 Greetings and welcome to the Introduction to Astronomy. In this week's Astronomy of Other Cultures, we are going to look at Maya Astronomy and specifically look at the region of Chitsune Itza, and we'll see what we can understand and what we can learn about Maya astronomy from this region. Now this is actually contains a number of different things, and in fact the region contains that one of the Maya pyramids known as El Castillo kind of centered in the image here, and we also can see the observatory El Caracol, which is down a little bit further down here, and of course you can see that there's a number of other buildings here as well that are also other temples and other things related to the different observations that could have gone on here. So first of all let's look at El Castillo, which is one of the primary pyramids of Maya civilization, and could have some relationships to various observations. In fact if you count the steps and counting the very top step, there are a total of 365 steps. Now that's not on each, we see one section here, but there are similar steps on every side, and if you count up those total number of steps, it ends up being 365. Is that related to the number of days of the year? It lines up, but is that the reasoning? Of course we don't know. There are possible alignments with things like the Sun, the Moon, and the planet Venus, so are those related as well? Could those be a part of how this temple and this pyramid was constructed? And one of the more interesting things that come up in one of the prominent things that people go to see is the serpent that appears. Now here we see an image of that, and you can see a serpent head down at the bottom, but at the right time on the equinox you actually get this wavy shadow like the body of the serpent, and as the Sun moves that will seem to move and progress down the pyramid. So the question is again with all of these, are these designed this way? So were these designed to be, or are they just coincidences? And of course we don't have records of the construction as to what each of these things was supposed to mean. So it's certainly very interesting that we have these alignments such as we do with Stonehenge. We also have the number of steps matching 365. Is that just a coincidence? And the patterns that appear just on the equinox, is that, was that planned? And we don't know whether it was planned or it just happened to come out that way because of the alignments of the pyramids. So it's a very good question as to whether or not these are what was intended by the Maya who built this area. Now we can also look at the observatory and the observatory here is El Caracol and that it was built almost over a thousand years ago now. And we can find there are sight lines for positions of the equinoxes and solstices. Now these are very prominent times and we see them across various civilizations that have line things that line up with these. The equinoxes when the day and night length are equal in the solstices. Summer solstice when the sun reaches its highest point in the sky and the winter solstice when the sun would reach its lowest point in the sky. So those are both very prominent. One of the more interesting things with the Maya civilization is that they knew the cycle of Venus very precisely. It's a 225 day cycle which means that five Venusian cycles make eight Earth years. So the extremes of Venus in its position in the sky will reoccur in eight-year intervals and this is something that ties into a lot of the Maya observations. Now we see the pyramid and the observatory after they have not been reconstructed but kind of reclaimed from the vegetation that had overgrown them over time. So they had been lost essentially for a while and then now reclaimed as a major tourist and research area to research to better understand the astronomy of the Maya. Let's go ahead and finish up with our summary. We're looking at the Chitsune-Itsa region which contains a couple of different structures related to Maya astronomy. We looked a little bit at El Castillo, one of the Great Maya Pyramids, and El Caracol, one of the early Maya observatories and we did see how many things there were based on cycles of Venus which is of course the most the brightest star-like object in the night sky. So that concludes this lecture on Chitsune-Itsa. We'll be back again next time for another astronomy of other cultures. So until then, have a great day everyone and I will see you in class.