 Greetings and welcome to the Introduction to Astronomy! In this video I am going to walk through the observation project that you have for this semester and tell you a little bit more about it. Now I'm not going to read through all of the instructions and details here, I'm going to try to hit the high points to be able to get you started. So there's a lot of information here that you can read through, but really in order to be successful the keys are that you really need to be able to get this started early. The idea is that you're going to be making observations of the sun. And what that means is observations of the shadow cast by an object. So if you have your object here and the sun is up off to the side someplace, so the sun is shining up here and it will shine rays and it will cast a shadow on the ground right here and that is what you're going to be measuring. So I'm going to have you measure that shadow length, that would be L, and the object height and that's really what you need to do over the course of the semester. I ask you to do this about 10 times during the semester and you don't need to, it does not need to be done every single day. Once a week is great, every week to 10 days will easily get you this number of observations required. So you're going to use the data table that I provide at the end or make up your own. But let's go ahead and look down as to exactly what you're going to be measuring and the altitude measurements do need to be made at a specific time. And that is about 12.15 p.m. when you are on standard time, which would be during the winter months generally, or 1.15 p.m. during the summer months and it depends exactly on when the time change is that year as to when those occur. I will post your reminder of course when times do change. This works pretty well as long as you're any place around central Pennsylvania. So as long as you don't go too far from that, then you're actually going to be fine. You don't need to worry about the changing a different time. Now if you're in a different location for very far east or west of that, then you may want to reach out to me and we can look up and determine what kind of times are going to be best for you to be making your observations. And I also ask now that you do take a photo of each observation. Now that's just a picture of your object with the shadow being cast and your ruler set up to measure the shadow. You want to submit these at the end of your final write up. I'm going to have you show a picture with your first submission, but you will need one for each observation that you make. So just make it a habit of snapping that photograph, which will also give you that permanent record of that as well. Now in order to get the most accurate measurements, you're going to need to set your object on a very solid surface. So you don't want to put it in the grass. That can make it a little more difficult to measure. You also want things that can be easily measured. Now let's take a break from here. We'll come back to this in just a second. But let's look at the types of objects that you want to be able to observe. So here is an example is for box measurements. If you're using something that is like a box, you want to measure it as shown here in the first one. See how it starts right at the end and then measures outward toward the shadow. Note how the box is turned so that the shadow comes straight back from it. And you get little to no shadow along the sides. You don't want to measure the long way as shown in the middle photograph here. And while this one is actually not bad, some of the problems here are the way it's turned is trying to determine exactly where you want to measure the shadow. What point do you pick and what point do you get here? So the fact that this is kind of curved makes it a lot harder than when you get a nice straight edge to the shadow like this. So it really just depends on how you want to do it. So this one can work. It really have to be a little bit more careful though when you're making that measurement. Now, if you're measuring say something like a can instead, there are the way to measure it is as is shown in the first one here. And that is measuring from the back right here and then measuring forward right to the edge of the tip of the shadow. Note how it's rounded and you want that very tip. But you also do not want the shadow that goes along the side of the image there. You only want the shadow from the very back corner here to the tip of the shadow. You don't measure underneath the object as shown here. And you don't measure that shadow along the side of the can as shown in the last measurement here. You'd only want to measure from right there to the tip of the shadow. That would be your shadow measurement if you're using a can. Now, if there's some objects to not use, a can or a box works really well. But there are some things that you don't want to use and it's just because they're very irregular shapes. Note the irregular shape here. This is not something that you'd want to use. Where are you measuring the shadow from? And where is the end of the shadow? You've got to be very careful as to exactly what you're measuring here. An object like the chair here is very difficult because it's got a very irregularly shaped shadow. And the giraffe here, same kind of thing. When you're measuring the shadow, it's hard to determine exactly where that shadow starts because the shape is not regular. Again, try to stick with a box or a can. Any of these are not going to work well and are not going to give you accurate measurements. You also need to make sure that you're measuring the shadow along the bottom. So you don't want to measure the shadow in this direction. You don't want to measure it at an angle going down. The shadow that