same thing take careful note that an ozone hole is a second earth environmental issue that is basically separate from global warming the co2 and ozone problems in earth's atmosphere are paralleled on venus and mars when you study venus in chapter 17 you will discover a runaway greenhouse effect that has made the surface of the planet hot enough to melt lit also in chapter 17 you will learn that mars has an atmosphere without an ozone layer a few minutes of sunbathing on mars would kill you once again you can learn more about your own planet by studying exaggerated conditions on other planets so yes i think you are correct in the fashion i heard it almost uh closed up again or could be closed up right now again the ozone layer so yeah you can go through these slides in your own time but this is how earth got a nice summary of earth and the moon and how the two compares to one another so now we're gonna start so let's go back one slide so now we're going to talk a little bit about the moon and i'm just assuming with your assignment you guys can tell me some pretty cool things about a moon david moves what else do you know about the moon what interesting facts do you have about a moon or what have you learned about them in your assignment so far yes ma'am are you correct it's slowly drifting away my finger rate is about one or two centimeters from there yes the moon shifts 12 to 13 degrees every night in position so isn't a problem that's moving away so due to um the gravitational force of the attraction between the moon and earth yes it's decay of gravity it's moving away so it's not a problem it's still going to be here for billions of years but it's moving away at a rate of between one and two centimeters per year and in astronomical terms that is insignificantly small so if you had been one of the first two people from earth to step onto the air surface of the moon what would you have said neil armstrong responded to the historic significance of the moment by saying that's one small step for man one giant leap for mankind whilst aldrin was second and he responded to the moon itself saying beautiful beautiful magnificent desolation in other words although it is desolate the moon has its own kind of beauty many planets in the universe probably look like earth's moon and astronauts may someday walk on such worlds and compare them with earth's moon only 12 people have stood on the moon but planetary astronomers know it well the photographs measurements and samples brought back to earth by the picture of an ancient battered crust and a world created by a planetary catastrophe the surface of the moon is divided into two dramatically different kinds of terrain the dark gray areas visible from earth by naked eye are the smoother lunar lowlands which using the latin word for seas early astronomers named maria plural of may which is please um because produced easter is not made that's english bronx action so latin branch nation is mare you can also see the comparatively bright rugged and heavily created lunar islands the color of moon rocks is dark gray but earth's moon looks quite bright in the night sky in fact the average albedo of earth's moon so the fraction of the light that reflects is only one 0.12 so in other words the moon reflects only 12 percent of the light of the light of the sunlight that hits it in comparison earth thanks mostly to its bright clouds has an average albedo of 0.31 the moon looks bright only in contrast to the night sky in reality it is a dark grey world whenever you look on the moon you find craters these craters look quite dramatic near the terminator the name for the boundary between daylight and the darkness on the moon where shadows are long as you have already learned the islands are heavily marked by craters whereas the smooth lowlands contain a relatively few craters planetary scientists now know that the craters on the moon were formed by the impact of meteorites study notice three important points by last five new terms one impact craters have certain distinguished characteristics such as their shape and the injector rays and secondary craters around secondly lunar impact craters range from tiny pits formed by micro meteorites to dry and multi-treated basins and in thirdly most of the craters on the moon are old they were formed long ago when a solar system was young 12 apollo astronauts visited the luna lowlands and highlands between 1969 and 1972 most of the rocks they found were typical of hardened lava and some were the circular basils which contains holes formed by bubbles in the molten rock these bubbles are made when lava flows out onto the surface and the lower pressure allows gas to dissolve in a molten rock to expand and form bubbles the same thing happens when you open a bottle of carbonated beverage and bubbles form the presence of the circular vessels shows that much of the surface of the moon has been covered by successive lava flows in the dark flat plains of the lunar lowlands the moray or maria are actually solidified ancient lava the islands in contrast are composed of rock containing minerals that have low density and would be among the first to solidify and float to the top of the molten rock for example the highlands are rich in another site a light-colored low-density rock that contributes to the highlands bright contrast with the dark lowlands apollo 11 the first mission to the moon landed on a smooth surface of the mayor tranquilities lunar lowlands and the horizon was straight and level when apollo 17 landed at taurus lito in the lunar islands the astronauts found the horizon mountainous and the terrain rugged the large boulder is a piece of ejector that at some time in the past were thrown here from impact far behind the horizon rocks returned from the moon showed that a moon once had a deep magma ocean of molten rock that after the surface solidified it was heavily fractured by cratering and that had now affected mainly by micrometeorites grinding away at surface rock many of the rocks all over the moon are brickies a rock made of fragments of broken rock cemented together under pressure breakers show how extensively lunar surface has been pounded by meteorites nowhere that astronauts find what we called bedrock the entire surface of earth's moon is fractured by meteorite impacts moreover the astronauts bobbed across the lunar surface under its low gravity the boots kicked up the powdery dust this lunar dust is produced by the continuous bombardment of the lunar surface by tiny meteorites that slowly grind exposed rocks into fine grained grit with a consistency like talcum powder the lc ross a lunar crater observation and sensing satellite mission discovered that at least in one permanently shared region in the moon south pole there is a significant amount of water ice under the surface dust layer over the last two centuries astronomers developed three different hypotheses for the origin of the moon the fission hypothesis produced that a moon broke from a rapidly spinning young earth the condensation hypothesis suggests earth and the moon is condensed from the same cloud of matter in the solar nebula the capsule hypothesis suggests that a moon formed elsewhere in the solenoid and was later captured by earth evidence of these ideas had problems and failed to survive comparison with all the evidence in 1970s based substantially analysis of newly available unirock samples a new hypothesis originated that combined some aspects of the free old hypothesis the large impact hypothesis proposed that a movement formed when a very large planetesimal estimated to have been at least as massive as mars smashed into the proto-earth such a collision would have ejected debris into space and model calculations indicate that some of the debris would have settled into a disk in orbit around earth the material in the disk would then have quickly collected to form the moon so the moon was made when a mars-sized planet eat earth is that not right so yes that is true so here we can see an image of it so the proto-earth differentiated to form an iron core another body about the size of mars that had also formed