 Greetings and welcome to the Introduction to Astronomy. In this lecture, we are going to talk about some more of the debris in the Solar System, including the Kuiper Belt, and one object within that, named Arakoth, which is one of the few objects that has been explored that far out in the Solar System. So, let's go ahead and look at the Kuiper Belt, and we talked about the Kuiper Belt before, the objects orbiting out beyond Neptune. Sometimes they're also called trans-Neptunian objects, anything out beyond Neptune or TNOs. And there are also some objects called centaurs, which orbits near the outer planets, so we have a couple different types of objects here that we look at. The first of these kind of things that was discovered was Pluto. So, Pluto was discovered in 1930, Chiron was discovered in 1977, which orbits between Saturn and Uranus, and we see the orbit here of Chiron in there, actually going in between, inside the orbit of Saturn and slightly outside the orbit of Uranus. And then we had Folas discovered in 1992. We now know of thousands of these objects, so there's a lot of them that are known now that were not just not that long ago. Now, what are the largest ones of these? Well, we've already mentioned the dwarf planets. We've talked about some of those. The four dwarf planets are the largest trans-Neptunian objects, and that includes Pluto, Eris, Makemake, and Homea. Those are the ones that are classified as dwarf planets. There's a few others that may meet the criteria and may eventually be classified as dwarf planets we see here as well. However, Pluto is the only large object of these that has been explored so far. And here we see Pluto as seen by the New Horizon spacecraft when it flew by in July of 2015. Now, that was part of the New Horizons mission, and the New Horizons mission was launched in 2006, and it was a nine-year journey to Pluto. However, the mission was also extended. So the idea was now that we've explored Pluto, is there any other object in the area that's on the trajectory that the craft is taking that will allow it to be able to make another visit now that the craft is there. And we see that here that the path was taken from Earth out in towards toward Pluto, and then New Horizons now being right here and passed by Eracoth, which was another object. It was known as 2014 MU69 before it was formally named. So interestingly, you'll note that it was launched in 2006. We didn't even know about Eracoth until several years later while this was mission was ongoing. So we'd happened to have discovered it, and it happened to be in the right positioning for New Horizons to be able to make a second visit. Now, what do we know about this object? Well, we knew very little about it before because it was just a small blip of light, and you'll see it here, and you can watch as this animation takes you in through the New Horizons as it heads toward this object, and we'll continue to head in, and you can see the object slowly moving there now. And as we get closer and closer, you'll see it start to take some kind of shape as we're able to see some more detail. And you'll see that now it starts to have some detail. And we can see the object, and there is Eracoth. It is very interesting. It was flown by on January 1st of 2019, and was, again, the second object out in the Kuiper Belt and the first small object out there to be explored. It was found to have two lobes. So it was multi-lobed. It was not just one piece. It was two. So there was a larger piece that was about 21 kilometers. The smaller, about 15.4 kilometers. It is what we consider to be a contact binary. So it did not form like this with these two lobes, but two separate objects formed, which then hit each other gently and kind of stuck together. And here's how we may think it may have formed, and we can take a look at that. Here, four and a half billion years ago, several objects were forming. Eventually, they collected other material. Two large bodies remained. They were in a slightly decaying orbit, got closer and closer, and eventually stuck together. And they remain that way to this day. That's also interesting. They are small, but they also have a flattened shape. So most things we look at are spherical. These are actually very flattened. So it's interesting, but we really don't know a whole lot about the objects out in the Kuiper Belt. We have to study more of them in order to be able to study them and get any kind of good statistical studies as to whether Aracoth is just an unusual object or whether they're all like this and help us get an understanding of that part of the solar system. So we've explored far more in the asteroid belt, much closer to us. We've had a number of asteroids visited, but we've explored far less out in the Kuiper Belt and are still learning much about what happens there. So let's go ahead and finish up with our summary. And what we've looked at, we looked at the Kuiper Belt as a collection of many objects out beyond Neptune. Some of these Kuiper Belt objects has been classified as dwarf planets. And New Horizons visited two of these. It visited Pluto in 2015 and then Aracoth in 2019. So that concludes this lecture on the Kuiper Belt and Aracoth. 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.