SGU Episode 572

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SGU Episode 572
June 25th 2016
(brief caption for the episode icon)

SGU 571                      SGU 573

Skeptical Rogues
S: Steven Novella

B: Bob Novella

C: Cara Santa Maria

Quote of the Week

The essence of the independent mind lies not in what it thinks, but in how it thinks.

Christopher Hitchens

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Show Notes
Forum Discussion


You're listening to the Skeptics' Guide to the Universe, your escape to reality.

S: Hello, and welcome to The Skeptic's Guide to the Universe. Today is Monday, June 20th, 2016; and this is your host, Steven Novella. Joining me this week are Bob Novella,

Forgotten Superheroes of Science (0:54)[edit]

Mary Edwards

S: Bob, why don't you start us off with Forgotten Superheroes of Science.

B: Sure. This week, for Forgotten Superheroes of Science, I'll be talking about Mary Edwards, 1750 to 1850. She was among the very few women in the late 1700's to actually earn a living from scientific work. Edwards' husband, John, had taken on some work from the British Nautical Almanac for extra money for his family.

His job, among thirty four other all-male human computers (as you know, back in years ago, a computer was actually a person who was doing computing), their job was to study the Moon and the Sun and the planets at various times of the day, and notice accurately as possible their positions in the sky. Now these nautical almanacs were created every year, and they were used for (obviously) navigation at sea. And he did this from 1773 to 1784 – the year he died.

Now Mary Edwards then wrote to the Almanac people asking if she could continue the work to help support her family, 'cause, as it turns out, after her husband's death, they lost the house that they lived in, they lost pretty much everything. The only thing the family got was debt, this massive debt. She was in dire straits. She asked if she could continue the work that he was doing.

And at least according to some sources, the claim is that she actually did most of the calculations for her husband for all those years. It was really her that was doing ...

S: 'Cause she was doing it anyway!

B: Yeah, she was doing it anyway! So I think – it was hard to get a sense if they believed her or not. I mean, remember, we're talking the late 1700's here. But I think after taking on the work, it became kind of obvious. Over the years, she became known for her skill and her accuracy, and she actually took on double the work that her husband did, 'cause this was really her main job, whereas he was doing this just for extra work.

And I think she actually took on so much work that some times she was doing half the almanac herself. So she was doing a ton of work. And she was so good and so successful, and it was able to take on even extra work, that after six or seven years, she actually paid off all of her debt. So it went incredibly well for her.

She also, she trained her daughter as well, and together, these two Edwards women performed this vital role for like, fifty-five years. They made these vital contributions to this almanac. So remember Mary Edwards. Mention her to your friends, perhaps when discussing the obliquity of the ecliptic, or perhaps, ecliptic rectangular geocentric coordinates.

S: Got that on the first try.

B: Yes!

C: Yeah, nice!

(Bob laughs) (Cara laughs)

S: Good job.

News Items[edit]

Electric Plane (3:29)[edit]

Naturopathic Licensure (12:44)[edit]

Black Holes and Dark Matter (23:11)[edit]

(Commercial at 33:55)

What's the Word (35:20)[edit]

  • Crepuscular

S: All right, Cara, What's the Word this week?

C: The word this week is a fun one to say, and it was recommended by Blithe Nilson from British Columbia. He says one of his favorite words is: Crepuscular. I love that word too.


S: It doesn't sound like what it is though, but it is a cool word.

C: It does not. It sounds like some sort of disease state, or

S: Yeah

C: something you pop.

S: Some kind of rash.

C: Yes.

S: You have a very crepuscular rash.

C: Yes! Yes, something with boils.

B: I think it sounds exactly ...

C: Really!

B: Yes, I don't know.

C: I wonder if you came across the term crepuscular early on when you were reading, because I think sometimes the earlier that words make their way into your consciousness, the more

S: Oh yeah

C: they truly carry that weight. So, if you don't know what crepuscular means, 'cause you've always thought it was some sort of hideous rash, its definition is straightforward: “Of, relating to, or resembling twilight.” And specifically, we use it more in science as referring to animals, or insects, organisms that are active during twilight, or things that occur during twilight.

