SGU Episode 331
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Introduction
You're listening to the Skeptics' Guide to the Universe, your escape to reality.
S: Hello and welcome to The Skeptics' Guide to the Universe. Today is November 16, 2011, and this is your host Steven Novella. Joining me this week are Bob Novella,
B: Hey, everybody.
S: Rebecca Watson,
R: Hello, everyone.
S: Jay Novella,
J: Yup-up.
S: and Evan Bernstein.
E: Olas Nuetes. To all of our listeners who speak the Galician language.
J: Or Galactican.
E: Yeah, that's what I thought it looked like, too, Jay, but, in looking at it a little closer, Galician is the language.
S: What is Galician?
E: It has its roots from a Latin-derived language based out of western Spain and Portugal, around the time of the 13th century. And there's currently 3.2 million native speakers in the world, of that language.
S: Um hmm.
E: So it's the Yiddish of Spain, let's call it that.
J?: (In a Yiddish accent) Vat is this, Galician? (laughter)
E: You know, you learn something new every day.
S: That's what you learned today?
E: That's what I learned today. I didn't learn anything else except that.
This Day in Skepticism (01:10)
S: Well, how about November 19th in history?
E: Yes. On November 19th, this day, in history, the Apollo 12 astronauts, Pete Conrad and Alan Bean, land at the Ocean of Storms on the moon, and become the third and fourth humans to walk on the moon.
S: Oceanus Procellarum. Awesome.
E: That is it.
S: Sounds cooler in Latin.
R: It does. I don't know, Ocean of Storms, that's pretty cool, too.
E: Ocean of Storms is pretty cool.
S: Isn't that the next book in the Game of Thrones series?
B: Oh my god, I was thinking the same thing. (laughter)
J: Isn't that, isn’t that also a region on the moon?
S: Yeah.
R: Good one, Jay. (laughter)
E: Love it.
S: It's where they landed.
E: Apollo 12 is the, one of the missions that really gets forgotten about. You know, you have, obviously, Apollo 11, which is the seminal moment.
S: Yeah. 12 is the one after that, right?
E: 12 is, yes. And the one after that is Apollo 13. Of course, you know, the botched mission, with the failure and everything and the very popular, excellent movie, it was based on. But 12 kind of gets lost in the mix.
S: It's the forgotten Apollo mission.
R: (sadly) Oh.
E: It is.
S: You know why, because it was successful! It was the second, so, you know, it wasn't the first, and nothing bad happened. They went to the moon, they completed their mission, they came back.
E: Well, actually something bad sort of did happen. They almost had to abort the mission.
S: Yeah, but almost doesn't count.
R: Horseshoes and hand grenades.
E: But 36-1/2, this is cool . .
B: And Tiddly-Winks.
E: Their end lift-off, 36 seconds into the mission, and lightning becomes discharged through the ship, down through the Saturn V rocket, right down to the Earth. It was, through the ionized plume. And the protective circuits on the fuel cells in the service module falsely detected overloads and took all the fuel cells off-line. They didn't know what to do. They almost had to abort the mission, until Bean remembered seeing this in a simulation about a year ago, that they were practicing for, and they switched something over to auxiliary power, and that corrected the problem. But they, it was really a guess. They weren't sure that that was gonna work. But turns out it did, and off to the moon they went.
S: Awesome.
E: On a less-than-memorable mission, right?
S: That's good work, boys.
E: And something else, one other little interesting factoid. They used Doppler radar in order to land, pretty much precisely on target, where they wanted to, and that was the first time that that had been used by NASA.
S: Yeah, I know Apollo 11 landed way off. So they were testing this new method for precise landing, and it worked well.
E: It did. So, the moon is cool.
News Items
Item 1: The Moon's Magnetic Field (03:55)
S: The moon is cool, and that's why it's our next news item, too. Bob, you're gonna tell us about the moon's magnetic field.
B: Yeah, this is pretty interesting. A forty-year-old moon mystery may have been solved recently. It looks like that we may have two viable theories, not one. We've got two viable theories why some moon rocks that were brought back in the '70s and were examined are magnetized, even though there's no magnetic field around the moon now, and we don't know how there ever could have been, until recently, of course. So, it pretty much started in the '70s, that moon rocks that were brought back from the Apollo missions caused quite a surprise when they examined them and they discovered that they, that they were magnetized. And, this of course meant that there almost certainly had to be some sort of magnetosphere around the moon at some point in its past. I'm not sure why the article I read said "almost" certainly, I mean it seems a hundred percent certain to me. I mean if they're magnetized. . .
S: Well, it's possible that Magneto went back in time to the moon (laughter) and magnetized the rocks where he landed.
E: I knew it, I just knew it.
S: So that's, yeah, you gotta hold out for that, you know.
B: Okay, there's the .000001 percent. The problem, though, is, how did the moon actually make a magnetic field. That's what the big mystery has been for over forty years. The moon is too small to make them, and, at least in the way that the Earth does. So, the Earth's magnetic field is caused by the interplay of two things. You've got the convection of electric charges, which is really key, that's primary. But you've also got rotation, which is also pretty important. This is the essence of a geodynamo. This is exactly what stars do as well. This is how they, how stars create their magnetic fields. The large temperature differences of the liquid metallic alloys in the outer core of the Earth causes like this lava lamp type convection of these electrically conducting fluids. So they, so these fluids move up and down through convection. And this coupled with the rotation of the core is what really creates this magnetic field that extends all the way to the surface and far into space, and which, of course, totally saves our ass,
S: Right.