an iron core struck the proto-earth and merged with it trapping most of the combined iron inside an iron poor rock from which the mantles of the two bodies formed a ring of debris volatiles were lost to space as the particles in the ring began to accrete into larger bodies and then eventually the moon formed from the iron poor and volatile poor matter in the disk this hypothesis display explains several phenomena if the collision occurred off center it would have spun the earth moon system rapidly and would just explain the present-day angular momentum if the proto-earth and an impact had each already differentiated the ejecta material that became the moon would have been mostly iron poor mantle and crust which would explain the moon's low density and iron poor composition furthermore the material would have lost its volatile components while it was in space cinnamon also would have formed lacking in volatiles as much as was noted in the apollo rock samples such an impact would have melted the preservative and a material falling together to form the moon would also have been heated hot enough to melt this fits the evidence that a highland an oversight in the moon's oldest rocks formed by differentiation of large quantities of molten material the large impact hypothesis survives comparison with the other evidence and is now considered likely to be correct so it is unsettling to think that once the earth was also desolate rock no different from any other restaurant disabled yes that is true and that is the point that we're going to discuss in the last chapter of this module so the four stage history of earth's moon is dominated by a single fat that makes unfolding noticeably different from earth's history and the later stages the moon is small only one fourth diameter of earth its escape velocity is low so the moon has been unable to hold any atmosphere it cannot have surface water and its interior cooled rapidly as its internal heat fed outward into space small walls have less heat and lose it near rapidly so the moon's small size has been critical in determining its history the apollo moon rocks especially an oversight from the highlands share that the moon must have formed in a molten state planetary geologists now referred to the exterior of the newborn moon as magma ocean so magmar zone for molten rock in general whereas lava means molten rock flowing on the surface of wood denser material sand to the bottom of the magma and as the magma cooled loadings and minerals floated to the top to form a low density crust in this way the moon partially differentiated so a question that he dissipated from the moon in the form of light energy so no it would have been dissipated in a form of thermal energy the radioactive ages of moon rocks brought back by apollo astronauts showed that a surface solidified about 4.4 billion years ago the second stage cratering began as soon as the crust solidified and all the islands showed that cratering was in things during the bombardment period at the end of planet building the moon's crust was shattered and the largest impacts form giant multi-ringed crater basins hundreds of kilometers in diameter the basins that became moire iberians a sea of raisins for instance was blasted outbreaking back of an object about the size of rhode island this imbrium event occurred about four billion years ago and blanketed 16 of the moon with rejecter so question but the moon is in a vacuum of space so the heat wouldn't have a medium to transfer yes it will so you can still use the space remember black body radiation so even space it's not a true vacuum it's just less particles but space itself has a temperature uh black body radiation as mr marvel said so yes it will still radiate into space so i'm sure thermal energy is a fancy word for light energy so not really so some thermal properties so some objects for example a candle flame radiates energy in heats of thermal energy but it will also radiate energy away in terms of light so depend on what is happening but it can be both but in case of the moon it is usually thought about as a thermal injury because we speak about light energy the moon doesn't create its own light so the injury speaking about is thermal energy so near the end of the heavy bombardment a giant impact created the vast crater basin faulting in the crust producing rings of mountains and lava flows filled the low regions today all by the outlines of the impact have been covered by dark lava flows by counting craters on different parts of the moon and calibrating those data using radioactive ages of lunar rock samples planetary scientists have been able to chart the decline of cratering over the first billion years of the solar system's history by about 3.8 billion years ago the impact rates had decreased to the current low rate but before that there seems to have been a sudden burst of cratering astronomers called the latent bombardment that might have included the imbrium event the primary evidence of this late bombardment comes from observations of the moon but that sudden storm of impacts must have affected all of the planets in the solar system including earth those craters on earth were were erased long ago but they can be seen on other worlds such as mercury mars and some of the moons in the outer solar system to understand what astronomers think caused the latex bombardment you'll need to learn more about the formation and evolution of uranus and neptune in chapter 18. can calculate that tremendous impacts that form the lunar basins would have cracked the crust in depths of 10 kilometers or more and led to the third stage flooding through earth's moon cooled rapidly after its formation radioactive decay continued to eat the lunar subsurface material as it did inside earth parts of the lunar mantle and lower crust re-melt the producing lava that followed the cracks up into the drying basins the basins were flooded by successive lava flows of dark vessels from 3.8 to 3.2 billion years ago thus forming the moire so in this image we can see much of the near side of the moon is marked by large generally certainly larval planes called moire the crust on the far side is thicker and there is much less flooding even the used south or aiken basins contains level of flooding in these maps color marks elevation with the red the highest regions and the purple the lowest studies of the moon show that its crust is thinner on the sideboard as a side towards earth perhaps the eutectic effects consequently will lava flood the basins on the earthwood side it was unable to rise through the thick crust to flood the lowlands on the far side one of the largest known impact basins in the solar system is the moon south pole aitkin basin it's about 2 500 kilometers in diameter and as deep as 13 kilometers in places but flooding has never filled it with smooth lava flows to make an obvious moire the fourth stage slow surface evolution has been more limited on the moon than on other than on earth because the moon has cooled rapidly and also lacks water flooding on earth included water but the moon has never had an atmosphere and this has never had liquid surface water with no air and no water the erosion is limited to the constant bombardment of micrometeorites and very larger impacts as the moon lost its internal heat volcanism died down and the moon became geologically dead so question are all these conclusions made using simulations via computer or using photographic evidence am i wrote both are used to conclude how the moon was formed yes both are used so we actually study them moon so you've got the moon rock itself you measure the craters and then you use those data or the analysis you made on the moon and you create the mathematical model and then from the mathematical model you create a simulation and then from simulation you can determine what is going on but first it's like we discussed in the opening chapter we need to get data so we observe the moon we gather data from the moon then from what we observe we create a mathematical model and from a mathematical model we create a simulation from simulation we have an idea