 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.apod. And today's picture for November 13th of 2023, well, it is titled Andromeda over the Alps. So what do we see here? Well, this is the Andromeda Galaxy, and you've certainly never seen it like this before because it can't be seen like this to the naked eye. The only way to get this is with a photograph. Now you can't even get it with a single photograph because you would not be able to take a long enough exposure of the Andromeda Galaxy and not vastly overexpose the mountains in the foreground. So you have two very different brightnesses here, and in order to do this you had to have a couple of different images that are then put together. So they were taken from the same location, same camera, and everything was identical, but you took one and get the foreground, and then you take another much longer exposure to bring out the vast detail in the Andromeda Galaxy. Now the Andromeda Galaxy is the most distant object that can be seen with the unaided eye, and it won't look like this again, but you can see a fuzzy patch in the sky if you know the right place to look in the constellation of Andromeda. Now we're seeing it very distant, it is about two and a half million light years away. And that means what? That means we do not see it as it is today, but as it was two million years ago. Has it changed? Not in any significant manner. These do not change on such a short time scale as only a couple of million years. However, if that does not mean that there have not been stars that have gone supernovae, and we just don't know about it yet. If one became a supernova a million years ago, we still have a million and a half years before that light will actually get to us here on Earth. Now the Andromeda Galaxy, this is a scene that is actually upcoming that you would be able to see with your naked eye, but not for several billion years, and that's because Andromeda and our Milky Way are actually getting closer and closer together. So at some point, billions of years from now, a view from within our Milky Way might see something like this in the sky, and in fact watch the Andromeda Galaxy appear to get larger and larger. Then what we expect based on the studies that have been done so far is that the two galaxies will eventually merge together. When galaxies merge they will eventually coalesce, but in the collision, which isn't a collision in the sense that you normally think of, gas clouds will collide and there will be a massive burst of star formation, with many billions of stars forming all at once. And then eventually the two galaxies will settle down after another billion years or so, and we will have just one larger galaxy present where we currently have the two, the Milky Way and Andromeda. So something to look forward to, not in the near future, but in a few billion years from now, that Andromeda and our Milky Way will combine together. So that was our picture of the day, for November 13th of 2023. It was titled Andromeda over the Alps. We'll be back again tomorrow for the next picture, previewed to be Planet's Rock. So we'll see what that is about tomorrow. And until then, have a great day everyone, and I will see you in class.