 greetings and welcome to the introduction to astronomy. In this video we are going to look at the moon landings and more specifically talk a little bit about the idea or the idea that the moon landings were a hoax. So that is what some people believe and as you may expect being an astronomer it is not something that I believe but I do think it is important to go through and look at some of their arguments and some of the evidence to show that we really did land on the moon six times back in the nineteen sixties and nineteen seventies. So as we go ahead and get started here first of all as I've mentioned we had six missions that landed on the moon those were the Apollo missions using the Saturn five rocket scene launching here and in a rocket like this the vast majority of this is all fuel so that is the fuel that is needed to lift something out of the Earth's gravitational well and get it into space and in this case on to the moon. Now the Apollo missions there were six of them that were successful and that landed on the moon and they are shown here the landing sites at least for Apollo 11 12, 14, 15, 16 and 17. They landed at various places between July of 1969 and December of 1972 and they explored those six portions of the moon there were 18 astronauts three permission 12 of them would have landed on the moon and walked on the surface the other six would have been the commander command module pilots who stayed in orbit around the moon so there were a number of 12 astronauts who walked on the surface of the moon over these three and a half years. Now even today having seen this and having some of this we know that there are still some doubts by some people as to whether these landings actually occurred. So we have some images here taken showing the astronauts the lunar lander itself the flag over here and then of course some instruments but some people do still doubt this and we want to look at some of the evidence that says that yes we really did land on the moon so what are some of the some of the direct evidence well first of all direct observations of the astronauts we have a number of astronauts who've been to the moon and they have they have their direct experience oh as long as we believe them we know that we landed on the moon we also have moon rocks that have been returned to earth so an example here is one of the moon rocks that is shown and has been been studied we've returned many hundreds of pounds of moon rocks to be studied here on earth and it is one of the few objects in the solar system that we actually have samples of to be able to study directly. Now of course this could is this to convince someone of this if someone believes this is a conspiracy or hoax how does the average person know that this is a moon rock and not something else not just an ordinary earth rock or different type of earth rock so that is something that requires specific study and does require accepting what NASA tells us about them we can also see the landing sites from things like the lunar reconnaissance orbiter that is now in orbit around the moon and here we can see one of the Apollo landing sites the lunar module right there some of the cameras some of the different equipment that was left behind is still visible today and you can also in some cases see the tracks that the astronauts may have taken so as they traveled across the lunar surface we would see the paths where they churned up the lunar soil and we can see that as well now could this be faked and this is what people will argue I mean this is not going to convince anybody because if you do not believe that NASA took people to the moon then you're unlikely to believe their observations from their orbiting spacecraft orbiting the moon or even if they truly have that so could this all be faked so let's look at some of the evidence that we're going to see because things like this if you don't believe NASA then and it's all a hoax then things like these are all going to be not going to convince anybody who believes that this is a conspiracy or a hoax so let's look at some of the evidence for this so what do some of the people who claim this is a hoax say well one is why are there no stars in the sky it's a dark we should be able to see stars here because the moon has no atmosphere it's not illuminated during the day so unlike earth where the sky is brightened because of the atmosphere on the moon it is dark and you should be able to see the stars and were you on the moon and looked up you would be able to see stars there however they would not be recorded in the camera images and that's just because of the contrast you would have very faint stars in the sky as compared to a very relatively bright lunar surface so it's like trying to get images that have something very bright so a bright beach image or a bright snow image and then trying to get detail on something dark if you want to get the stars in the image you would have to vastly overexpose the lunar surface if you take an image like this one where you're able to see the lunar surface then you're not going to be able to see the stars and there are some images such as this one here where we do see the stars this was taken by an ultraviolet telescope on the moon set up by one of the Apollo missions and we can see the earth there and we can see a number of stars and if we calculate what stars these were what their positions are it is completely consistent with them being taken from the surface of the moon and showing all of this so we do have some images it's just you can't get all of them together and as you notice here the earth itself is pretty well overexposed in order to pick up some of these fainter stars so that is one example another is the flag the flag on the moon looks like it's waving so why would the flag be waving in the lack of atmosphere on the moon well it could have been moving there's no reason it wouldn't have moved as they were setting it up but once it stayed in one position then it would remain in that position because there are no other forces to act upon it it did not extend completely the rod up here which holds it did not extend completely which is why it will appear a little bit wrinkled but we can also look if we look at our next image here where we see this how can we tell that this is actually consistent well we have a couple different images and these are two different images taken and then put together and we can see the astronaut is in two different images different positions however the flag is exactly the same in both cases were the flag moving we would not have exactly the same ripples in these two different images and that's showing that the flag has not changed its positioning between the time these two images were taken so the fact that the flag is appears to be rippled is not that it is actually moving it is just a matter of how the retaining rod holding it failed to extend and giving it sort of a more realistic type view but it would change as any flag here if you took two pictures of a flag on the earth they would never be exactly the same now as we continue to look how about the prop numbers on the moon rocks sometimes that is claimed here and what we're going to look at is one specific rock here and that is this one and if we zoom in on that one a picture another picture taken of it appears to have a prop number a prop letter the letter c on it and we go to the next image here that's that same rock that we looked at in the previous image that's the one over here and we see it again we see the letter c apparently on it and what is that is that a prop number that it was numbered as to its positioning or something as to where it should have been or what we believe is more likely it since it is not present on the original image is that it is just probably a piece of hair or something that got caught in the scanning and appeared then appears so it is not an actual letter c written on the rock and because if that were the case we would have seen it in the previous image as well and in the previous image although not zoomed in as well here although you can pull up this image you will not see any kind of sign of that and you should see that a sign of that a letter towards this side of the rock and that is completely not visible in the original