 Greetings and welcome to the Introduction to Astronomy. In this week's Women in Astronomy, we are going to introduce this topic that we will be covering over the next few months. And I will be talking about a number of different contributions by women in astronomy over history. So let's go ahead and take a look at some of this here. And one thing that we will note is that women have always played a big part in astronomy, and we will see that over the coming weeks as we go through some of these earliest astronomers. And here we see Hepatia of Alexandria going back 1,500 years as one of the very earliest astronomers, mathematicians, who really provided a lot of work back then. And we will look at a number of astronomers in much more detail. Now, we do understand their contributions were not always well appreciated at the time, and we will see that in many cases where that has happened. However, we do want to look at the contributions that they have made and how they have increased our astronomical knowledge. Now, for the purposes of this series, what I am going to do is I'm going to go back as early as we can possibly find documented evidence of women contributions in astronomical research. I am going to cut this off at the mid-20th century, and what I've defined by that is earlier had to be born before 1930. So that's just an arbitrary cutoff that doesn't mean that everything changed then, and all of a sudden the women were accepted into astronomy after that point. It's just giving me a point to cut this series off, and that's just kind of my arbitrary date that I have chosen. So astronomers born before 1930 will be included. Anyone born 1930 or later will not be included, at least not in this series. Now, we can look at a couple of examples of this. For example, we will see Annie Cannon pictured here who pioneered a lot of spectral classification. How do we classify the stars based on their spectra, splitting them into their component colors of light? So a lot of that work was pioneered by her and by other female astronomers. In addition, we will look at more recent astronomers such as Vera Rubin, who pioneered our understanding of dark matter, and that a lot of the material in galaxies that makes up galaxies is some kind of material that we cannot see directly through ordinary means and can only detect it through its gravitational effects. So let's go ahead and summarize what we're going to go over a little bit here. And what we've said is that I've mentioned that women's have been active in astronomy going back over a thousand years. This series will discuss some of these astronomers and their contributions, and it is not meant to be complete. I can't say that I will cover every woman astronomer, but I'm going to try to hit a variety of them going back over the course of this time period. And that time period will be back as far as we can possibly go up through about the mid-20th century, and as I've said, I've defined that as 1930... astronomers born before 1930 as my cutoff as to what I'm going to use for this current series. So that concludes this lecture on women in astronomy. We'll be back again next time for another topic. So until then, have a great day, everyone, and I will see you in class.