 Greetings and welcome to the Introduction to Astronomy. In this week's special topic, we are going to talk about the zodiac and what that actually means in terms of what we study in astronomy. Now, we often associate the zodiac with astrology. So, what do we mean by that? Well, astrology and astronomy were actually the same thing a thousand years ago, or even a little less. So, the people who studied astronomy were also those who did astrology. Now, the zodiac is actually those constellations that are located near what we call the ecliptic. The ecliptic is the path of the sun in the sky. So, that means that these are the constellations that the sun, the moon, and planets will actually pass through over the course of a year. Now, they are constellations that are important because of where they're located, not because they have bright stars in them. Certainly, some of them do have bright stars, but that's a handful of these constellations that have relatively bright stars. Many of them are very, very faint constellations. Now, you may also be familiar with a 13th zodiacal constellation, which would be the constellation of Ophiuchus. Ophiuchus located near Scorpius. Scorpius is actually very briefly passed through by something like the sun, and in fact, the sun zips through the little bit of Scorpius that it passes through over the course of about a week, and it will spend much longer in the nearby constellation of Ophiuchus. So, what do we see in the sky when we look at these? Let's go ahead and look at a map of the sky that shows these. And here we have all the constellations, or nearly all of the constellations that we can look at here at once. And we see Aquarius, Capricorn, Sagittarius, and Scorpius. Here is Ophiuchus up here. So, when the sun passes through, it actually passes through far more of this constellation than just the tiny bit of Scorpius that reaches up there. And then as we travel through, we go through the rest of the constellations over here, up to Ares, and we can see these in this nice panoramic view showing all of the constellations of the Zodiac. You'll note that they're not related to our galaxy. Our galaxy is tilted at various regions, and we see some areas such as around Scorpius and Sagittarius here that are close to the Milky Way, as well as Gemini and Taurus over on this side. Others are not located near the Milky Way at all. And if you notice one constellation missing here, you can't really photograph all of these constellations at one time. And that is because there are...the sun is there. And one of these constellations will always be in the same direction as the sun. And you may note that Pisces is actually missing here. But in reality, when we talk about the Zodiac, we are really, in an astronomical sense, talking only about those constellations that happen to be located near the path of the sun. And they are important because the sun, moon, and planets will pass through these constellations over the course of a year. So let's go ahead and finish up with our summary. And again, just to review what we just talked about, the Zodiac is the set of constellations along the ecliptic. These are the ones that the sun, the moon, and planets pass through. They are not the most prominent constellations necessarily, and they do not contain the brightest stars in the sky. Some of them do have bright stars, others are relatively faint stars. They are really important because of their location in the sky, which makes them important because they are the locations where we will find many of those solar system objects. So that concludes this lecture on the Zodiac. We'll be back again next time for another Topic in Astronomy. So until then, have a great day, everyone, and I will see you in class.