Annie Jump Cannon

Yes.

Henrietta Swan Leavitt, Annie Jump Cannon, Sophia Brahe as well, who was told, you may have heard of her brother, Taiko Brahe.

I learned about him in school and his nose.

No.

The strongest were called A stars, the next strongest B, then C, and so on.

But in 1901, a new system was introduced by spectroscopist Annie Jump Cannon, who dropped or merged a few of the old classifications and then rearranged them into one that classified stars by the strengths and appearances of many different absorption lines in their spectra.

A few years later, physicist Max Planck solved a thorny problem in physics, showing how objects like stars give off light of different colors based on their temperature.

Hotter stars put out more light at the blue end of the spectrum, while cooler ones peaked in the red.

The classification scheme proposed by Cannon and decoded by Payne-Gaposchkin is still used today, and arranges stars by their temperature, assigning each a letter.

Because they were rearranged from an older system, the letters aren't alphabetical.

So the hottest are O-type stars, slightly cooler are B, followed by A, F, G, K, and M. It's a little weird, but many people use the mnemonic, oh be a fine guy, kiss me, or oh be a fine girl, kiss me, to remember it, which was dreamed up by Annie Jump Cannon herself.

Each letter grouping is divided into ten subgroups, again according to temperature.

And from that, it helps classify what kind of star it even is.

So for example, while those Harvard computers were doing a bunch of detailed analysis of spectra from all these stars, some of them, including Antonia Mowry and Annie Cannon, came up with very useful classification systems for these stars based on the spectra.

You can then use that classification scheme to tell you which cluster you would expect a given star to fall in in this Hertzsprung-Russell diagram.

For example, whether it should be in this main sequence or if it's something else entirely, like a red giant.

But, you know, we have Cecilia Payne-Gaposchkin, who taught us about the contents of the sun.

Um, and we have Annie Jump Cannon, who classified the stars into a system that we still use now.

Um, and then we have, uh, the duo that gave us the cosmic microwave backro- background radiation, um, and their trials, which incidentally gave me one of my favorite illustrations in the book, which is a pair of very cranky pigeons.

[laughs]

That's a wonderful question.

Of so many moments, I think one moment that exemplifies how, in some ways, I would say bothered Peter can be over the change of the foundation of understanding he has within science, within the hierarchy of the workplace and all of that is when Henrietta is first allowed by Annie Cannon to follow the flaming bush, so to speak, of the Cepheids.

So she notices these Cepheids are pulsing, and she follows that thread to where it leads, and she's making true discoveries.

And I think that it's the moment that he realizes, you know, one particular morning that he realizes that she's really making progress beyond anything he could dream of there.