of what's going on its crust may be divided into moving plates even from the fact that there are no folded mountain ranges and the moon is now a one-plate object frozen between stages three and four so here we can look at practicing science so if the moon was intensely created by the heavy bombardment and then formed great lava flames why didn't the same thing happen to earth so even though the answer to this question seems obvious scientists still review the logic to test their understanding of basic concepts in fact the same thing everybody's cratering did happen on earth although the moon has more craters than earth the moon and earth are the same age and both were battered by meteorites human some of those impacts on earth must have been large and dark giant multi-ringed basins lava flows must have weld up through earth's crust and flooded the lowlands to form great lava plains much like the lunar moire earth however is larger wall and has more internal heat which escapes more slowly than a moon's heat fit the moon is now geologically dead but earth is very active with heat flowing outward from interior to drive blade tectonics the moving plates long ago erased all evidence of the cratering and lava flows dating from earth's youth comparative planetology is a powerful conceptual tool in that it allows you to see similar processes occurring under different circumstances now employ comparative anthology to explain different phenomena and then what all one of the most fascinating aspects of science is its power to reveal the unseen that is it reveals regions you can never visit you saw this in earlier chapters when you study the inside of the sun and stars the surface of neutron stars they even derives around black holes the cause of active galaxies and more in this chapter you have seen earth score and engineers person builds things so you can call a person imagines things imagine most creatures on earth cannot imagine situations that do not exist but humans have evolved the ability to say what if our ancient ancestors could imagine what would happen if a tiger were hiding in the grass and we can imagine the inside of the earth a poet can imagine the earth the heart of the earth and a great writer can imagine a journey to the center of the earth in contrast scientists use the imagination in a carefully controlled way guided by evidence and theory they can imagine the molten core of our planet as you read this chapter if you saw the yellow orange glow and felt the heat of the liquid iron then you were a scientific imaginer human imagination makes science possible and provides one of the great thrills of science exploring beyond the limits of normal human experience and that ladies and gentlemen is the chapter about the earth and the moon any questions no questions everyone's still awake okay cool so mr marvel i still need to get back to you on that question can you guys guess what is the next spot so the next part we are going to discuss is mercury venus and mars so what can you tell guys tell me about mercury venus and mars okay the other racial words that's correct could earth have more than one moon so our earth and our own moon formed earth only have one moon but yes there are planets that have more than one moon secret there are other terrestrial planets moss have does they can have dust tables yes they are neighboring planets yes do you know what this is could have had more than one before we existed unfortunately not so our earth and moon formed is we only have one moon so mr swanopool swannapul does they will in afrikaans as environment so can you guys recognize this image of what this is no so this is a close-up image of mercury so yes mr joshua you are correct this is mercury so this picture was taken by one of the solar probes that visited mercury and what is this yes this is venus and this one yes this is mars in a previous chapter you compared a geologically active planet of the largest of the racial worlds with the smallest earth's geologically inactive moon in this chapter as you continue studying individual terrestrial planets you can continue comparing the planets with each other searching for similarities and contrasts like people the terrestrial planets are more alike than they are different but it is the differences that are most memorable so a question i was told to tell you that uh brendan from the city have some connection issues but we'll watch recordings later that is no problem thank you for informing me mr marvel so as you explore you will be searching for answers to four important questions firstly how is mercury similar to and different from earth's moon secondly how does distance from the sun affect the planet and its atmosphere thirdly how does science determine the geologic activity and evolution of planet then lastly what is the evidence that venus and mars were once more earth-like and why did they change mercury orbits so close to the sun that it is difficult to observe from earth and little was known about it until 1974 when the marinette spacecraft first flew past mercury and reveal the planet with a heavily created surface resembling a larger version of earth's moon analysis of the marinetin thin space data showed that large areas have been flooded by lava and then created spectacular new images and data arrived from the messenger spacecraft that flew by mercury three times before finding settling into an orbit around the planet in 2011. beginning a close-up investigation it lasted until it ran out of maneuvering field and crashed in 2015. an image a we can see enhanced color mosaic images from the messenger spacecraft of the portion of the planet mercury containing the glorious multiprint basin the color enhancement emphasizes variations in compositions among different parts of the surface yet an image b the origin of the spiral formation photographed by messenger is a puzzle and in c low baits crops cross craters indicating mercury cooled and shrank wrinkled its crust after many of the craters had formed the largest impact feature mercury is the glorious basin a mountain ring basin that messenger photos reveal as 1550 kilometers in diameter resembling the large ring basin moire or entirely so translated the eastern sea on earth's moon the caloris basin on mercury and mre or entirely on the moon both include concentric rings of cliffs formed by large impact though mercury looks moon-like it does have several features that earth's moon lacks mason jar photos revealed a spider of raised ring of raised ridges appearing to extend from near a medium-sized crater geologists are not sure what process could have caused the spider images from both marinette 10 and masonry review lung curve we just called low bait scalps up to three kilometers high and 500 meters long the scarves even cut from craters indicating that they formed after most of the heavy bombardment the low-bait scalps are the kind of faults that form by compression this suggests that the entire crust of mercury was compressed long ago so yeah you can go through this in your own time is the comparison between the moon and mercury mercury is quite dense and models indicate that it must have a large metallic core in fact the metallic core occupies about 75 of the radius of the planet in a sense mercury is a metal planet with a thin rock mantle and crust spectroscopic observations indicate that mercury has an extremely thin atmosphere that may be partly outgassed from the crust and partly captured from the solar wind the accumulated facts about mercury don't really help you understand the planet until you have a unifying hypothesis like a story it must make sense and bring the known facts together in a logical argument that explains how memory got to be the way it is mercury is small that fact has determined much of its history like earth's moon mercury has lost much of its internal heat and this is no longer geologically active in the first stage of its planetary history mercury differentiated to form a metallic core and a rocky mantle the presence of a magnetic field about one percent as strong of earth's further evidence of a metallic core you