Tag: Cathleen

Planetary Chemistry

On By rolcottIn Astronomy: Planetary Science, Chemistry, UncategorizedLeave a comment

The deal’s gone round to Susan. “Another thing, Kareem — your assumption ignores Chemistry.”

“Didn’t Cathleen take care of that with her nuclear reactions in the star’s core?”

“Not even close. Nuclear reactions in general are literally a million or more times more energetic than chemical ones. Your classic AA alkaline battery is 1½ volts, right, but the initial step in Cathleen’s proton‑to‑helium process would net 1½ megavolts if we could set it up in a battery. Regular chemistry just re‑arranges atoms, doesn’t have a chance when nuclear’s going on.”

“Like trying to carve a cameo with dynamite, huh?”

“Not quite. If nuclear is dynamite, then bench chemistry is a bandsaw. I’d say the analog for carving a cameo would be cell biology. That operates at the millivolt level.”

Cathleen holds up her tablet again. “Speaking of abundance graphs, here’s another one I built for my Astronomy class. I divided each element’s atom count in Earth’s crust by its atom count in the Universe. I color-coded the points according to Goldschmidt’s classification scheme. The lines mark the average ratio for each class. Compared to the Universe, oxide‑formers are ten times more concentrated in the crust than sulfide‑formers are, 150 times more concentrated than iron‑mixers, 900 times more than gases. I see the numbers but I don’t feel comfortable with them. Kareem, what do I tell my students?”

“Happy to explain the what, but Susan will have to explain the why. Goldschmidt started as a mineralogist, invented Geochemistry while bouncing around between Sweden, Norway and Germany until he barely escaped from the Nazis and was smuggled into England. He pioneered using crystallographic and thermodynamic analysis in geology. His scheme slotted each chemical element into one of those five classes. For example, he lumped the five lightest inert gases together with hydrogen, nitrogen and carbon into what he called the Atmophile class because they mostly stay in the atmosphere.”

“Carbon?”

“Yeah, that one’s iffy because coal and limestone. His reasoning involved carbon monoxide, carbon dioxide and methane which don’t show up in rocks. There are other edge cases, like radon which ought to count as a gas but shows up in rocks and basements because it’s locked where it was generated as part of uranium’s decay sequence. We mostly find uranium in oxide minerals so Goldschmidt put it and radon into his Lithophile class of metals that occur in oxides. That’s opposed to mercury, silver and a dozen or so other elements that generally show up in sulfide minerals — that’s his Chalcophile class. There’s another dozen or so that dissolve into molten iron so they’re Siderophiles. We don’t see much of those in Earth’s crust because they were swept down to the core as the molten planet differentiated. Finally, there’s a whole batch of radioactives that huddle together as Other. But why those elements do those things, I dunno. Susan, your turn.”

“It’s a lovely application of Pearson’s Hard‑Soft Acid‑Base theory. Hard chemical thingies have a high charge‑to‑volume ratio. Also, their charge is tightly bound so it doesn’t polarize. Oxide, carbonate and fluoride ions are Hard, and so are alkali and alkali metal ions like sodium and calcium. Uranium’s Hard when it’s at high oxidation state like in a uranyl ion UO22+. (Eddie, stop snickering, that’s its proper name.) Soft thingies are just the reverse — big thingies with mushy electron clouds. Iodide is Soft and so are mercury, silver and gold ions. Bulk metals are extremely Soft, chemically speaking, because their electron clouds are so diffuse. The point is, Hard thingies combine best with Hard thingies, Soft thingies with Soft.”

“So the Lithophiles are Hard metals that make Hard‑Hard stony oxides. I suppose that extends to fluorides and carbonates?”

“Sure.”

“Then the sulfide ores, Goldschmidt’s Chalcogens, are Soft‑Soft compounds. The Siderophile metals combine with each other better than anyone else, and the Atmophiles don’t combine with anything. Cool.”

“Ah‑HAH! Then on my graph the Hard oxides are most common in the crust because they’re light and so float above the heavier Soft sulfides and the ultra‑Soft metals that sink to the core. Our planet is layered by Hardness.”

