 Greetings and welcome to the Introduction to Astronomy. In this week's special topic in astronomy, we are going to talk about geosynchronous orbit and what that means. So what is a geosynchronous orbit? Well, this occurs when the orbital period of a satellite is the same as the rotational period of Earth. And what that means is that it always keeps over the same spot on Earth. Now this is, it will say, you can see this here, if you can see the red line here as it goes through, that kind of connects, not directly, but it's staying over this exact same point as it orbits. So exactly as fast as Earth spins, the satellite orbits around. Now this is a relatively high orbit. Many things are in low Earth orbit, such as the space station, international space station, which orbits Earth once every 90 minutes. And we'll see all different parts of Earth over the course of an orbit. An orbit in a geosynchronous will stay over the same portion of Earth. Now if it's in geosynchronous, it can change its position slightly. So the ones that are actually very interesting are what we call a geostationary orbit. That is a geosynchronous orbit that orbits over the equator. When this occurs, then the object will, the satellite will stay at the same position in the sky. So you could look out, it will always be in the exact same spot on the sky. Now why is that so useful? Well, it's useful for things like communications, television, and weather if you want to monitor certain areas. So if you want to be able to monitor storms in the Atlantic, it's very convenient to have a satellite dedicated that is up over the can view that specific area. It's also useful for things like satellite communication. So satellite dishes such as this, that can be used for various types of communication for satellite TV, are important because you can then point it just to that one spot in the sky. Once it's all set up, then you don't need to track the satellite. So if you wanted to follow the international space station, you'd only get to see it for a short period of time when it was up above your horizon. The satellite dish would have to be able to move to track that position. When you have something in a geostationary orbit, then it stays exactly in the same spot. Your satellite dish can just be pointing to that satellite, and you no longer need the complexity of being able to track something around in the sky. So let's go ahead and finish up with our summary and what we looked at this time. We talked about a geosynchronous orbit and a geosynchronous orbit occurred when the satellite orbits at the same rate that Earth rotates on its axis. If this geosynchronous orbit is over Earth's equator, it will be geostationary and remain at the same position in the sky. These are useful for things like communication and weather satellites as we previously discussed. So that concludes this lecture on geosynchronous orbits. We'll be back again next week for another special topic in astronomy. So until then, have a great day everyone, and I will see you in class.