 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 30th of 2023. Well, it is titled Reflections of the Ghost Nebula. So what do we see here? Well, looking toward the constellation of Cepheus in the northern sky, we see what is known as the ghost nebula. You can kind of get an idea of that ghostly apparition out in space here. Now what we're actually looking at is a very dusty area in space and that is dust that is a little bit larger particles than typical atoms or molecules. So it is not the same as dust that you may be used to in terms of household dust, but it is somewhat a little bit larger particles than individual atoms or molecules that make up most of the gas in space. Now within a nebula like this, we are seeing signs of star formation. And as you look through the nebula, you'll see some areas that are darker and denser than surrounding areas. The lighter areas around it are better able to reflect and scatter light around from the stars, but the darker denser areas are where stars are still in the process of formation. And within those dark dense knot, gas is collapsing. Gas and dust will collapse down into what we call protostars, objects that are becoming stars but have not quite gotten there yet. In order for something to actually become a star, it has to get hot enough in its core to be able to fuse hydrogen into helium. And once it can do that, it is officially a star. And before that, we call it a protostar because it is in the process of formation. And once it does actually form, it will then begin to break out of its cocoon. The immense amount of energy that it is releasing will then clear away a lot of the material. So emptier areas around bright stars that have already formed are pushing away and eating away at the material that remains. And eventually, all we'll have left here is a cluster of stars. And the rest of the material will slowly dissipate over hundreds of millions of years and again, leaving behind just that star cluster. Now star formation will not end there. It will continue. It will just move through more of this molecular cloud complex. So while it may end in one area, it will continue on in others. And that is what happens in something like our galaxy, which is a spiral galaxy. And a spiral galaxy has a lot of cold gas and dust that is able to form many stars. So star formation is an ongoing process in a galaxy like our own. So that was our picture of the day for October 30th of 2023. It was titled Reflections of the Ghost Nebula. We'll be back again tomorrow for the next picture, previewed to be a Devil on Mars. So we'll see what that is about tomorrow. And until then, have a great day, everyone. And I will see you in class.