“Does the same logic apply to asteroids?”

“Sort of.”

~~ Rich Olcott

The Road to Gold

On By rolcottIn Astronomy: Stellar Science, UncategorizedLeave a comment

Cathleen and Susan share a look.
 ”A conclusion way too far, Kareem.”
  ”Yep, you’ve overbounded your steps.”

Kareem tosses in a couple of chips. “Huh? What did I skip over? Where?”

Cathleen sees his bet and raises. “When you said that the Psyche asteroid’s gold content would be similar to what we dig up on Earth, you skipped many orders of magnitude in applying the Cosmological Principle.”

“I didn’t realize I’d done that. What’s the Cosmological Principle?”

“There’s several ways to state it, but they boil down to, ‘We’re not special in the Universe.‘ We think that fundamental constants and physical laws determined here on Earth have the same values and work the same way everywhere. Astrophysics just wouldn’t work as well as it does if the electron charge or Newton’s Laws of Motion were different a million lightyears away from us.”

“Wait, what about that galaxy that’s going to collide with us even though everything’s supposed to be flying away?”

“Fair question. The un‑boiled Principle includes some qualification clauses, especially the one that says, ‘when averaged over a large enough volume.’ How big a volume depends on what you’re studying. For motions of galaxies and such you have to average over a couple hundred million lightyears. Physical constants measured locally seem to be good out to the edge of the Observable Universe. Elemental abundances are somewhere in‑between — the very oldest, farthest‑away galaxies have less of the heavy stuff than we do around here. <pulls her tablet from her purse> Which brings me to this chart I built for one of my classes.”

“You’re going to have to explain that.”

“Sure. Both graphs are about element abundance. We get the numbers from stellar and galactic spectra so we’re averaging the local Universe out to a few hundred thousand lightyears. Left‑to‑right we’ve got hydrogen, helium, lithium and so on out to uranium in the big graph, out to iron in the small one. Up‑and‑down we’ve got atom count for each element, divided by the number of iron atoms so iron scores at 1.0. The range is huge, 31 000 hydrogens per single iron atom, all the way down to 17 rhenium atoms per billion irons. I needed this logarithmic scale to make the points I wanted to make in class.”

Vinnie sweetens the pot. “You’ve got that nice zig‑zag going in the little graph, Cathleen, but things get weird around iron and the big graph has that near‑constant series starting around 60. Why the differences?”

<lays down Q‑J‑10‑9‑8, all hearts, pulls in the chips> “Perfect straight line, Vinnie. The different behaviors come from nuclear cookery at different stages of a star’s life. Most new‑born stars start by fusing hydrogen nuclei, protons, to produce helium nuclei, alpha particles. Those two swamp everything else. As the star evolves to higher temperatures, proton‑addition processes generate successively more massive nuclei. Carbon starts a new pattern, because alpha‑addition processes it initiates generate the sawtooth pattern you picked up on — an alpha has two protons so each alpha fusion contributes to the atomic number peak two units along the line.”

“What happens with iron?”

“What happens when you put a blow torch to a red‑hot metal ball?”

“The ball melts.”

“Why?”

“Cause the extra energy’s too much for what holds the ball together.”

“Well, there you go. The forces that hold an atomic nucleus together have their limits, too. Iron and its next‑but‑one neighbor nickel are right on the edge of stability for alpha reactions. The alpha process in the core of a normal star can’t make anything heavier.”

“So how do we get the heavy guys?”

“Novas, supernovas and beyond. Those events are so energetic and so chaotic there’s non‑zero probability for any kind of atom to form and evolve to something stable before it can break down. Massive atoms just have a lower probability so there’s less of them when things settle down. Gold, for instance, at only 330 atoms per billion atoms of iron. The explosions spray heavy atoms throughout their neighborhood.”

Kareem antes the next pot. “So you’re saying my mistake was to assume that asteroid Psyche’s composition would match whole‑Universe heavy‑element statistics?”