learn in chapter 15 that a condensation sequence could explain a high abundance of metals in mercury but detailed calculations show that mercury contains even more iron than the condensation sequence would predict drawing on large impact hypothesis for the origin on earth's moon scientists proposed that mercury suffered a major impact after differentiation that drove away much of the rocky mantle however data from messenger including images of surface hollows in many locations indicate that a substantial amount of volatiles were incorporated in a crust and subsequently vaporized abundant volatiles would not have survived a gun impact so an impact may not after all be the explanation for the size of mercury's metal core mercury is now a one plate planet much like earth's moon and lacking a significant atmosphere to erode its surface has changed little since the last larva hardened the mosaic of messenger enhanced color images section of the floor and peeking big green mountains of mercury's radar ladder impact basin the individual frames in this mosaic are about 20 kilometers wide the round the depression is called hollow seen in many locations on mercury may have been formed by sublimation of a volatile component in the surface material you might expect venus to be much like earth its diameter is about ninety percent of earth's diameter it has a similar average density and composition and it is just thirty percent closer to the sun unfortunately the surface of venus is perpetually hidden below thick clouds and only in the past few decades have planetary scientists discover that venus is a deadly hot desert world of volcanoes lava flows and impact craters laying within a deep atmosphere of hot gases no spacesuit is tough enough to allow you to visit the surface of venus in a composition temperature and density the atmosphere of venus is more hades than heaven the air is unbreathable very hot and almost a hundred times denser than earth's day so how did temporary scientists notice because us and soviet space probes descended into the atmosphere and in a few cases landed and reported back from the surface in composition the atmosphere of venus is roughly 90 carbon dioxide the rest is mostly nitrogen with some argon and sulfur dioxide and small amounts of sulfuric acid hydro chloric acid and hydrofluoric acid there is only a tiny amount of water vapor on the whole the composition is deadly unpleasant and would certainly smell bad too spectra shows that the impenetrable clouds that hide the surface are made up of droplets of sulfuric acid and microscopic crystals of sulfur the four main cloud layers and atmosphere of venus are more than 10 times higher above the surface than our earth's clouds they're completely out of surface if you could insert thermometers into the atmosphere at different levels you would find that lower atmosphere is much hotter than that of earth as indicated by the redline in a graft and something interesting so the u.s and russian landis that has landed on the surface of venus and seen pictures those landers operated a maximum of an hour they became so hot that the soldier literally these sort of circuit boards dissolved itself so the solder actually became liquid again and ran off the pcbs and that's how those landers were lost the strange atmosphere is 99 denses in earth's atmosphere so the air you breathe is a thousand times less dense than water but venus is only 10 times less than water if you could survive the unpleasant conditions you could strap wings in your arms and fly in venus atmosphere the surface temperature on venus is hot enough to melt lead and you can understand that because the thick atmosphere creates a severe greenhouse effect sunlight falcons down through the clouds and warms the surface but heat cannot escape easily because the atmosphere is opaque to infrared radiation traces are sulfur dioxide and water vapor help trap the infrared but it is the overwhelming abundance of carbon dioxide that makes the greenhouse effect on venus much more severe than on earth although the thick clouds on venus are opaque to visible light they are transparent to radio waves so astronomers have been able to map venus using radar as early as 1965 earth-based radio telescopes made low resolution maps but later both us and soviet spacecraft orbited venus and mapped its surface by radar maps made made in the early 1990s by the modular spacecraft reveal objects as small as 100 meters in diameter radar maps of venus are reproduced using arbitrary colors in some maps scientists have chosen to give venus an overall orange glow because sunlight filtering down through the clouds bathes the landscape in a perpetual sunset glow other radar maps have been colored grey the natural color of the rocks you need other maps lowlands are colored blue but there are no oceans on venus when you look carefully at colored radar maps of venus recall that its surface is a deeply dry desert by international agreement names on venus are all female with three exceptions maxwell a high mountain an alpha region and beets are richer two high volcanic peaks which were all named before the iau name convention for venus was adopted so the iau is the international astronomical union radar maps show that venus is similar to earth in one way but strangely different in other ways nearly 75 of earth's surface is covered by low lane with selling sea floors and 85 percent of venus surface discovered by the silicon lands there's no liquid water on venus however so it's lowlands are not really sea floors and the remaining highlands are not like well defined continents you see on earth whereas earth is dominated by plate tectonics something different is happening on venus the island area is named for the babylonian goddess of love is about the size of australia at its east age the mountain called maxwell montes rises to an altitude of 12 kilometers with the impact crate at le petra on its lower slopes for comparison mount everest the tallest mountain on earth is 8.8 kilometers high down the mountain ranges in the north and west the center of istantera is occupied by lakshmi plum a great pluto about four kilometers above the surrounding plains the collapse caldera's colette and saka jave suggests that a lakshmi planning is a lava plain the mountains bounding each tartera including maxwell resemble folded mountain ranges which suggests that limited horizontal motion in the crust as well as volcanism have helped form the highlands free radar maps showing different aspects of venus surface as shown in this figure the main map at top shows elevation for most planets or missing the polar areas the insect map at left shows the electrical property of surface minerals related to chemical composition and a detailed map of maxwell monitors and lakshmi planners in sit at right a scalar to show degree after rain roughness with the purple representing smooth and orange rough as usual you learn more about other worlds by comparing them with each other and with earth so notice three important ideas plus two new terms first there are two main types of volcanoes found on earth composite volcanoes are associated mostly with plate boundaries and shield volcanoes are associated with hot spots that are not related to plate boundaries volcanoes on venus and mars unlike on earth all have the shape of shield volcanoes the kind produced by hot spot volcanism rather than by plate tectonics mean thirdly some volcanoes on venus and mars are very large they have grown to great sizes because of repeated eruptions at the same place in the crust this is also evidence that neither venus or mars has been dominated by horizontal plate tectonics like earth's many features on venus testify to its volcanic history radar maps reveal shield volcanoes and long larva channels volcanic features include the coronae circular bulges up to 2 600 kilometers in diameter boarded by fractures volcanoes and lava flows corona appear to be produced by rising convection currents of molten magma that push up under the crust when the magma draws the crust sinks back but the circular fractures mark the edge of the corona