It is late November 2015, and Professor Turing is carrying a few newspapers, all of which prominently feature an astronomical event on the front page. He also happens to be wearing a traditional Athabascan beaded vest over his Muggle-style dress shirt, which was his way of celebrating the American holiday of Thanksgiving. As students enter the room, he hands each student his or her graded midterm.
Good evening, students. Congratulations: the majority of you have done very well on your exams! Remember, if you do not understand why you lost points, please contact me or one of my PAs. We are here to help you.
Today, we will learn how to use the magical telescope to measure the albedo and the size of the Moon. Then, we will learn about a few planets that you can currently see in the sky; the late part of November 2015 is, luckily, an excellent time for looking at planets. Sadly, these planets are visible during times that we do not have class, so we will learn about them during the lesson, and you will be asked to view them for homework.
Telescope Use: Measuring an Object’s Size
Magical Telescope Diagram
Drawn by Professor Turing
Please look up at the Moon without your telescope. How big is the Moon in the sky? It is hard to measure the Moon’s apparent size with our naked eyes. Luckily, we have our magical telescopes to help us.
While the telescopes that we are using in class are basic models, they have quite a few useful features. For example, you can use the telescope to measure the size of an object in the sky. Since the Moon is visible today, let’s measure the size of the Moon. First, point the telescope at the Moon and zoom in. Remember, the zoom controls are on the left side of the telescope - the large knob is for large adjustments, and the small knob is for smaller adjustments.
Then, locate the button, which is labeled “S” for “size”. You can find it on the right side of the telescope. Then, push down the button. A ruler will appear in your view - estimate the size of the Moon based on the markings of the lens.
Let’s point our telescopes at the Moon and take a look.
One great thing about this ruler is that it it will zoom in and out as you zoom in and out of the Moon. Remember that the ruler that appears in your lens always measures the size of the Moon as if it were to be seen with a naked eye. For the best results, zoom in as close as you can. As you zoom in, the magical ruler that appears in the lens will show more detailed size increments. You can also see your current magnification level displayed on the upper right side.
Zoom in and out slightly on the Moon and see what happens. Good job, everyone!
Notice how much easier it is to use our magical telescopes than our naked eyes? More complex models of telescopes contain additional magical functions. For example, higher-end models will let you measure the size and other attributes of extraterrestrial objects by saying aloud the quality that you wish to measure. The words will trigger the appropriate charm in the telescope to show the appropriate scales on the screen.
Let’s now discuss how to use your telescopes to measure an object’s albedo.
Telescope: Measuring an Object’s Albedo
Measuring an object’s albedo is rather similar to measuring an object’s size. As I mentioned in a previous lesson, magical albedo is a measure of how much magic is reflected off the surface of an astronomical body - the lowest value possible is “0”, which refers to complete absorption of magic by the surface, and the highest possible value is “1”, which refers to a complete reflection of magic right back at us.
All you have to do is push down on the button with the “A” marking. When you do, the object that you are looking at will turn different shades of green depending on the albedo. In addition, a bar with 10 different shades of green will appear on the side. The shades of green are arranged from light to dark, with the darker shade standing for lower values and the lighter shade standing for higher values. For example, the darkest shade stands for readings of 0.0 to 0.1, the next darkest stands for 0.1 to 0.2, and so on.
Let’s take a look at the Moon. Notice that the bright parts of the Moon have high albedo, while the dark parts of the Moon have low albedo. Also, notice how much of the magic that gets reflected back at the Earth comes from locations with high values. I am going around and checking on everyone in class - if you have a question, please let me know.
Now, we will be going over our assignment for next week.
Viewing the Planets
Image Credit: EarthSky.org
One challenge when teaching Astronomy is that the objects that we will be looking at may not be visible to us during our class period on Wednesday night. It turns out that the second half of November, for example, is great for viewing only a few planets. Three of them - Venus, Mars, and Jupiter - are visible right before dawn. Sometime before this class and next class, I would like you to go out and view these planets.
I have given everyone temporary passes for permission to be out in the castle around dawn. Please bundle up as the temperatures around that time may be chilly for some, and feel free to bring a classmate or several to the viewing party. I will post this chart here in front of my office and by the southeast corner of the Tower so that you can be reminded of where to look.
Finding the planets is very easy. First, locate the constellation Corvus - it should be in the southeast portion of the sky. Then find the star Spica, which should be left of the top two stars in the Corvus constellation. We will learn more about Spica in future years. The three planets should be aligned on the diagonal, with Venus being the lower planet, Mars being the middle planet, and Jupiter being the planet in the upper part of your view.
I will be in the Astronomy tower on Wednesday and Friday morning at dawn. If you have trouble finding these planets, please come seek me out, and I will help you. Bring your friends and housemates if you would like. This is important, as next lesson we will be learning a little more about these planets and their moons.
Thank you for your time. I will see you next Wednesday. Class is dismissed.