“Well, that was his first mistake, right, Susan?”

~~ Rich Olcott

The Name’s Not The Same

On By rolcottIn General: Fun Stuff, UncategorizedLeave a comment

The regular Thursday night meeting of the Acme Pizza and Science Society around the big circular table at Pizza Eddie’s. Al comes in, hair afire and ready to bite the heads off tenpenny nails. “This is the last straw!” <flings down yet another astronomy magazine>. “Look at this!”

I pick up the issue. “Looks like the lead article’s about the Psyche mission to the Psyche asteroid. You got a problem with that?”

“Nah, that’s just fine, exciting even. Look at the address label.”

“Ah, I see your objection. Instead of your first name it says ‘A. I.’ like those are your initials. Are they?”

“No. Never had a middle initial until the Navy gave me ‘N‘ for ‘No middle initial‘ and I dropped that soon as I got out.”

“So where’d they get the ‘I’?”

“That’s what chafes my cheeks, Vinnie, people messing with my name. All this stuff going on these days about Artificial Intelligence which everybody calls ‘AI’ which looks too flippin’ much like Al. People have been ribbing me about it since ChatGPT hit the street. They come in here asking me for virtual coffee or wanting to know about my ALgorithms. One guy claimed I parked a driverless coffee machine back of the kitchen. But it’s not just jokes. I get calls asking for programming help with languages I never heard of. My checks have my name as Al but the bank lady gives me grief because I don’t sign them with A. I.”

“You’ve got a good point there. When someone chooses a name, that name’s important to them. I know whole families where everyone has a ‘go‑by‘ name. First class I ever taught, I opened by calling the role so I could tie names to faces. I started out calling out first names but quickly learned that most of the men and half the women went by middle names — this was in the South where that’s common but still. Anyway, I called first and middle names until I got to this one kid. He’d gone through three years of college going by ‘C-M’ until I blew his cover by asking which student was named Clyde and it was him. I don’t think he ever forgave me.”

“I know the feeling, Cathleen. None of the teachers could handle my full name. This magazine’s stupid spell‑checker musta corrected me wrong. I want a new name that doesn’t get messed up.”

“Al’s not your full name?”

“No, it’s Aloysius which I don’t like. No-one can spell it, or say it right if they see it written out. I got named after my Mom’s favorite uncle before I could vote against it. I’ve been going by Al ever since I knew better.”

“We need to figure you a new name that looks different but sounds almost the same so you’ll recognize it when we holler at you, right?”

“That’s about it, Vinnie. Whaddaya got?”

“A negative to begin with. We can rule out Hal, the killer computer in the 2001 movie. Don’t want to see our physicist here walk up for a strawberry scone and get ‘I’m afraid I can’t do that, Sy.’ Haw!”

“How about Sal?”

Eddie waves it away. “My Uncle Salvatore’s already got that. One’s enough.”

I read off Old Reliable’s screen. “Baal was a god worshipped by some of the Old Testament enemy tribes, eventually turned into Beelzebub. That won’t do. And ‘mal‘ means ‘bad‘ in Spanish.”

Resident chemist Susan giggles. “I don’t suppose you’d be happy if I greeted you with a cheery, ‘Hey, Gal‘. Oh, wait, I’ve got a Chemistry thing for us. ‘Cal‘ is the standard abbreviation for ‘calorie,’ one of the old‑time measures of heat energy before everybody settled on the joule. What do you think of ‘Cal‘? Hot and cool and rugged enough for you?”

“Hmm… I like it. ‘Cal’s Coffee‘ even has that market‑winner k’‑kuh sound like Krispy Kreme and Captain Crunch and Crispy Critters. It’s official — from now on, Cal is my official go‑by name. Thanks, Susan.”