volcanic features on venus in a aerospace 600 kilometer segment of bolt as well as the largest lava flow channel in the solar system it is at least six thousand eight hundred kilometers long then image b in corona about 200 kilometers in diameter is marked by faults lava flows small volcanic domes and pancake terms of solidified larva in an image c this perspective view shows a typical of those associated with corona molten lava below the surface appears to have pushed up to you causing a network of radial faults no astronauts has ever stood on venus but a few spacecraft that landed on the surface and survived the heat and pressure for a few hours some of those spacecraft analyzed nearby rocks and snapped a few photographs the surface rocks on venus are dark gray basils much like those on earth's ocean floors this is further evidence that volcanism is important on venus while you are thinking about volcanoes you can correct the common misconception the molten rock that emerges from volcanoes comes from pockets of melted rock in the upper mantle and lower crust and not from a planet's molten core in this image we can see the venera 13 land that touched down on venus in 1982 and carried a camera that swiveled from side to side to photograph the surface the orange glow is produced by the thick atmosphere wing that is corrected to produce the view as it would be under the white light you can see that the rocks are dark gray isotropic analysis suggests they are vessels so here we can see the horizon of venus is visible at the top corners of this image so over here and over here and here we can see the instrument cover ejected after landing and the edge of the spacecraft radar images show that venus is also marked by numerous craters the atmosphere protects the surface from stella meteorites that would produce craters smaller than three kilometers in diameter larger meteorites penetrate the atmosphere and have formed about 10 percent as many craters on venus as on the mare of earth's moon the number of craters show that a crust is not as ancient as the luna moray but also not as young as earth's active surface the average age of the surface of venus is estimated from crates that comes to be roughly half a billion years geologic processes are not renewing the surface of venus as rapidly as earth's surface but now heavily created terrain or large impact basins remain on venus from the heavy bombardment era so mr naval you're saying didn't accidentally take the compression of the lens cap and stayed off the ground or was that another planet i'm not sure but it could be venus impact crater howie in the foreground of this megalon radar image is 37 kilometers in diameter craters in the background are 47 cylinders and 63 kilometers in diameter those radar maps have been digitally modified to represent the view as from a spacecraft flying over the craters to tell the story of venus you must draw together all the evidence and find hypothesis to explain two things the free carbon dioxide atmosphere and the peculiar geology calculations show that venus in earth should have outgassed about the same amount of carbon dioxide but earth's oceans have dissolved most of earth's carbon dioxide and converted it to sediments such as limestone if all of earth's carbon would duck up and convert back to carbon dioxide our atmosphere would be as hot as dense as the air on venus and composed mostly of carbon dioxide like venus's atmosphere this suggests that the main difference between earth and venus is the lack of water on venus that would have removed carbon dioxide from the atmosphere there is evidence that venus had oceans when it was young but being close to the sun it was warmer and the carbon dioxide and atmosphere create the greenhouse effect that made a planet even warmer [Music] that process could have vaporized any oceans that did exist and reduce the ability of the planet to predict to purge its atmosphere of carbon dioxide as more carbon dioxide was outgassed the greenhouse effect grew and even more severe this venus was trapped in what is called a runaway greenhouse effect the intense heat and surface may have affected the geology of venus by making the crust more flexible so that it was unable to break into moving plates as on earth there are no signs of real global plate tectonics on venus but rather evidence that convicted currents below the crust are deforming the crust to create coronae and pushed up mountains such as maxwell other mountains like those around ishtar terra appear to be folded mountains caused by limited horizontal mountains in the crust driven perhaps by convection in the mantle the small number of craters on the surface of venus indicates that the entire crust have been replaced within the last half billion years or so the resurfacing may have occurred in a planet-wide overturning as the cold crust broke up and sank and lower flows created a new crust hypothesizing such drama may not be necessary however models of the climate of venus showed that an outburst of volcanism could increase the greenhouse effect and drive the surface temperature up by as much as 100 degrees celsius this could further soften the crust increase the volcanism and push the planet into a resurfacing episode this type of catastrophe may happen periodically on venus or the planet may have had a single geologically recent resurfacing event in either case unearthly venus may eventually reveal more about how our own world works now we're going to start discussing mars so mars is a medium-sized world about half the diameter of earth the surface is old cratered and marked by volcanoes but as you explore watch for evidence that water once slowly the martian a contains 95 percent carbon dioxide three percent nitrogen and two percent argon that is much like the chemical composition of the ion venus but the martian atmosphere is very thin less than one percent as dense as earth's atmosphere one thing thousands as things as venus atmosphere there is very little water in the martian atmosphere and the polar caps are composed of frozen water ice coated over by frozen carbon dioxides and dry ice as summer comes to a martian hemisphere planetary scientists observed that a carbon dioxide and a polar cap turning from solid to vapor and adding carbon dioxide to the atmosphere while winter in the opposite hemisphere is freezing carbon oxide out of the atmosphere and adding that to that polar cap liquid water cannot survive on the surface of mars because the air pressure is too low any liquid water would immediately boil away and if you step out of a spaceship on mars without your spacesuit your body heat would make your blood boil whatever water sprays on mars must be frozen in a polar caps or in the form of permafrost within the soil although the prison atmosphere of mars is very thin you will see evidence that a climate wants permitted liquid water to flow over the surface so mars must have had must must have one's hand a thicker atmosphere as a terrestrial planet it should have outgas significant amounts of carbon dioxide or general water because it was small it could not hold on to its gases the sky velocity are mars only five members per second less than half of earth's so it was easier for rapidly moving gas molecules to escape into space another factor is temperature of a planet if mars have been called the gas molecules in its atmosphere would have been traveling more slowly and would not have escaped as easily you can see this in figure 17.8 that plots the escape velocity for each planet versus the temperature of the region from which molecules will escape for earth the temperature is that of the upper atmosphere for mercury the empress that of the hard rocky surface clearly smalls cannot keep atmospheric gases easily so here we can see this so the spot describes the ability of different planets to retain atmospheric gases each red dot represents a temperature and escape velocity from the labeled planet the blue curves indicate how typical highest velocities of gas atoms and molecules labeled on the right ends of the curves depend on temperature and particle mass gases that