 Now we're going to take a look at measuring the sun's rotation rate using some sunspots. In order to do that, I've got an image here and I've got a transparent grid that I can place on top of this. I'm going to zoom in just so we can see the numbers a little bit easier. Your latitude is how far north or south you are, in this case on the sun as opposed to the earth, but that's 20, 40, this is minus 20, minus 40. The longitude are the numbers that are going to go around the sun. So you have 10, 20, 30, 40, 50, 60, 70, 80, 90, etc. And we're going to focus in on this sunspot down here. So its starting latitude is probably about a little bit below the minus 20, which actually makes it a little bit minus 20, let's say that would be minus 30, so maybe minus 23. If I were going to look at the longitude, well it's between the 50 and 60, it's a little bit closer to 60, but still kind of close to the middle. So let's call that 57. So there's our starting latitude and longitude, minus 23 and 57. Now to continue, I have to close these images out and grab the ending sunspot image and pull over the grid onto it again. Now the important thing to realize here is that as it's rotated, my sunspot didn't change its latitude much and so this is our new spot, not our new spot, the new position for our same spot. So its ending latitude is still about minus 23, but its ending longitude is about halfway between 120 and 130, so we'll call that 125. Because I know when these images were taken, we're going to be able to take how far it moved in longitude and how much time that took to calculate how fast the sun is rotating. So go back and re-watch if you need to grab your measurements again, but these are the measurements you'll use in your lab report.