She grins. “First time I’ve named an adult. Hi, Cal.”
 ”Hi, Cal.”
  ”Hi, Cal.”
   ”Hi, Cal. Now about that magazine article…”

Adapted from a photo by Edward Eyer

~~ Rich Olcott

Eclipse Correction

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

From: Robin Feder <rjfeder@fortleenj.com>
To: Sy Moire <sy@moirestudies.com>
Subj: Bad diagram

My Dad said I should write you about the bad video that is in your “Elliptically Speaking” post. It shows a circle around a blue dot that’s supposed to be the Earth, and an oval shape that’s supposed to be the Moon’s orbit around the Earth, and blinking thingies that are supposed to show what eclipses look like. I took a screen shot of the video to show you. But the diagram is all wrong because it has two places where the Moon is far away from the Earth and two places where the Moon is closer and that’s wrong. All the orbit pictures I can find in my class books show there’s only one of each. Please fix this. Sincerely, Robin Feder

From: Sy Moire <sy@moirestudies.com>
To: Robin Feder <rjfeder@fortleenj.com>
Subj: Bad Diagram

You’re absolutely correct. That’s a terrible graphic and I’ll have to apologize to Cathleen, Teena and all my readers. Thanks for drawing my attention to my mistake. When I built that animation I was thinking too much about squashed circles and not enough about orbits. I’ve revised the animation, moving the Earth and its circle sideways a bit. Strictly speaking, Earth and the Moon both orbit around their common center of gravity. Also, the COG should be at one focus of an ellipse. An ellipse has two foci located on either side of the figure’s center. However, both of those corrections for the Earth‑Moon system are so small at this scale that you wouldn’t be able to see them. I drew my oval (not a true ellipse) out of scale to make the effect more visible.

Moving the oval so that there’s only one close place and one far place (astronomers call them perigee and apogee) meant that I also had to move the blinking eclipse markers. I think the new locations do a better job of showing why we have both annular and total eclipses. You just have to imagine the Sun being beyond the Moon in each special location so that the eclipse shadow meets the Earth.

I’ve swapped out the bad diagram on the website. Here’s a screenshot of the better diagram I’ve put in its place.

Please remember to use proper eclipse-viewing eyewear when you look at this October’s annular eclipse. And give my regards to your Dad.

~~ Rich Olcott

  • Thanks to Ric Werme for gently pointing out my bogus graphic.

Elliptically Speaking

On By rolcottIn Astronomy: Planetary Science, Uncategorized2 Comments

“Oh. I have one other eclipse question, Dr O’Brien.”

“What’s that, Teena?”

“Well, I found a list of solar eclipses—”

“An interesting place to start, especially for a 10‑year‑old.”

“And it had three kinds of eclipse — total, partial and annual. ‘Total‘ must be when the Moon covers up the whole Sun like when I wink my eye tight. ‘Partial‘ sounds like when I only squinch up my eye like this. I guess that happens when we’re just on the edge of an eclipse track so we still see part of the Sun like we see just part of the Moon most of the time. But my eye wide open is like there’s no eclipse at all. There’s no fourth way to hold my eye left over for ‘annual.’ Besides, ‘annual‘ means ‘every year.’ Is there some special kind of eclipse that comes every year but we don’t see it?”

Cathleen doesn’t quite hide a smile. “Sorry, dear, I think you’ve misread a word. It’s not ‘annual,’ it’s ‘annular.’ They’re very similar and they both came from Latin but they came from different Latin words and have different meanings today. ‘Annual‘ means ‘yearly,’ just as you said. ‘Annular‘ means ‘ring‑shaped‘, like a circle with a hole in the middle.”

“A ring‑shaped eclipse? Is there a big hole in the Moon we only see sometimes?”

“Quite the reverse. The Moon and its shadow are compact, no holes even in an annular eclipse. What we see in those eclipses is a ring of the Sun’s light around the outside of a black disk of Moon‑shadow. The bright ring is called an ‘annulus‘ and you must be very careful to use the special dark glasses to look at it.”

“But … Uncle Sy said the reason we’re so lucky we can see eclipses is that the Moon is just the right size to match the size of the Sun. Does the Moon get smaller for an annular eclipse?”