B: from solar wind, and so it's really nice to have a magnetosphere.
S: And Jupiter has a very strong magnetosphere, and that's because of the metallic hydrogen, right?
B: There you go, the moving charges, yup.
J: Do you guys think with all these fortunate things that made it so life could exist on the Earth
B: Don't go there.
J: Wait. Wait. Do you think, though, that if, say, the moon didn't have a property that protects life, that other life would have evolved?
B: Well, sure. Life that would have been able to evolve in the different environment that whatever the moon lacked, caused.
S: Yeah. Obviously, life adapted to the environment, and so the environment is perfect for whatever life exists, because, you know, life evolved and adapted to it. But, the question is, how far can you stretch that before you're outside the parameters that organic life can form and be stable, and it's hard to say, you know.
R: Like a very wise Ian Malcolm once said, "Life finds a way."
E: Jurassic Park.
R: Yes.
J: So it's possible if the terrain on the Earth and the environment on the Earth was like, totally badass, that some form of life could have evolved that could just withstand extreme temperatures
B: Jay.
S: Like the Horda?
B; Jay, look at. . . Dude, no. (laughter). Not that extreme. But Jay, look at extremophiles. There's bacteria that can survive boiling water. They can survive radiation in space. I mean, sure, it might be so nasty on Earth that all you'd ever really have is these extremophile bacteria, but so, sure.
S: Yeah, but Bob, they . . .
B: That's not a problem at all.
S: wouldn't be extremophiles, they'd be normophiles. (laughter) Because they would be normal and we would be the extremophiles.
J: Well, the cool part about thinking about this, Bob, isn't that it would be bacteria. It'd have to be a complex organism that can think, and all, you know. I'm just thinking of the wicked tough alien that can withstand pretty much anything.
S: Yeah, they would be sitting around wondering if, hey, if the Earth had a magnetic field, do you think life could have evolved and survived? In a constant magnetic field, though, my goodness. Alright, so Bob, so, what's the mechanism, let me get this back on track, what's the mechanism for the moon having a magnetic field?
B: Well, the point is that the moon can't have a magnetic field the way that the Earth does, or stars do. It's way too small. The temperature differences that would be, that are near the core just aren't great enough to support any type of convection that would be required. How did the moon, then, magnetize these rocks? So clearly there's gotta be another way for a geomagnetic field to be created. And this is exactly what these two new theories are dealing with, in the Journal of Nature, I think they're in there now. The first theory describes the moon after it was formed. I think we've talked about this before. In those early years, it was much closer to the Earth. I think it appeared 15 times bigger in the sky. It was much closer.
J: Wow, that's cool.
B: So that, yeah, imagine that night view. So the tidal forces were equally great. They were really titanic. The moon raised mountain-sized tides on the Earth. But that also means that the Earth probably had a pretty dramatic tidal impact on the moon as well.
S: You know what just occurred to me, Bob, when you say that? I don't know if we've talked about this before, but in a lot of science fiction shows, they show these massive moons in the sky, you know, of the planet, and it's beautiful. But there would have to be a titanic. . .
E: Impractical.
S: tidal force, as well.
B: Oh my god, yeah.
S: And they never really show that. You know, they have these planets that are like Earth, but they have these gigantic moons in the sky without accounting for the fact that there would have to be an equally gigantic tidal force.
E: Would multiple moons, how would multiple moons, could one on each side of the planet, sort of equal it out?
S: That would make it worse. If they were on exact opposite sides of the world the tidal forces would actually reinforce each other.
E: Alright, well is there a configuration where if you had multiple moons, it could sort of balance each other out that things would remain stable enough for life to evolve?
B: I don't think it would balance out that way.
S: Yeah.
B: I think you'd end up having, you could end up having four tides a day, type of thing.
S: Yeah.
B: Yeah, or really big ones, or, yeah. It would not be nice.
E: All right.
B: So, Earth's tidal force caused the moon's mantle to actually rotate around a different axis than the molten core was rotating, and this causes turbulence within the molten iron and that gives rise to magnetic fields, which in turn, imprinted itself onto the rocks cooling on the surface of the moon, which are the ones we found. Now, the second theory describes a moon that's being pelted by waves and waves of asteroids, and this gargantuan energy that these asteroids impart on the moon cause the mantle to actually rotate against the rotation of the core, causing turbulence again, which gives rise to the magnetic field. And this turbulence could last for 10,000 years, which would be plenty of time for cooling rock to fossilize the magnetic orientation. So in fact, the period of time in the solar system when this was a common occurrence, it's called the Late Heavy Bombardment, is precisely when the moon's magnetic field seems to have existed. So you've got these two interesting theories, and they are very complementary because they both share this key point that convection is not absolutely required. Simple mechanical stirring is really all you need, it seems, if these theories pan out, to create a magnetic field around a celestial object.
S: Yeah, so essentially the ess…the key component is that the core is rotating at a different angle that the outer mantle, so they're sort of rubbing up against each other causing. . .
B: Yeah. Causing the turbulence, which causes the movement of the electrical charges, and the rotation too, which helps create the magnetic field and there you go.
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