 Greetings and welcome to the Introduction to Astronomy. One of the things that I like to do in each of my introductory astronomy classes is to begin the class with the astronomy picture of the day. From the NASA website that is apod.nasa.gov slash apod. And today's picture for October 2nd of 2023, while it is titled Sprite Lightning in High Definition. So what do we see here? Well, here is an image of what is known as red sprite lightning. Now this is quite different than the lightning we're used to seeing. That comes closer to Earth, so lightning during a thunderstorm. And while this is associated with the thunderstorms, it is much, much higher up in the atmosphere. The ordinary lightning that we're used to thinking about occurs between the clouds and clouds or between the clouds and the ground and may only be a few miles up above Earth's surface. Instead, this can be much higher. This could be up 50, 60 miles up in the sky and occur around the time of a thunderstorm. But you have to be able to see well above it. So if you're in the middle of a thunderstorm, you won't see this because there's too many clouds in the way blocking it out. You need to kind of have a thunderstorm off in the distance and you're looking at it from the side. So if there's a thunderstorm way off to the side of you and you can see the clouds, but the sky is clear above you, you can look above and sometimes catch this red sprite lightning. However, it is very difficult a phenomena to see and that is because it is very, very fast. It does not take a long time. In fact, the image that you're looking at is from a video taken and it is fact one frame of that video that lasts one-twenty-fifth of a second. The previous frame and the following frame don't show or show only very low level of the sprite. So it's only this single image of that video that happens to show it. So it goes extremely fast. And in fact, it could be formed from large balls of ionized air up in the upper atmosphere that go down at a very high velocity. They speed down at nearly 10% of the speed of light far faster than anything that we can accelerate here on Earth, at least in terms of, say, transportation. If we wanted to try to move something large that fast, we would not be able to do it. We couldn't move any kind of vehicle or airplane or spacecraft at anything close to 10% of the speed of light. And then we get the streaks again as you get some upward streaking balls of ionized gases. But it's a very, very fast process. So being able to catch it, and that's why it was not actually photographed for the first time until the late 1980s, and has then been studied over the last couple of decades a little bit more to learn more about this process going on in Earth's upper atmosphere. But again, very difficult to catch simply because it is a very fleeting phenomena. So by the time you see it and try to take a picture, it's way too late. You have to already be filming in that area and looking for the conditions that are right for the red-spright lightning to occur. So that was our picture of the day for October 2nd of 2023. It was titled Sprite Lightning in High Definition. We'll be back again tomorrow for the next picture. So until then, have a great day, everyone, and I will see you in class.