Even though it is nighttime, students are excitedly talking to each other in the Astronomy classroom. As Professor Turing walks into the room, he opens the curtains to reveal a beautiful view of a gibbous moon. He places a single half-page of notes as well as a cup of water on the desk that is located in front of the classroom. 

Good evening, students. I am very pleased to report that the class has done well on the assignments from last week. Many of you have attempted the extra credit, which makes me very happy. For those of you who have not done the extra credit yet and still wish to complete it, please do so - although it is optional, the extra credit is very easy, and it will also help both you and me make this Astronomy class a better experience for us all.

I am glad to see that everyone has brought a von Rheticus-model magical telescope to class. If you have not removed your telescope from its packaging, please do so now.

Magical Telescope Safety

Now let’s talk about magical telescope safety. Your telescope is a fine magical instrument, and you should treat it with respect. This means no play fighting with them, no flinging them across the room, and no leaving them outside in the elements. Of course, common sense also applies here. For example, do not use a telescope in dangerous environments. While it is common to stay still while observing the skies, if you should have to take a step in either direction, pay attention to where you are walking.

In fact, the glass lenses on the telescope are extremely fragile. There are scratch-resistant and break-resistant charms on them - however, you should still keep the lens caps on just in case. In order to ensure that you do not lose your lens caps, each telescope has the lens caps tied on to the sides of the telescope with a string, and each string is attached to the side of the telescope with a Sticking Charm. On the outside of the larger lens cap, there is a place to write your name - feel free to do so now if you have not done it yet. This will ensure that your telescope will be returned to you if it were to get lost. Broken lens glass may feel like Muggle broken glass, but broken Muggle glass is still dangerous. If you do have a lens glass break on you in class, call me, and I will take care of it. Usually I can fix your lenses with a spell.

You should note that there are two astronomical items that you must not look at with your magical telescope. The most dangerous item to look at with your telescope is the brightest object in the sky - the Sun. Looking directly at the Sun with the naked eye - in other words, seeing the sun without using the help of another instrument to “zoom in” on the Sun - could result in irreversible damage to your eyes. Looking at the Sun with a telescope will also damage your eyes as well as the magical functions of your telescope.  In other words, the telescope will function like a Muggle telescope if you point it at the Sun. Solar eclipses are even more dangerous for your eyes and for your telescopes. Keeping the lens caps on the telescope will prevent the telescope from reaching this fate.

Remus Lupin and his full Moon boggart. 
Source: Harry Potter Wiki

The other time that you must not look at directly through a magical telescope is the Moon during a full Moon. Of course, unlike the Sun, the Moon can be safely seen with the naked eye. However, the light from a full Moon contains so much magical energy that, if light from the full Moon manages to enter directly into the telescope, it will not only destroy the magical properties of a magical telescope, but it will also physically crack the glass lenses of the telescope. Remember that a full Moon is powerful enough to transform werewolves. In order to prevent the light of the full Moon from entering the telescope, please use a lens cap when carrying around your instrument. We will discuss why this is the case in a future lesson.

How can you figure out the phases of the Moon so you do not accidentally use the telescope on a full Moon? You can, of course, look outside yourself. If you would like to know the phase of the Moon on a future date - say, for a stargazing party - you could use a Moon chart or a Lunascope. A Moon chart is just what it sounds like. While these are handy to predict the phases of the Moon, they have a steep learning curve. Lunascopes, on the other hand, are easier to use but much more expensive. We will have more experience learning how to use these items in future years of this class.

Today, we will be looking at the Moon. Take your telescopes, grab a quill and parchment, and come with me to the viewing areas of the Astronomy Tower.

Lunar Viewing

Today’s View of the Moon
Image Source: University of Illinois Astronomy Department

When it comes to looking at the objects in the night sky, many budding Astronomers - Magical and Muggle - love to view the Moon. So much can be seen even without a telescope, and even more of the details can be seen with a telescope. Today, the Moon is in a waxing gibbous phase. One interesting thing to note is that while the Moon appears to be lit, it does not produce light on its own. The light that you see coming from the Moon is actually reflected from the Sun. More discussion about the magical properties of moonlight will be covered next lesson.

Most of you have seen, at least from observation, that the Moon comes in different phases. In the new Moon phase, the Moon is not visible to us on Earth. Gradually, a sliver of Moon starts to appear - this is the waxing crescent phase. When half the moon is visible, the phase is called “first quarter” because it is the beginning fourth of the 30-day lunar cycle. The Moon then goes through a waxing gibbous phase until it becomes a full Moon on the fourteenth day of the cycle, and then the Moon’s visible area starts to shrink - waning gibbous, last quarter, waning crescent, then new Moon.

Phases of the Moon. 
Source: Wikipedia

Here are some hints for observing the Moon. The word “waxing” means growing, and the word “waning” means shrinking. Here in the United Kingdom, as well as anywhere in the Northern Hemisphere, if the right part of the Moon is lit, the Moon is waxing, and the visible part of the Moon will be growing in size in the next day. If the left part of the Moon is lit, the Moon is waning, and the visible part of the Moon will be smaller in size the next night.

Observing the Moon by naked eye and by telescope in the gibbous phases - as well as by naked eye during the full Moon - is ideal. You can see the many details on the moon during the gibbous and full Moon phases. In addition, the Moon rises and sets at different times according to the Moon’s phase, and gibbous and full Moons tend to be visible deep into the night - which means that many of the Moon’s fine details are visible and not washed out by sunlight.

Now, let’s quickly go over how to use our magical telescopes. Today, we will be learning how to use the magnification function of the telescope. First, remove the lens caps from the telescope and point it at the Moon. Turn the large metal knob on the left side of your telescope to zoom in so that the Moon fills up almost all of your field of vision. Zoom in slowly with the small metal knob on the same side. As you zoom in, notice how the telescope uses magic to focus your lenses. The charms in the telescope are able to focus your lenses for you, similar to an autofocus lens on a Muggle camera. Should you need to change to focus of the lens manually, pull out the smaller zoom knob and twist to adjust. Push the knob back into the telescope to turn on the magical focus.

There you have it - the Moon in all its glory, through both a telescope lens and with the naked eye. Practice observing the Moon with the naked eye and through the telescope, and remember to not use the telescope during the full Moon. Also, there are assignments that I would like you to complete for next week.

Thank you for your time, and have a good evening!