April 13th: Edward, Annie, and Williamina Discuss Spectral Classification


365DaysDate: April 13, 2009


Title: Edward, Annie, and Williamina Discuss Spectral Classification

Podcaster: Bruce Palmquist, Feliciti Fredsti, and Marilyn Magenis

Organization: Central Washington University Physics department,

Description: In the late 1800s and early 1900s, Harvard College Observatory Director Edward Pickering hired dozens of women, nicknamed the Harvard Computers, to process and analyze astronomical data. Two of the women, Annie Jump Cannon and Williamina Fleming, developed a classification scheme for classifying stellar spectra. In this podcast, you’ll hear an imagined conversation between three Pickering, Cannon, and Fleming wannabes about the development of their stellar classification scheme and the continual updates of stellar classification.

Bio: Bruce Palmquist is a professor of Science Education and Physics at Central Washington University. He writes a weekly astronomy column for his local newspaper and for the world at http://theellensburgsky@blogspot.com/. Feliciti Fredsti and Marilyn Magenis are physics majors at CWU.

Today’s Sponsor: This episode of “365 Days of Astronomy” is sponsored by Lenore Horner.


Pickering: Edward Pickering here. Yes…. Annie Jump Cannon, Williamina Fleming? Send them on in.

Fleming: Why hello Edward.

Cannon: Hi Edward.

Pickering: Annie. How are you doing? Williamina. I haven’t seen you for…how long has it been?

Cannon: Oh, years now.

Pickering: It’s been a long time, and it seemed like a really long time. I was in desperate need when I first met you folks.

Cannon: Yeah, you were.

Pickering: It was the turn of the century and it was unbelievable how many observations there were. Astronomy was just booming at that time. There were thousands of photographs. Remember those boxes? Just hundreds of pounds of glass plates.

Fleming: Yes I remember that, definitely.

Pickering: Tell me a little bit about your life’s work, especially you Annie. What interested you in Astronomy?

Cannon: My mother. She was so fond of picking out and showing me the constellations and telling me all the stories about them. It was fascinating. I’m really indebted to her for my career in Astronomy. I spent many hours gazing at stars…night and day.

Pickering: What about you Mina? You had a different background.

Fleming: Yes. I was born in Scotland. I married my husband in Scotland and we moved over to America, to Boston. I was a teacher in Scotland and moved to America and he left me with my unborn child. And so I was desperate for a job and fortunately Edward Pickering here, you were able to give me a job as a maid. And from then, you actually gave me a job, a better job, at Harvard.

Pickering: And you did a better job too. At that time I had a male assistant and that person was very lazy, just between the three of us, super lazy. And in fact I told him, I said ‘My maid could do a better job than you’.

Fleming: How did you come about hiring women at Harvard anyway?

Pickering: There were thousands of observations, tens of thousands that needed to be analyzed, and there weren’t enough men around to do it. I had my assistant, and I had a few other men working. But I don’t think I have to tell you folks that women are very good at doing tasks that require extreme concentration. They are very meticulous, and they can do something, and can have the patience to do something, that quite frankly the men just wouldn’t take the time to do.

Fleming: I think women don’t get enough credit for how brilliant they are. I know Annie here, and me we were, we were very intelligent women. We went to school just like the men did, so we have every right to be in the observatory as well.

Cannon: It wasn’t very hard for us to be there, but it was hard getting there. We were met with opposition every step of the way. I remember telling my principal that I, um, wanted to be in this and was rejected, and put down, and there was a lot of social opposition as well. It wasn’t expected of a woman to be in a scientific career. She was expected to be at home, or be involved in the literature aspect.

Fleming: We certainly proved them wrong.

Cannon: Yes we did.

Pickering: How did you feel when your group was referred to as ‘Pickering’s harem’?

Fleming: I didn’t like harem so much, but I didn’t mind computers because you have to remember that back then, we didn’t have the computers that you think of now. We had computers that were people doing calculations.

Cannon: If young men aren’t going to do the calculations, and be willing to do the calculations, and young women are, then the young men have no right to complain.

Pickering: You made 25 cents an hour with raises up to 35 cents an hour and that amounted to about $10.50 a week. Six days a week, solid work, seven hours a day.

Fleming: Ha! A seven hour day that went from 9:00 in the morning to 6:00 at night. Edward, you need to learn how to count.

Pickering: You spent five hours at the observatory but then two hours doing work at home or when, where it was convenient for you.

Fleming: Yes it was certainly convenient having a son very young.

