 Greetings and welcome to the Introduction to Astronomy. In this video, we are going to talk about solar activity and space weather. So we're going to look at some of the signs of solar activity. Sunspots and the solar cycle are one of them, but there's a lot more to it than that. And then we want to see what we call space weather. And space weather is sort of weather out in space, which is all caused by the sun. So various different effects that we see coming here on Earth that are caused by solar activity. So let's get started with some of the different types of solar activity that we see. And first of all, we see the sunspots that we've looked at first. Solar sunspots here are, of course, the darker areas on the surface of the sun. But that is a part of solar activity and maybe the most visible sign of it. But we do see lots of other signs. And we can look at some of those, such as the plages, which are visible here. And we can see the brighter and denser regions. So brighter regions around here are also parts of the signs of solar activity. And in a way, we can see how they are associated with the very dark areas of sunspots. But it's not just the sunspot area itself, it's actually a whole region that is active. So it's not just that small part of it, not just the sunspots that we see. It is actually a lot more to it than that. Now some of the other areas that we can see would be things like solar prominences. So prominences on the sun are where loops of plasma being lifted off the surface. And we can see an example of that here, where material is being lifted up off the surface in kind of a little arc. Now those are associated with sunspots as well. And you can kind of imagine the magnetic field that is down here lifting up off the surface and then pushing that material up into the solar atmosphere. Now when it does that, it really does not throw the material off the sun. It comes up and then it will essentially rain back down onto the sun. So it will fall back down to the surface of the sun, never leaving the sun itself. But we can have more intense regions of this, which we call the solar flares. So a prominence may take days or even a week to slowly lift that material off the surface of the sun. In a very short time frame, in a matter of minutes, a solar flare can do the same thing. So when a solar flare occurs, we get material being ejected rapidly off the surface of the sun. And a very rapid ejection actually is fast enough to expel that from the surface. So this material actually can escape from the sun, meaning it travels out into the solar system. So there are materials, there are solar flares and very intense flares that can really get material off the surface of the sun and get that material to the earth. Now we have that in the solar wind which slowly moves material out. This is a much more intense concentration of material and therefore will give us much more in terms of things like an aurora or in terms of interfering with the atmospheres here on earth. So one other type that we get is what we call a coronal mass ejection, which is when you have these large flares and the material in the corona gets ejected at high speed, so it's even higher concentrations of particles. Now as they stream out, most of them stream out harmlessly into space and don't affect anything. However, some of them could stream towards the earth. So we want to look at a little bit as to how these storms can affect the earth. And we see here that the solar storms, can they affect the earth? Well yes, we do have solar flares, coronal holes and coronal mass ejections can have an impact on the earth and in fact the last major coronal mass ejection that really struck directly on the earth was back in 1859. So the coronal mass ejection or CME actually struck the earth then and overloaded the earth's magnetic field. So essentially when you have the earth's magnetic field which protects us from this kind of thing. So as the earth's magnetic field here shields us, but when you have a very intense burst from say the sun over here and you have an intense burst of particles coming towards the earth, they can then deform the earth's magnetic field. And that means that instead of the particles traveling way up around to the north pole to strike the earth's atmosphere, they can deform the field and they can actually hit at much lower latitudes. And that means that during this time back in 1859 the aurora were visible in Hawaii. So in place you normally don't see aurora areas close to the equator, but were actually visible there during this coronal mass ejection. And in fact the intense activity also caused sparks from the telegraph equipment. So generating currents within the telegraph wires and caused sparking with there and small fires to occur because of interference with that kind of material. Now what would happen today could be much more damaging if a major coronal mass ejection were to hit. Back in 1859 there was not a lot of electronic equipment. The state of the art would have been the telegraph equipment. So things like satellites now up in space would be even more exposed because as the earth's magnetic field is deformed they are no longer protected and they would get damaged and if they are not hardened against electrical interference like this their internal electronics could get completely fried. So it could cause major damage to our communication system. And you can actually if you want to look into this little more and see what's going on with space weather right now you can go to the Space Weather Prediction Center at the website given here, the NASA NOAA website given here. Now finally let's look a little bit about how these can possibly affect the earth's climate here. Is there a connection between the solar activity and the climate here on the earth? What could be the possible connection? Now we know the Maunder Minimum which occurred in the late 1600s which occurred here led to a time of unusually cool weather on the earth. So much less heat because of this minimum and that's there was less solar activity going on and less heat energy being generated by the sun. So what we know is that low amount of solar activity means cooler temperatures. So we know that's happened before and we don't know what could have happened in the future. So this is the time frame which would have been the little ice age when things were a little bit cooler than otherwise. Now there have been other changes in the past. We know that but it's difficult to model and to see the impact from solar activity. And that means there are other reasons for this or do we need newer models to be able to explain what is going on. So continued research will be needed and more data to be able to see what the sunspot cycles are like in the long term. So let's finish up here with our summary and what we looked at is that solar activity does show itself in a variety of ways. We looked at things like prominences and flares and coronal mass ejections and how they look on the sun and how they can possibly impact the earth. And the solar flares and the coronal mass ejections are what do impact here on the earth and they could cause potential damages to electronic devices. They also cause more spectacular things like the aurora. So those are caused by those and the aurora will be more intense during the time of a solar flare or a coronal mass ejection ejected in the direction of the earth because there are then more charged particles striking us. We also note a possible connection between solar activity and the climate here on the earth but it is not a certain connection. Not something that is still being researched to be able to better understand. So that concludes our lecture on solar activity and space weather. 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.