“Hold up your thumb. Now move your arm out until your thumb just covers my head. Can’t see me at all, can you? Now move your arm out just a little farther until you can see my hair but not my face. Got it? Your thumb didn’t change size, did it?”

“No, it just looked smaller and I could see more of you past it.”

“Right. That’s how an annular eclipse works.”

<drawing Old Reliable from its holster> “Excuse me, Cathleen, I think this might help.”

“What are all those circles, Uncle Sy, and why does it blink?”

“It’s like a map of space. The blue disk represents Earth and the gray disk represents the Moon. If the Moon were always the same distance from Earth it’d follow the black circle, but it doesn’t. It follows the red line which isn’t a true circle. It’s a special shape of squashed circle, called an ellipse. Very few moons or planets follow a truly circular orbit — their track is almost always elliptical to some degree. Now you tell me what the blinky things are about and don’t say it’s when the Moon stops in its orbit because it doesn’t. The animation motion pauses to call attention to when the eclipses happen.”

“Okayyy… Oh! They’re what we’d see in an eclipse, right? The red … ellipse?… brings the Moon closer to us or farther away. When it’s close like over there it’s like my thumb covering Dr O’Brien’s whole head and we don’t see any of the Sun and that’s a total eclipse, right? When we have an eclipse if the Moon’s outside of that circle like on the side, it’s like my thumb farther away and that’s why your picture has the orange ring, it’s an annulus, right?”

“You broke the code, Teena, Well done!”

“I think it’s silly to have two words like eclipse and ellipse that sound so much alike but they’re so different. Like annual and annulus.”

“Sorry about that, sweetie, but we pretty much have to take the language as we find it. English has a long and complicated history. Sometimes I’m surprised it works at all. Sometimes it doesn’t and that makes problems.”

~~ Rich Olcott

Eclipse Vectors

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

“I think I understand why we have eclipse seasons, Dr O’Meara, but why do the two eclipses in a season travel in such different directions?”

Image from GreatAmericanEclipse.com

“Put this question on top of Teena’s, Cathleen. Everyone knows the Sun rises in the East because the Earth rotates towards the East. But it seems like eclipses fly eastward even faster than the Earth turns. If that’s true, why?”

“As an Astronomy educator, Sy, I wish ‘everyone’ were truly everyone. You wouldn’t believe the arguments I get from some students when I’m trying to teach 21st Century material. Why are they even in my class?”

“We can only wonder. You and the Flatties, Kareem and the 6000‑year Earthers, poor Jennifer over in Public Health having to cope with the anti‑vaxxers; these contrarians seem to be everywhere. They’re excellent models of Orwellian doublethink — they happily use their science‑dependent smart phones, internet and GPS while they’re trashing Science. Split brains? I dunno.”

“C’mon, Uncle Sy, that’s boring grown‑up stuff. What about my eclipses? Why do they go north or south like that? Does it have to do with those angles that were drawn too big?”

“Sorry, sweetie. Dr O’Meara showed us that the Moon can only make an eclipse if it’s near the Solar System’s plane where Earth’s center stays. The angle of the Moon’s orbital plane only matters when the Moon is away from there.”

“Earth’s center is the Equator! All the eclipses should go on the Equator. But they don’t. That’s wrong.”

“The Equator’s around Earth’s center, Teena, but so are other circles. Think of your globe at home. Does the North Pole point straight up?”

“Noo‑oh … you mean the tilt? Mom said that was about Winter and Summer.”

“Well, she’s not wrong. In the northern hemisphere we have Summer when the North Pole tilts toward the Sun, Winter when it tilts away. That’s only part of the story, though. In Spring and Fall the tilt is broadside to the Sun. Not as hot as Summertime, not as cold as Winter. Those three gyroscopes give us eclipse seasons. But they do more. Look at these diagrams.”

“Sorry, I don’t understand what you’re showing me.”

“No worries. In the upper one, the Earth’s in the rear. The North Pole is the green arrow. The Equator’s the yellow band. Pole and Equator are both tilted 23°. The Sun is in front, shining at the Earth. The Earth orbits the Sun counterclockwise so it’s moving to our left. Moving in that direction gives the northern hemisphere more and more daylight so it’s northern Springtime going towards Summer. Okay?”

