Eclipses (1950)

[Music] the mysteries of nature are as infinite as they are fascinating thousands of books have been written in an effort to explain these Mysteries and the man who can best explain them is of course our friend with the encyclopedic Mind Mr John Kieran right now Mr Kieran is in his library with Paul Milford his nextdoor neighbor let's listen John we've been looking down at the ground and under the water pretty consistently through that magic caleidoscope of yours how about looking somewhere else fair enough how' you like to see an eclipse well I think I would I don't recall having seen any lately well not surprising you don't see eclipses every day they are certainly one of the most magnificent spectacles that the human eye can behold by the way you know why we have eclipses oh sure it's uh well uh uh uh oh you don't have to say another word you know Savages used to think that an eclipse was caused by dragons trying to swallow the sun of the Moon but we know better now and we can show how it occurs you are looking at a moving picture of a total eclipse of the sun it's a long time between total eclipses of the Sun in any given area and they pass very quickly when they do occur there are also eclipses in the moon they last a little longer but they are even rarer sites on Earth than eclipses of the sun now we propose to show not in a deep scientific fashion but in a simple way how these eclipses occur that Spike knob in the center there can represent the Sun for us and the spinning ball going around it the Earth we know the Earth does go around the Sun once a year now we also have a smaller ball going around the earth that can represent the moon we know the moon does go around the earth about uh once in four weeks or so these models are not in scale for size or distance but just for our convenience this is the Silvery light of the Moon Over which we waack so sentimental but to tell you the truth it's a borrowed light it shines by reflected Glory from the Sun now we know that we have a full moon a half moon a new moon and all that a full moon is when it is in this position on the far side of the earth from the sun and we have a full Reflection from the rounded surface of the moon's body now the Earth being a solid body casts a shadow and when the moon goes behind the Earth in this fashion you would think that it would fall into the shadow of the earth well it occasionally does just like that then the Moon is what we call Eclipse now here's another illustration of it here the light of the sun is coming from the left where the arrows point the dotted line is the path of the Moon the Earth is in the center throwing that heavy dark shadow through which the Moon is now moving the shadow of the earth there where the moon is going through is approximately 5,700 mil across so it does take the moon a little time to go through it now this is a moving picture of an actual eclipse of the Moon a total eclipse a central Eclipse it seems that the shadow of the earth is creeping across the face of the Moon of course it really doesn't happen that way it's the Moon that sails into the shadow of the earth and it sails out again too notice that the shadow of the earth is curved it's a circle and that's another way of proving of course that the Earth is round sometimes the moon doesn't go all the way into the shadow of the earth only partially then we have a partial eclipse of the moon something like this incidentally a total eclipse of the moon can take about an hour and 40 minutes at a maximum but we speed things up here for our own convenience by time-lapse photography now this is another graphic illustration of the path of the Earth around the sun the sun being in the center and the path of the Moon around the earth we also show the shadow of the earth into to which the moon occasionally goes to be eclipsed now if the these things were all on a level as we might say then every time the moon went behind the Earth it would be in that shadow and we would have an eclipse at every full moon but we don't the reason for that can be shown if we put them in this fashion and you will see that the orbit of the moon around the earth is not in the same plane as that of the Earth around the Sun it's tipped at that angle which is roughly a little more than 5° 5° 8 minutes say so that most of the time on its trips around the earth the Moon is either above or below a straight line through the Earth and the Sun it's only when the three bodies are in a straight line that an eclipse can occur that the Earth can throw a shadow that the moon will enter or that the moon can be interposed between the Earth and the Sun now here the moon has gone into the shadow of the earth and is in eclipse now we remember that the moon also goes between the Earth and the Sun and when it gets into a straight line then the shadow of the Moon falls on the earth in this fashion there it's creeping up and now it's well on the surface of the Earth here we have a Graphic illustration of it the sun's Rays coming up from the bottom the cone uh Shadow because the sun is so much larger that the shadow of the moon is a cone and it writes a narrow line of that kind on the surface of the Earth of course the astronomers figure out in advance exactly where that narrow band of totality as they call it will fall on the face of the Earth and then they pick a good spot on Solid Ground because a lot of that path lies across water and go to that place to make their observations now here's another illustration we let the light coming from the right be the Sun the ball hanging in the middle be the moon when the light shines you see the shadow falls on the screen which can be the surface of the Earth the shadow is darkest at the center then it fades out to a partial Shadow and beyond that there is no Shadow or Eclipse well it's the same way uh with this path of the uh total eclipse that's dark and uh complete Shadow beyond that for a couple of thousand miles we have a partial eclipse where only part of the light is cut off and beyond that there is no eclipse at all people who live there are able to see the sun clearly and the Moon is not in the way now there was an eclipse of the sun on June 19th 1936 in Japan that is it was visible from Japan this is merely a repeti ition to show how on most of its trips around the earth the Moon is either above or below the point of straight lines and no eclipses occur and this is a an illustration of the sun on the right the moon in the center and the path of total and partial eclipse thrown on the surface of the Earth the eclipse in Japan uh caused a great many scientists to gather there of course with all their instruments to uh take measurements of the relative positions of the Sun the Moon and the Earth and make observations on the planet Mercury which is very close to the Sun and best view during a time of total eclipse and they measure the heat the radiation thrown off by the Sun and they take uh views of stars that they can only see at that time because they also are close to the Sun some of the natives don't take any stock in that they think it's a dragon swallowing the moon and they beat on Dish pans to scare off the dragon and and Save the Sun and when the eclipse is over of course they take credit for driving away the dragon and saving the Sun for us of course the astronomers uh don't take much stock in that theory they have as I say their own purposes and scientific measurements to take watch this approach to the moment of totality this we are now getting to the stage of what's called a the diamond ring uh appearance uh let that uh glow up at the top represent the diamond and you'll see why this is called a diamond ring uh stage of a total eclipse we can also see other phenomena at uh such times where the arrow is pointing that is called a solar prominence it's a it's a huge explosion of of incandescent gases now that arrow on the right points to a globe representing the the Earth 8,000 mi in diameter so you can see the the vastness of that explosion of that solar prominence where there was a a wonderful total eclipse of the sun visible from Minnesota to Connecticut on January 24th 1925 I saw it certainly was a magnificent or inspiring spectacle it lasted only a couple of minutes the total possible length of a uh eclipse of the sun is 7 minutes and a fraction but the astronomers will settle any time for a 3 or four minute Totally Clips without interference by the clouds as I say it doesn't last very long the next one visible in the United States will be from Florida to North Carolina March 7th 1970 maybe we can meet there but it's very quickly over you'll see that the uh sunlight is now streaming around the edge of the body of the Moon which is moving away in fact it looks as though day is breaking the rooster salutes it with a crow and really although it's a magnificent spectacle to all of us it is a relief to have the sunlight by which we all live and breathe come streaming back to us on Earth again [Music] [Applause] [Music] [Applause]