So, even though you can use it in general, in a literary sense, to relate to twilight, if you're writing poetry, there could be a crepuscular feeling in the air. We saw a resurgence of this use more recently in the scientific literature. The figurative use did start way back in the 1660's. And around 1755, we started to see the use in the scientific literature.

And it comes from, basically, an early Roman term that was used for twilight. It was “creper,” which meant “dusky.” And so “crepusculum” was the way that Roman writers would refer to the half-light of the evening. So they were talking about right after the sun sets, it's the crepusculum portion of the evening. And then, when, right before the morning comes up, which is also a type of twilight, that was the diliculum portion of the evening. And diliculum completely died off. Like, we don't use that at all. But crepuscular did make its way back into the lexicon.

So, certain things that are crepuscular would include fire flies (which are actually beetles, not flies), moths, cats, and even rabbits, and also, remember that there are some terms of crepuscular that don't relate to animals. For example, crepuscular rays are – you know how you look up, and I always refer to it as a Jesus postcard. I'm like, “Wow! The sky really looks

B: Yes!

C: like a Jesus postcard.” But the sun is setting. It's twilight. And basically, the rays of the sun stand out against the unlit air around them. Those are referred to as crepuscular rays, when you can really see those sun rays. It's a great word.

B: Yeah, it is. And when I think of “crepuscular,” that's what I think of. I don't think of anything else, except

C: Yeah

B: crepuscular rays. And yeah, they seem to radiate from a point. And, yeah, it's just a perspective thing, like railroad tracks. And there's also, the opposite of that is the anti-crepuscular rays, where they seem to converge on a point. And that point is always opposite to the sun.

C: Yeah

B: And that's caused by the same thing. It's a perspective thing. And they're beautiful.

C: Yeah

S: So, yeah, you have nocturnal – everyone knows that term, right? You mentioned diurnal, which is

C: Diurnal, yep

S: Crepuscular is twilight. What's – metudinal, did you say that one?

C: I didn't say metudinal. I didn't add metudinal.

S: Metudinal means getting up right before dawn.

C: Yeah, that's the other type of twilight.

S: Yeah. And vespertine.

C: Vespertine?

B: Whoa!

S: In the evening, so like, right after

C: Ah!

S: sunset. So, yeah, so these are just all different, specialized, mainly to refer to when animals are active.

C: I think I'm quite crepuscular.

S: You think so?

C: I think so. I'm quite active at twilight.

S: I'm metudinal, myself.

C: Hm! I'm absolutely not metudinal. I am dead asleep during that portion.

S: Nah, I love waking up right before sunrise.

C: Oof!

B: What!

C: That sounds like my worst nightmare.

S: Oh yeah.

B: Oh my gosh!

(Cara chuckles)

Interview with Michael Marshall (39:24)[edit]

S: Well, guys, let's go on with our interview. And for those of you who are Premium members of the SGU, I will be simultaneously making available the uncut version of this interview, which is over forty minutes long. So take a look for that in our premium content.

(Commercial at 1:02:23)

Science or Fiction (1:03:40)[edit]

(Science or Fiction music)
It's time for Science or Fiction

Skeptical Quote of the Week (1:17:37)[edit]

S: And until next week, this is your Skeptic's Guide to the Universe.

S: The Skeptics' Guide to the Universe is produced by SGU Productions, dedicated to promoting science and critical thinking. For more information on this and other episodes, please visit our website at, where you will find the show notes as well as links to our blogs, videos, online forum, and other content. You can send us feedback or questions to Also, please consider supporting the SGU by visiting the store page on our website, where you will find merchandise, premium content, and subscription information. Our listeners are what make SGU possible.

Today I Learned:[edit]

  • This is a very rare episode with just Steve, Bob, and Cara


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