“Yyyes….”

“Good. The sketch shows eclipse conditions, when the Moon and its shadow are in Earth’s orbital plane. The only places on Earth that can see the eclipse are on the red band. That’s another circle where the plane intersects the Earth’s surface. What direction does that band point on Earth?”

<chortle> “It goes northeast, just like I noticed on that map! Okay, let me think about the other picture… The North Pole’s a gyroscope and doesn’t change direction so we’re looking at us from the other side … Yeah! That red band goes southeast on Earth. Perfect! … Umm, everything’s upside‑down for Bindi in Australia, so does she … Wait, in the upper picture when it’s Springtime for us it’s Autumn for her so her Autumn eclipses go northeast, just like our Springtime ones do! And her Spring’s the bottom picture and her Springtime eclipses go southeast like our Autumn ones, right?”

Image from GreatAmericanEclipse.com

“Smart girl! I’m going to tell your Mom about your thinking and she’ll be so proud of you. Now, Cathleen, how about speedy eclipses going east faster than the Earth does?”

“It’s not the eclipse going fast, Sy, it’s the Moon. Relative to the Sun‑Earth line, the Moon in its orbit is traveling eastward at just under 3700 kilometers per hour. Meanwhile, a point on Earth’s Equator is heading in the same direction at just under 1700 kph. Places away from the Equator move even slower. The Moon and its shadow win the race going away.”

~~ Rich Olcott

  • Thanks again to Naomi Pequette for her expertise and eclipse‑related internet links.

Eclipse Seasons

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

“C’mon in, Sy.”

“Morning, Cathleen. You know my niece Teena.”

“Hi, Teena. What brings you here to my office?”

“I’m working on a school project about eclipses, Dr O’Meara, and I noticed something weird. Uncle Sy said you could explain it to me. You know how an eclipse isn’t in just one place, the Moon writes its shadow along a track?”

Image from GreatAmericanEclipse.com

“Of course, dear, I do teach Astronomy.”

“Sorry, I was just giving context.” <Cathleen and I give each other a look.> “Anyhow, I found this picture of lots of eclipse tracks and see how they weave together almost like cloth?”

“Oh, it’s better than that, Teena. Look at the dates. Is there a pattern there, too?”

“Oooh, the Springtime ones go northeast and the Fall ones go southeast. Hey, I don’t see any in the Summer or Winter! Why is that?”

“It’s complicated, because it’s the result of several kinds of motion all going on at once. Have you ever played with a gyroscope?”

“Uh-huh, Uncle Sy gave me one for my birthday last year. He said that 10 years was old enough I could make it spin without hitting someone’s eye with the string. He was mostly right and I promise I really wasn’t aiming at Brian.”

<another look> “Well … okay. What’s a gyroscope’s special thing?”

“Once you start it spinning it tries to stay pointing in the same direction, except mine acts dizzy a little. Uncle Sy says the really good ones they put in satellites don’t get hardly get dizzy at all.”

“Good, you know gyroscope behavior. Planets spin, too, though a lot slower than your gyroscope. Do you know about planets?”

“Oh yes, when I was small and we looked at the eclipse my Mom and Uncle Sy explained about how we live on a planet that goes round the Sun and sometimes the Moon gets in the way and makes a shadow on us but when the Earth turns so we’re facing away from the Sun we’re in Earth’s shadow.”

“Nice. Well, here’s a diagram about how eclipses happen. It shows four Earth‑images at special points in its orbit. Each Earth has Moon‑images at two special points in the Moon’s orbit. There’s also an arrow coming out of each Earth’s North Pole to show the axis that the Earth spins on. We’ve got three circular motions and each one acts like your gyroscope.”

Adapted from a graphic by Nela, licensed under CCA-SA 4.0

“Does the Moon spin, too?”

