 Greetings and welcome to the Introduction to Astronomy. In this week's Misconception in Astronomy, we are going to look at the Moon and talk about whether the Moon is rotating or not. So does the Moon rotate? Well, let's give our quick answer here and we're ready. Yes, the Moon rotates on its axis just like other objects in the Solar System. Every object in the Solar System rotates on its axis. Now sometimes the Moon is thought to not rotate because we always see the same side of the Moon. Now that is also true. One side of our Moon always faces us. But this is not because the Moon is not rotating, it is because its rotation and its revolution are synchronous. They are exactly the same. Let's take a look at an example here and what we see is let's see first of all a rotating Moon in a synchronous orbit. Synchronous simply means that on the Moon, one day, one lunar day, would it be equal to one lunar year? A lunar day is how long it takes the Moon to spin on its axis once. A lunar year is how long it takes it to go around Earth. And those are both exactly the same amount of time. And when you do this, this one location on the Moon will always be pointing toward Earth no matter where it is in its orbit. Now how would this differ if the Moon did not rotate? If the Moon did not rotate then we would be able to see the entire other side of the Moon and let's take a look at that. Here is an example now with the Moon not rotating. So if the Moon were not rotating, this point here that is pointing toward the Earth that this section would be pointing away from Earth there and we would be seeing the other side of the Moon which is simply not visible from Earth. So the Moon has to be rotating in order to allow us to just see that one side. But the rotation is what we call synchronous and when it is synchronous that means that the rotation and revolution, rotation is how long it takes to spin on its axis, revolution how long it takes to move around Earth, those two are exactly the same. Now if they were not then we would be able to see something like this where we would be able to watch the Moon rotate and be able to see both sides of the Moon. We would see the near side as we see it about here and then we could see the far side here. So we would be able to see all of that if we were, if the Moon were not rotating. However because it is rotating and is synchronous with its orbit therefore we'd never see one side of the Moon directly from Earth. So let's go ahead and finish up with the summary and what we found this time is that yes the Moon does rotate. It rotates on its axis just like every other object in the solar system. One side of our Moon faces Earth because of synchronous rotation. The rotation and revolution are exactly the same and that is what is happening here. The Moon spins on its axis at exactly the same rate at which it orbits Earth and that is what causes us to only see one face of the Moon from Earth. So that concludes this misconception on the Moon not rotating. We'll be back again next time next week for another misconception in astronomy. So until then have a great day everyone and I will see you in class.