 Greetings and welcome to the Introduction to Astronomy. In this week's Astronomy of Other Cultures Lecture we are going to continue talking about Babylonian astronomy and specifically look at the star catalogs that the Babylonians developed. So let's take a look at these and these are actually give us some of the very earliest known star catalogs dating back to the 12th century BC. So we think about what this means, 12th century BC we're talking over 3,000 years ago. Now these were then recorded on clay tablets and were done in what is called three stars each. And what does that mean? Well there were three stars for each month and the stars that were cataloged were along the celestial equator giving us a total of 36 stars that happened to be located in that direction on the sky. Now a slightly more recent catalog, the mole apen, was between about 1,300 BC and this was based on far more accurate observations. So still recorded on the same types of tablets and was divided the sky into 71 stars and constellations. So in this case the constellations of the zodiac which would be the path of the sun through the sky there were 17 to 18 constellations. Some of these are very similar to our modern constellations. So some things like Taurus and Leo are two of the constellations that we still use today that are based on these early Babylonian star catalogs that date back over 3,000 years and are really the first recorded star catalogs that we have. Certainly people looked at the stars before, may have named them, but this is the earliest recordings that still survive today for us to be able to study what the early astronomers knew about the sky. So let's go ahead and summarize here and what we've looked at is that really these Babylonian star catalogs are the oldest existing catalogs known. The earliest one grouped three stars for each month are along the celestial equator and the mole apen updated this giving us with more accurate observations and has some of the basis for our modern zodiacal constellations. So that concludes this lecture on the Babylonian star catalogs. We'll be back again next time for another discussion of astronomy of other cultures. So until then, have a great day everyone and I will see you in class.