all right is the final layer of the sun's atmosphere we talk about the solar wind you know you look in a textbook they'll talk about three atmospheric layers the photosphere the chromosphere and the corona you'll see I thought there was only three but many times the solar wind is referred to as the fourth atmospheric layer even though it doesn't really have a well-defined height or really anything else for that matter rather it's the effects that you feel farther away from the Sun due to the basically a vacuum of interstellar space we feel the flow of particles and radiation away from the Sun they're very long periods of time even as far away as Earth because again of the lack of hindrance to the flow of anything away from the Sun so we'll call these effects the solar wind so there's a fancy word if the solar wind is a plasma flow of ions yeah both protons and electrons and magnetic fields you know it's all so hot that it has stripped many of its electrons many of its atoms of electrons and it's hurling those free electrons its hurling those free ions the ones that have been stripped of their electrons at us and of course on their way to earth they can recombine along the way or they can actually remain individualised as well meaning both electrons and positively charged ions and anytime you have a flow charged particles that are dynamically moving all the time and therefore they're accelerating they're changing their direction all the time that's all you need to generate a magnetic field so it's pretty hard to have charged particles and not have magnetic fields and especially if they're turbulent and moving all the time then they're all just intertwined is what we call this high temperature a soup of electrons and ions and magnetic fields a plasma so someday you can take a course in plasma physics which is talking about well just these high-energy ionic soups of very charged particles who's causing the solar wind well it's really the last layer of the Sun it's very high temperature one to two million kelvins touching the the coldness of space interstellar space is you know maybe three kelvins you know it's almost absolute zero right it's so cold and what happens on earth when we have a huge temperature in in one area and a low temperature in the other areas on earth there's a huge flow of particles or wind literally from high pressure to low pressure and that's exactly what you have in the sun's case you got high pressure at the Crick at the corona with all this stuff trying to leave the very very hot Sun and clearly it can easily escape into the coldness of space doing its best job to try to bring it to equilibrium and never well there's not enough source of energy and the Sun to heat up the entire universe so this flow is very natural and very um appropriate it just makes a lot of sense to us that you would flow from high pressure to low pressure so yeah all these particles are escaping the Sun and of course they have to be moving fast enough to escape the Sun's gravitational pole so that requires a very large velocity and these large velocity is again are caused by the incredibly high temperatures in the corona yeah the coldest of space you know in between the stars is like three kelvins it's a little bit warmer in interplanetary space in our solar system but still the temperature just outside the Sun is awfully cold maybe not quite three kelvins but it's awfully cold now what kind of things do we see in our everyday lives that you know exhibit the solar wind and probably the most common example that we rely on those comments comets are big huge dirty snowballs and there's plenty of them below beyond the orbit of Pluto in what is called the the Oort cloud and some of these snowballs get perturbed by the planets that are in that area Neptune and Pluto and other smaller dwarf planets and they can tug on when these snowballs and send it off to the Sun puts it into a fairly elliptical orbit and as these snowballs approach the Sun the temperature of course starts to heat them up and the ice ball itself will sublimate a fancy way of saying evaporate directly from a solid into a gas kinda like dry ice does you know when you put in a bucket in a haunted house on earth yeah things we could do a Halloween that you see this vapor don't you kind of emanate out from the bucket well that's that's a good example of sublimation so when a comet an ice ball comes near the Sun and begins to warm it to evaporates but directly into a gas and leaves behind this trail of debris this tail or trail of debris is the comet's tail that we often see in photographs of comets that are photographed from I'll show you a photograph in just a second but we'll also find out that these tales are always pushed away from the Sun so when a comet is orbiting toward the Sun of course that's flowing in the opposite direction from its tails tails left behind but after the comet rounds the Sun and starts to lead the Sun in terms of its orbit band bizarrely enough it travels in the same direction as its tail is pointing so when you take a photograph of a comet and you see a tail to it you'd automatically think oh it's traveling in the direction opposite the tail but that's not always the case sometimes comets are flying in the same direction has their tails it just depends on where in the orbit that they are so this you know crude cartoon is showing some things that occur because of the solar wind the Suns in the center of this diagram wind is being pushed equally in all directions and the dirty-ice ball the comet that's coming in here will of course project the tail opposite the direction of the solar wind the wind is what's pushing the hair back if you will the comet with locks the earth itself and its orbit around the Sun has a magnetic field that is also being distorted the side which is facing toward the Sun is smashed if you will and the side facing away from the Sun is elongated are strewn outwards more yeah our geomagnetic tail our Earth's magnetic field lines the call smashed in the direction toward the Sun because of the solar wind and they're elongated almost teardrop shaped in the opposite direction well let's show you some images there is a comet as seen in 1976 this is called comet West not because it was flying westward but because mr. West discovered they named comments after the discoverers and what you notice here is that the comet has details it has an ion tail which is in blue that tells us the direction of the magnetic fields in our planetary system and the white tail down here is the dust tail and that's just due to the solar wind pushing it in that direction so if you see that a better spray in this direction to me as well which means the Sun is often well mostly the left were erection but maybe a little bit higher as well pushing that tail sort of been both the backwards and downwards directions and clearly the magnetic field lines don't always line up with the direction of the solar wind which is why you have two different tails and they're sort of splayed or showing a spacing between them so not uncommon when you photographed like comments especially when they're near to the Sun and start to make the around in their orbit we can see these and divergence of these two tails pretty easily now over here on the right this is from your current text you see the Sun as photographed with a certain filter on it and that's just a bizarre image of the Sun isn't it looks like there's this Canyon or sort of this crevice or crack in the Sun's corona but these are called coronal holes these dark areas and it's in those areas where most of your ions and charged particles escape easily so we say the solar wind which is just that I see a soup of charged particles and magnetic field lines are escaping through these cracks in the corona of the holes and an x-ray wavelengths you know what does x-ray photograph incredibly hot temperatures so this is the million to two million Kelvin layer of the Sun and what's happening when you don't see the crevice are the canyons is that the Sun is actually withholding our keeping in most of those parks charged particles from leaving and we'll talk about how that happens you know what is the mechanism by which the Sun can retain some of the particles but not all of them but in areas where there is holes in the corona we'll keep it that keep it that definition for a second that's what those particles escape most easily down here now sure you can see that but that just shows you the sun's magnetic field lines and how they are sort of distorted and destroyed its my a window in the way let me see if I get there we go then these field lines will trace out the magnetic field lines let me say that again the charged particles will trace out the magnetic field lines causing provenances and the cases where these uh promises are broken or snapped then you get solar flares are mass ejections and down here we you see so that this gap in between these two loops that's just where these coronal hole exists and it's easier for particles to escape from that direction yeah so it's not evenly distributed the solar wind is it's emanating away from the Sun although once it starts to fill up all of interstellar space our interplanetary space it pretty much you know does a good job of moving in all directions possible alright get in that video right here [Music]