Cannon: It was also convenient living nearby in Star Cottage that was near the observatory.

Pickering: Mina, why don’t you talk a little bit about your classification scheme because what we know of nowadays really came from Annie Jump Cannon, but without your original work in the area, it’s possible that Annie would not have progressed as far as she did.

Fleming: I started classifying the stars from A to Q and as we had discovered more stars we had found categories that seemed to prevail, and some categories that didn’t and so we needed to move categories around.

Pickering: Your scheme was very simple. The interesting thing was somebody else at the observatory, Antonia Maury who was Henry Draper’s niece, she came up with a more complex scheme. She had a scheme in which she classified things in Roman numerals 1 through 21. And it was based on the star’s temperature and also the thickness of the spectral lines. And I have to admit at the time I didn’t really like that idea, although history has shown that was an excellent scheme because the thickness of the spectral line tells a lot about the star. Super Giants have the thinnest spectral line of all. Main Sequence stars have thick spectral lines. Antonia noticed that, but I thought at the time that was too complicated. But Annie helped clear things up. What was your scheme?

Cannon: I spent hours in the observatory um room looking at plates of glass that had photographs of the stars and basically what I was doing was looking at the spectrum of each star and classifying it and most of the classification was actually in my head, I didn’t really have it written down so it wasn’t until Cecilia Pane did her thesis on my work that she actually was able to classify and set into words what my classification scheme was and what she discovered was that my classification scheme was based off the temperature of the star and letters had already been assigned to the spectral lines, but the way I had classified them and organized them into these sequences the letters got rearranged because of the different temperatures of the stars. That is memorized by the mnemonic device “Oh Be A Fine Girl or Guy Kiss Me” and each of those stand for a spectral class. “O” being blue all the way down to “K” being the red.

Pickering: It’s interesting. You took Mina’s original idea of using the letters, rearranged things a little bit, but simplified Antonia Murray’s scheme. How has that changed today, the beginning of the 21st century?

Fleming: We still have the same classification of the stars. We’ve added three more letters at the end and we have found that there are different classifications within the classifications of stars, 1-10, so that we can be more specific in our classification.

Pickering: If you two were alive today at the beginning of the 21st century how do you think your work would be different?

Cannon: I think we would have better equipment and better pay.

Fleming: Definitely better pay. Women back in those days did not get paid as well as men. We got paid half as much as the men would have if they were hired for the Harvard Astronomy Observatory.

Pickering: 25 cents per hour. Are you complaining?

Fleming: Oh, of course not.

Cannon: Secretaries at Harvard were paid more.

Pickering: What about how you were treated. How your peers in the field, scientists – men and women, would have interacted with you different today then back at the time when you were working?

Fleming: I think today no one would question a woman in an observatory. But back then they were prejudice of women working in an observatory.

Cannon: Probably wouldn’t be called the Henry Draper catalogue either since most of the stars classified in that were the ones I classified.

Pickering: This podcast was released April 13, 2009, 68 years to the day after the death of Annie Jump Cannon.

End of podcast:

365 Days of Astronomy
The 365 Days of Astronomy Podcast is produced by the New Media Working Group of the International Year of Astronomy 2009. Audio post-production by Preston Gibson. Bandwidth donated by libsyn.com and wizzard media. Web design by Clockwork Active Media Systems. You may reproduce and distribute this audio for non-commercial purposes. Please consider supporting the podcast with a few dollars (or Euros!). Visit us on the web at 365DaysOfAstronomy.org or email us at info@365DaysOfAstronomy.org. Until tomorrow…goodbye.

About Bruce Palmquist, Feliciti Fredsti, and Marilyn Magenis

Bruce Palmquist is a professor of Science Education and Physics at Central Washington University. He writes a weekly astronomy column for his local newspaper and for the world at http://theellensburgsky@blogspot.com/. Feliciti Fredsti and Marilyn Magenis are physics majors at CWU.

Leave a Reply

Your email address will not be published.

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>

Fill out your info below or Sign-in to post a comment

This site uses Akismet to reduce spam. Learn how your comment data is processed.

One Response to April 13th: Edward, Annie, and Williamina Discuss Spectral Classification

  1. Larry Ovall April 14, 2009 at 12:13 pm #

    I am the Astronomy instructor at Yakima Valley College and I was most impressed with the way you put together this podcast. So great to hear this historical information brought out in an interview format as if talking to the famous lady astronomers themselves. The way you showed their struggles and their brilliant ideas of interpreting stellar spectra was very well done.