given planet can retain correspond with curves falling below the planet's data point and jovian planets left in upper left portions of that plot have high escape velocities and can hold onto low mass molecules mars bottom center has relatively weak gravity and although it has a low temperature not only more massive molecules the moon has such a low escape velocity that all gas particles can escape it does not have a permanent atmosphere so in your own time you can go through this diagram of venus compared to mars the further problem is that mars has no ozone layer to predict its atmosphere from ultraviolet radiation so sunbathing on mars would be a fatal mistake the ultraviolet photons can break atmospheric molecules up into smaller fragments which escape more easily for example water can be broken up into hydrogen and oxygen this mass is large enough to have had a substantial atmosphere when it was young may have had water falling as rain and collecting on rivers and lakes it gradually lost much of its atmosphere and is now a cold dry world if you ever visit another world mars may be your best choice you will need a heated pressurized spacesuit but mars is much more spitable than the moon or venus it is also more interesting with whoever complex geology and science water once flowed over its surface you might even hope to find trains traces of ancient life hidden into rocks spacecraft have been visiting mars for almost 40 years two viking landers first touched down in 1976 rover's spirit and opportunity landed in 2004 carrying instruments to explore the rocky surface the phoenix robot laboratory landed in the north polar region in march the sophisticated rover laboratory curiosity landed and began its exploration of mars in 2012 and we had uh what was the latest one that landed on mars why i can't i remember the name uh yes curiosity uh but remember curiosity landed in 2012 so which is the latest one maybe just quickly look yes i saw that door found on mars but uh that could be edited photos so the latest one that was landed was perseverance in 2021 so the door found on mars so we are really skipping about it so it's usually when something like that happens each a usually internet hoax if it was true they would have been now been press releases a press conference like that you watched the press conference last week about the sagittarius a star the black hole in the middle of our own galaxy so if there was really a door discovered there would have been a similar press release cell image a rover's spirit and opportunity were directed from earth to move across the surface of mars explore features digging soil grind the surface of rocks to explore the interiors and make spectroscopic analysis image b rover spirits discovery of sulfate deposits and soil confirms other evidence that a body of salty water once covered area and evaporated leaving the sulfates behind images made by a series of orbiting probes showed that the southern hemisphere of mars is a heavily cratered highland region estimated to be at least two to three billion years old the northern hemisphere is mostly a much younger london plane with fewer craters this london plane i have been smoothed by law of flows but growing evidence suggests that it has that it was once filled with an ocean a controversial hypothesis discussed in the next section the volcanism on mars is dramatically evident in the ferris region a highland region of volcanoes and lava flows forging 10 kilometers above the surrounding surface a similar uplifted volcanic plane the elysium region is more heavily created and eroded and appears to be older than ferris oce the lack of many impact creators suggests that some volcanoes have been active within the few last few hundred million years these hemisphere maps of mars are color-coded to show elevation the northern lowlands lie about four kilometers below the southern highlands volcanoes are very high and the giant impact basin sahilas in algeria are low so note that the deaths of the canyon valles marinerists the two viking spacecraft landed the mars in 1976 far find pathfinder 19 in 1997 and river spirit plus opportunity 2004. the phoenix landed 2008 curiosity in 2012 and perseverance in 2021 oil volcanoes and deep canyons mark the surface of mars three large shield volcanoes in the ferrous region plus olympus mons stand out in this false color image olympus mons is much larger than lao the largest mountain on earth the vast size of olympus mons is evidence that the crust of mars must have remained stationary over a hot spot so the magma source and mars has not had horizontal plate tectonics the valles marina's canyon complex extends across the distance equal to the wolf of the continental united states the three ferrous volcanoes are also visible in a viking spacecraft photo the fact that velus marineris borders the fairest rise is evidence of some planetary scientists that they have a common origin all of the volcanoes on mars are shield volcanoes which you learned earlier are produced by hot spots penetrating upward for the crust and are not related to the plate tectonics olympus mons larger volcano on mars is 600 kilometers in diameter and its base rise is 22 kilometers high so the largest volcano on earth and hawaii rises 16 kilometers above its base on a sea floor one lower so heavy that it has sunk into earth's crust producing an undersea moat around its base in contrast olympus mons more than twice as high has no notes and is surrounded entirely by martian crust so evidently the crust of mars is stronger and thicker than earth so do you think olympus mons is 22 kilometers high mount everest is roughly eight kilometers high the size of olympus mons also provides clear evidence that plate tectonics has not been significant on mars on earth shield volcanoes such as those that form the iwan islands occur over rising currents of hot material in the mantle because the plate moves the heart material heats the crust in a string of locations and form a chain of volcanoes instead of a single large feature the wine islands are merely the most recent of a series of volcanic islands called the hawaiian emperor island chain which stretches nearly 5 800 kilometers across the pacific ocean floor in contrast a lack of plate motion on mars has allowed rising currents of magma to heat the crust repeatedly at the location of olympus mons and other volcanoes holding huge volcanic cones much larger than any on earth when the crust of a planet is strained it may break producing folds and rift valleys near the ferris region is a great valley valley's morineris named after marin 9 spacecraft that first photographed it this valley has a block of crust that has dropped downward along parallel faults erosion and land slides have further modified the valley into a great canyon stretching almost one-fifth of the way around the planet it is four times deeper nearly 10 times wider and over 10 times longer than the grand canyon the number of craters in the valley indicates that it is one to two billion years old placing its origins sometime before the end of most active organism in the ferris region before you can tell the story of mars you must consider a difficult issue water how much water has mars had how much has been lost how much remains the quest for warts on mars is exciting because biologists are sure that life on earth depends on water you will learn in the section that most evidently had abundant liquid water on its surface for at least as long as it took life to arose on earth these conditions under which life started on earth exist on mars at the same time they must provide a real opportunity for scientists to check their hypothesis about how life began on earth beginning in 1976 with the viking program and continuing to the present day spacecraft orbiting mars such as mars odyssey which reached mars 2001 mars expressed in 2003 and the mars reconnaissance orbited in 2006 have returned photos showing that water once flowed over the surface all of those missions expect viking are still operating at the time of the striking of july 2016. as you have learned liquid water cannot