image so not any prop numbers there on the rocks next where is the camera where is the camera in an image like this here we can see the image of the astronaut and there in the four there in the reflection is the astronaut taking the image and he's not holding up a camera well as you might imagine in a bulky spacesuit like this the astronaut is not going to be able to hold the camera and they needed their arms free for their emissions so the cameras were actually embedded right into the spacesuit so the astronaut is taking the image that's correct but his hand is on his chest which is where the camera was embedded and that was what is allowed to take the image of this so where is the camera well it's actually been embedded into the spacesuit so that the astronauts did not have to carry them around and then finally how about objects being illuminated one of the other thoughts is that on the on the moon there is the sun is illuminating everything so you have only the sun illuminating so everything opposite the sun should be completely in shadow so why is part of the lunar rover why is half of the astronaut or any other object that we see here still illuminated now you can see that there are definitely shadows being cast on this side of the astronaut it's much brighter with the sun coming in from this direction and this side is much fainter now what they say would be true if the sun were the only source of illumination however there are other sources of illumination as well the earth being one of them so where is the earth in the sky sunlight strikes the earth and then bounces to the moon we know that so the earth would be giving some illumination not near as much as the sun but just as here on the on the um earth you can go out on a full moon and see things relatively well by the light of the full moon you get some illumination from the moon you do get some illumination from the earth as well now that would also be much brighter because the earth reflects more light than the moon does and it is also larger so it has a larger surface area the moon appears larger uh the sorry the earth appears larger in the sky when you're on the moon then the moon does here on the earth you can also get reflection from the ground so just as things can be illuminated from the ground on the earth when you have something very bright and reflective sand or snow you can do the same thing here so the ground being illuminated by this by the sun where does that light go well some of it can reflect off the lunar lander off the astronaut off any of the instruments there to be able to give them some light not and they were not and that's why they are not completely dark so those were a few of the pieces of evidence and some of the photographic evidence that i wanted to discuss obviously i can't discuss everything in the time i have here but i did want to mention a few other things before i finish up and some of the other thoughts that i wanted to look at is how about the reflectors on the moon the astronauts place some instruments there which can be detected from earth so we can shine lasers to them bounce them off this and would be able to detect them here on earth so we know that the astronauts did place these instruments there radio transmissions are another big one how do we have radio transmissions well what does this mean if we think about this this is back in the late 1960s early 1970s and the radio transmissions were coming from the moon now of course everyone's going to say that nasa is just faking that but that would have involved other countries being involved in the conspiracy as well including the soviet union now the soviet union and the united states were of course in the middle of a cold war at the time and would the soviet union would have been easily able to tell if these signals were coming from orbit or were coming from satellites you could very easily triangulate the location and they would have known if these were not coming from the moon so it's hard to believe that at that point in time specifically that the soviet union would have let the united states get away with faking the moon landings um why is there no communications delay well there actually is if you go to the original uh tapes there should be about a two second delay because of the time it takes a signal to get to the moon and back radio signals travel at the speed of light so it would take a couple seconds so if uh the mission control were to ask a question you might hear a couple of second delay before you get a response in many cases this would be edited out when these are shown just because it would allow us things to move a little quicker when you can take off that couple seconds every single time that adds up to a significant amount of time and allows a better flow but the original tapes do show a delay uh there's also arguments that the astronauts could not have made it because of radiation the van allen radiation belts that the astronauts would have passed through would be very intense radiation and could be very damaging however the shielding of the astronauts uh and their spacecraft would be sufficient to be able to cover them for the time they traveled through these belts um in the longest case it probably took them an hour or so to get through one of the belts and that the shielding of the spacecraft would be sufficient to have kept their radiation doses to a typical ordinary level here on earth over that short of time yes you don't want to just live in the radiation belts that would eventually would be damaging but the time it took them to travel through them that would not have been significant and then finally the last thing I wanted to look at was how about gravity on the moon so we know that the moon has less massive than the earth and therefore has less gravity so here we have a clip from the Apollo 15 mission showing an astronaut with a hammer and a feather in his right hand is the hammer in his left hand is the feather so he's going to drop these two here in just a little bit and we will watch them fall and I want you to note two things first of all you note that they fall at the same rate now a hammer and a feather dropped here on earth will not fall at the same rate that will only happen in a vacuum where there is no air resistance to hold up the hammer and you'll also note that they fall at this at a much slower rate than they would here on earth so if you can imagine dropping a hammer here on earth it would fall very quickly and here it kind of falls relatively slow that's because of the lower gravity about one sixth of the earth's gravity on the moon so we notice that those two things happen and those would be difficult to reproduce in the in the in a studio here on earth how could we get a complete vacuum in order for that feather to fall just as fast as a hammer and we'd also have to simulate that things were falling at a much slower rate so two very difficult things to do especially when this was done live on tv so just a few things to think about in terms of this so let's go ahead and finish up as we do with our summary and what we looked at and I mentioned between 1969 and 1972 we had 12 astronauts who walked on the moon although to this day there are some who still believe that this never happened and to really to doubt these requires a complete disbelief in everything nasa and not just nasa but other space agencies has done so we have demonstrations not only from nasa but from other countries who have been able to find with their spacecraft evidence of the lunar landings the difficulty is of course we cannot see them from earth so when we look at these we can't see the lunar lander with even the most powerful telescope here on earth that's just not possible the resolution is insufficient to see something that small but spacecraft from nasa and from other countries have been able to do these from lunar orbit so as long as you accept what nasa has done in being able to put astronauts into orbit then it is perfectly reasonable and based on the evidence that yes we did send astronauts to the moon back about 50 years ago so that concludes this lecture on the moon landings we'll be back again next time for another topic in astronomy so until then have a great day everyone and i will see you in class