you want is the shadow along the ground. That is what we are measuring. So you don't want to measure it at an angle. And you also don't want to do an object that you have to hold up. It's very easy to tilt this a little bit one way or the other. And unless you have a level there to make sure you have it exactly straight up and down when you're making your measurement, that can throw your values off a little bit. So those are some things just to watch out for when you are actually making these measurements. So that's what we want to measure here. Now that's all you need to do for right now. You do not need to worry about anything else. Once you make those measurements, I show you how to start the calculations here. So there is some trigonometry involved. But again, all it inquires knowing is which buttons to push on the calculator. And I will give some demo videos that explain that for you later. You also need to know the latitude of your location. For most regions around hack, we can use Harrisburg and it works out very well. And that would be 49.75. The latitude of Harrisburg is about 40.25 degrees. This is what we call the co-latitude or 90 degrees minus the latitude. And that is what we will need for the calculations. However, again, you need not worry about this till the end of the semester. And I will give you far more details on this later on. I do look for 10 observations. Now that is for a full semester class. For shorter classes, that will be adjusted. You do want to record everything in the same sets of units. So if you're measuring in inches, that's fine. Don't try to convert them into centimeters. If you're measuring in inches, make sure you measure your object height and your shadow length in both in the same sets of units. And we will look. I also give you some sample questions. You're going to need these for your write-up. But there's some things for you to think about as you get started. So I also will give you some breakdown as to the final report. I'm going to go over that in far more detail later in the course. But you could read a little bit about it here. And this is what your final write-up is going to look like. So I'm giving it to you now. You don't need to do any of this right now. This is just to give you a chance to look ahead. The only things you really want to look at here are the part on the data, which is number three. So again, you need a photo of each observation. I ask you to do three days in between observations. So don't make them seven or eight days in a row. You can. Those are fine as extra observations. But for me to count those 10, I am looking for two full days in between the observations. So February 1 to February 4, I only give you credit for four observations in any individual month. So the idea there is to get them spread out over the semester. Here I tell you that if you're in a 12-week course, you're getting eight, six-week course, five, and the four-week course looking for at least three observations. Again, you can always make extra observations. So if you want to make an extra 10 observations and make 20 of them, I will look through everything that you submit and grade those. Do not make up data. Make sure you are not making it up. If you don't make the observation, don't make the observation. Please note, 30 points is all the data are worth out of 160. And 15 of these will be given during the semester. So you could make three observations that could give you up to half of that credit. It's not worth faking the data and getting caught and risking a zero grade on the entire assignment. So if you don't get observations for a while, that's fine. Just don't try to make up them. I've had to give people zeros on the project. It's never fun, but I can't just let something like that go. In order to get credit for them, you do have to submit the observations during the semester. I collect them three times during the semester. And if you do not submit the observation, then you don't get credit for it. So if you make five observations in September and only submit one of those, you will not get credit for the other four at the end of the semester. Also, if you do not get credit for the data, if you use only my data, I will be providing some data. That's fine. If you don't make any observations, you just lose this 30 points. And you can still do the rest of the write up and get the rest of the points, even if you make no observations. So let's go ahead. I'm not going to go through the rest of the details here again. We can look at that later in the semester. But that just gives you idea if you want to look ahead. Now, here is a data table. And I provide different copies of the data table for you in different formats for whatever you want to use. What you want to record right now is the date, the time, your location. You can tell me what city you're in. You can give me a zip code. Just something that tells me what your location is. That does not have to be the same if you make observations from different locations. That way we can see if there's a reason that some observations don't quite fit in. What were the sky conditions like? What is your shadow length and what is your object height? These are the only things you need for right now during the semester. The rest of this will be completed at the end of the semester. And I will provide additional information on how to go about doing those calculations. I give you a room for 20 again for most classes only the first 10 are required as long as they are spaced out as given in the handout there. So that concludes this lecture video on the solar observation project that you will do over this semester. We'll be back again next time to continue our introduction to this course. So until then, have a great day everyone and I will see you in class.