exist now on a martian surface because it will boil away in the extremely low atmospheric pressure so evidence that water once flowed on mars means that a surface conditions there must have been quite different long ago so i'm glad your chemistry tests went quite okay several types of formations hint at martian surface water outflow channels appear to have been cut by massive floods carrying as much as 10 000 times the volume of water flowing down the mississippi river such floods apparently swept away landscape features and eroded deep channels the number of craters formed on top of the outflow channel showed that they are billions of years old valley networks look like meandering riverbeds that probably formed over long periods the valley networks are also located in a heavy created southern hemisphere so they must be very old as well there are many other signs that there has been water on the martian surface some of which are geologically recently regions of collapsed terrain appear to be places where subsurface water has drained away gullies leading downhill appear to have been eroded recently judging from the lack of craters and a few gullies have been seen to appear between one martian year and the next in 2015 the mars reconnaissance orbiter made spectroscopic observations confirming present-day seasonal underground water flows these images made by the vitamin orbiters so some of the features that suggest liquid warts on mars image a outflow channels are broad and shallow and deflect around obstructions such as craters they appear to have been produced by sudden floods and then an image b valley network resembles drainage patterns and suggest water flowing over long periods crate accounts show that both formations are old but valiant networks are older than outflow channels some regions appear to have collapsed because of the withdrawal of subsurface water splash craters suggested water was present in the crust a runoff channel resembles a meandering river bed gullies appearing in steep slopes during a single martial year may indicate water flowing from melted permafrost and a central channel suggests long-term flowing water many flow features lead into northern lowlands and the smooth to render has been interpreted as an ancient ocean floor features along the edges of the lowlands are comparable to the shorelines and many planetary scientists conclude that the northern lowlands contained an ocean when mars was younger did more spawns have enough water to fleshy ethereum is three to five times more abundant relative to normal hydrogen in the martian atmosphere and then on earth suggesting that mars once had at least 20 times more water vapor than that now presumably much of that water was broken up by solar uv radiation and a normal hydrogen disproportionately lost to space like the process hypothesized to have destroyed venus's water so a question if life is heavily dependent on water then why isn't there some kind of life on the jurgen planet such as uranus and neptune i mean some kind of resilient bacteria at least and then what does he mr naval i think this was mentioned a while ago before the moon assignment the plagiarism checks you today does that mean we can no longer access it after today would and then so as far as i know the exam will also be online so we'll have online test and online exam unless something has changed but as far as i know everything is still online and then yes going back to your lives at the last chapter of this module we will have an entire lecture just on possibility of other life and yes that is possibilities being investigated so one of the area of interest is a robot that might support life so will we have to download a specific browser you can use any browser that you using it abundant morse water could survive frozen in a soil and crustal rocks instruments aboard the mars odyssey spacecraft detected water frozen in the soil over large areas of the planet if you added a polar bear change the colors and hit the craters in figure 17.14 it would look like the broken pack ice on earth's arctic ocean mars express photographs these dust cover formations in a martian equator and a shallow depth of the crater suggests that ice is still there just below the surface in image a light the broken back eyes these formations near the equator of mars suggest floating ice that broke up and drifted apart scientists proposed that the ice was covered by a protective layer of dust and volcanic ash and may still be present in an ehb radar border mars express satellite probe believe the surface to image water ice below the south polar gap the black circle is the area that could not be studied from a satellite's orbit then image c this view from the phoenix lander shows the landscape of mars north polar plain including polygonal cracks understood to result from seasonal expansion and contraction of ice on the surface then an image d in some regions of the north polar cap layers of ice plus dust with different orientations are sub is super imposed suggesting periodic changes in americans climate much more of the may isomers hidden below the gaps radar aboard the mars express orbiter was able to penetrate 3.7 kilometers under the surface and map ice deposits in the crust of the planet's solar polar region a southbound region there is enough water today at least 90 cleared to cover the entire planet to a depth of 11 meters the phoenix probe landed in 2008 years more small finding water ice mixed with the soil not only a sperma frost but also small chunks of beer ice indicating there once was standing water that froze in place river spirit and opportunity area suspected of once having had water on their surfaces as of july 2016 opportunity was still roving and communicating with earth near 12 years off that landed so far as i know opportunity stopped working rambo 2019-2020 both rovers have found evidence of past water including small spherical concentrations of the mineral hematite dubbed blueberries that require bun and water to form in other rocks opportunity found layers of sediments with ripple marks and cross layers showing they were deposited in moving water chemical analysis of the rocks at both opportunity and spirit sites detected sulfates much like epsom salts plus bromocytes and chlorides on earth these compounds are left behind when bodies of water such as desert lakes dry up in his first year at work curiosity rover discovered rounded rocks of the sword produced by running streams in image a rover opportunity photographed hematite concentrations and blueberries wavered from rock the round mark is a spot cleaned by the rubber the spheres appeared to have grown as minerals collected around small crystals in the presence of water similar concentrations are found on earth in an image be the layers of this rock were deposited as sand and silt in rapidly flowing water from the way the layers curve and cross each other geologists can estimate that the water was at least 10 centimeters deep a few blueberries are also visible in this image mars has water but that is hidden when humans reach mars they will not need to dig far to find water in a form of ice they can use solar power to break the water into hydrogen and oxygen hydrogen as fuel and oxygen is the breath of life so the water on mars may prove to be buried treasure even more exciting is the knowledge that mars definitely once had bodies of liquid water on its surface it is a desert world now but someday an astronaut might scramble down an ancient martian streambed turn over a rock and find a fossil it is even possible that life started on mars and has managed to persist as the planet gradually became less hospitable for example life may have hung on by retreating to limited warm and wet oasis underground you will learn in a final chapter about possible evidence of ancient life in one of the martian neutralized dead moss either have plate tectonics where the reward to go these fundamental questions challenge you to a single evident hypothesis for mars and tell the story of its evolution the fourth stage history of mars is a case of a risk development the planet began by differentiating into a crust mantle and core studies of expectation reveal that it has dense coal the mars global survey spacecraft detected no planet-wide magnetic field but i did find regions of the crust with fields a bit over one percent as strong as earth's apparently the young mars had a molten iron core and generate the magnetic fields which became frozen into parts of the crust the core must have cooled quickly and shut off the dynamo effect that was produced in the planet-wide field the magnetic regions of the crust remained behind large fossils the crust of mars is now quite thick as shown by the mass of olympus mons but it was probably banana past cratering may have broken or at least weakened the crust triggering lava flows that flooded some basins most of the northern hemisphere may have been a huge impact basin that was later filled with water cratering a martian ocean that has since vanished mental conviction may have pushed up the ferrous and elysian volcanic regions and broken the crust to form vellus marianas but moving crustal plates never dominate mars there are no fallen mountain ranges on laws no sign of blade boundaries the large size of volcanoes on the planet is evidence that a crust does not move plenty scientists therefore conclude that as mars interior cooled its crust grew thick and immobile at some point in the history of mars water was abundant enough to flow over the surface in great floods and may have fallen oceans but the age of liquid water must have ended more than 3 billion years ago the climate of mars has changed as atmospheric gases and water were lost to space and as water was frozen into the soil as permafrost for mars the fourth stage of planetary development has been one of moderate activity and slow decline volcanoes may still occasionally erupt but this medium-sized planet has lost much of its internal heat and most volcanism occurred long ago the atmosphere is thin and the surface is a full fittingly dry cold desert venus and more share at least one characteristic they have evolved since they formed and are now quite different than they were when the solar system was young moreover as you have learned planetary scientists have evidence that the surface conditions on venus earth and mars were much more similar long ago than there are now so notice four import points so firstly the difference between venus and earth is not the amount of co2 they have outcast but amount i have removed from the atmospheres being warmer consequently having less liquid water on its surface sealed venous fate as a runaway greenhouse venus is highly volcanic with a crust made up of lava flows that have covered over any older crust the entire planet have been resurfaced with last half billion years thirdly mars is significantly smaller than earth with gravity too weak to prevent much of its atmosphere from leaking away evidence shows that mars once had liquid water on its surface but much of its water has been lost in space the low atmospheric pressure means that the only remaining water is frozen in the swell and lastly because mars is small its interior cooled relatively quickly and volcanism has died down lack of volcanism means the escaping atmosphere is not replenished the planet's crust was thinner when a planet was young but has grown thick and never broke into moving plates as did earth's crust and then mars has moons so unlike mercury of venus mars has moons the small and irregular and shaped phobos is 28 by 23 by 20 kilometers and deimos 16 by 12 by 10 kilometers are probably captured asteroids photographs reveal unique set of narrow parallel grooves phobos averaging 150 meters wide and 25 meters deep the grooves run from sticking the largest crater to an oddly featureless region on the opposite side of the satellite one few suggests that the grooves are deep fractures caused by impact that formed stigma so something interesting about these two moons of mars is their names what can you tell me about their names so what can tell them about the names so the two moons were named after the mythical attendance of the god of war phobos was the god of fear and demons was the god of dread and they off i'm not mistaking from roman mythology because i think if comparing roman mythology with greek mythology uh in greek mythology it is use and in roman mythology it is mars but both are the same thing if i'm correct so yes there are a naming convention to it so you would see most of the planetary bodies are named after roman mythology and greek mythology demos not only has no grooves but it also looks smoother because of a thicker layer of dust on its surface the material partially falls craters and covers minus surface irregularities it seems likely that demos experienced many collisions in its past so its fractures may be even below the debris oh yes that's what made them secure correct samaras equivalent to the greek areas same goes for jupiter and zeus neptune and poseidon ah thank you so much that's where it came so i know there was something to it so debris on the surface of the moons race interesting question how can a weak gravity of small bodies hold any fragments from meteorite impacts the escape velocity and phobos is only about 11 meters per second an athletic astronaut who can jump 2 meters high on earth could jump 3.4 kilometers on photos most of the fragments from the impact should escape but the slowest particles could fall back to the weak gravity and accumulate on the surface that cushioning the layer in turn could help trap more debris because demos are smaller than phobos its escape velocity is smaller so it seems surprising that it has more debris on its surface this may be related to phobos orbit close to mars the martian gravity is almost strong enough to pull those material off focal surface so phobos may be able to retain less of its greater impact debris so comment so pluto says even though it is not considered one of the planets anymore so that ladies and gentlemen was the lecturer on the terrestrial planets do you guys have any questions so i have only read the first percy jackson book why are you not a fan so it's safe to say that earth is at a kind of equilibrium as compared to other terrestrial planets yes you can make that assumption do they have any specific way of naming the moons and planets as in characters or just are so they are so conventional general moons are named news and planets are named after greek and roman mythology except neptune but we will discuss that in that chapter i haven't played therogenesis now i haven't played it so off topic what time would be leaving campus so i will let you guys know about those details i think someone has raised their hands or not so unfortunately i'm not available on campus tomorrow i have my own research to work on but we can set up a later date and time this week that can be on campus again if you need me on campus so yes mr melville you are giving away one of my favorite slides on our about uranus but we will discuss that as well so if you guys have no further questions you are more than welcome to log off i will remain active for another few minutes so so in tomorrow night's lecture we will be discussing the four jovian worlds jupiter saturn uranus and nifty so if you have no further questions then you are more than welcome to log off and i will see you all tomorrow evening i will remain active for another minute or two so a question what is this test be in a similar format to the quiz expect with more difficult questions and different type of questions so yes it will be the same form as the quizzes worth 90 multiple choice questions and a few longer questions and you will write it on click up it's a pleasure so jupiter's moons are named off these lovers that is also another slide i'm going to show you guys so how do they detect if google was used so we have software that can detect it through click up so it's up to lecturer if they want to use it or not and in my case i'm going to use it next so if you guys have no further questions then i'm also going to log off so have a wonderful evening guys and i will see you all tomorrow you