“We talked about this a couple years ago, sweetie. The Moon always keeps one face towards the Earth so it spins once each month as it orbits around the Earth. Dr O’Meara’s just using a single circle to cover both, okay?”

“Okay. So there’s three gyroscopes, four really but one’s hiding. The picture says that all three point in different directions, right, and they stay that way?”

“Perfect.”

“Excuse me, but those angles don’t look right. The Earth axis is pointed too close or something.”

“Sharp, Sy. You’re partially correct. Actually, that axis is at a proper 23° angle from the perpendicular to Earth’s orbital plane. It’s the lunar orbital plane and its axis that are off. They’re supposed to be at a 5° angle to Earth’s plane but they’re drawn at 15° to highlight that important line where the two planes meet. The gyroscopes keep that line steady all year.”

“What’s so important about the line?”

“If the Moon is too far above or below Earth’s plane, its shadow is too far above or below Earth to make an eclipse. Eclipses only happen when the line runs through the Sun AND when the Moon is close to the line. The line only runs through the Sun in the Spring and Fall, in this century anyway, so those are our eclipse seasons.”

“Why not every century?”

“A century ago, the eclipses came a few months earlier. The gyroscopes slowly drag the line around Earth’s solar orbit, shifting when the eclipse seasons arrive. If you want a New Year eclipse you’ll have to wait a long, long time.”

~~ Rich Olcott

  • Thanks to Naomi Pequette, Peak Nova Solutions, whose “Eclipses” presentation inspired this post.

Big Spin May Make Littler Spins

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

“Sorry, Vinnie, if there’s anything to your ‘Big Skip‘ idea you can’t blame Jupiter’s Great Red Spot on Io.”

“Come again, Cathleen? Both you and Sy were acting intrigued.”

“That was before I looked up a few numbers. You suggested that a long‑ago grazing collision between Io and Jupiter could account for Jupiter’s weird off‑center magnetic field, its Great Red Spot and Io’s heat and paltry waterless atmosphere. The problem is, there’s two big pieces of evidence against you. The first is Io’s orbit. It’s almost a perfect circle, eccentricity 0.0041, less than half the average of the other Galilean moons. A true circle has zero eccentricity compared to a parabola at 1.0.”

“So why is that evidence against the idea?”

“There’s virtually zero probability that a chaotic skip would send Io directly into such a perfect orbit. Okay, repetitive tugs from Ganymede’s and Europa’s gravity fields could conceivably have acted together to circularize and synchronize Io’s behavior but that would take millions of years.”

“So it’d take a while. Who’s in a hurry?”

“Your idea is, because of the second piece of evidence. Jupiter is a fluid planet, gaseous‑fluid much of the way in, liquid‑fluid most of the rest, right? Lots of up‑and‑down circulation due to outward heat flow from Jupiter’s core, plus twisty Coriolis winds at all levels powered by the planet’s rotation. All that commotion would smear out any trace of your grazing collision, probably within a hundred thousand years. The scars from Shoemaker-Levy’s impact on Jupiter were gone within months. Circularization’s too slow, smearing’s too fast, idea’s pfft.”

“Oh well, another beautiful picture bites the dust.” Vinnie glances up and to the left, the thing he does when he’s visualizing stuff. (On him, a quick glance up and to the right is a bluff tell but he knows I know which makes things interesting.) “Okay, so we’re thinking about how Jupiter’s weird atmosphere and how its equator rotates faster than its poles. That cylinder spinning inside a spinning cylinder idea looks nice for an explanation but I can think of a different way it could happen. How about like a roller bearing?”

“Hmm?”

“Big spinning columns deep inside all around the planet. Think about what goes on in between those cylinders you talked about — two layers flowing at different speeds right next to each other. There’s gonna be all kinds of watchacallit – turbulence – in there, trying to match things up but it can’t. Sooner or later twisters are gonna grow up to be north‑south columns.”

“He’s got a point, Cathleen. His columns would reduce between‑layer friction at the cost of increased between‑column friction. Depending on conditions that could give a lower‑energy, more stable configuration.”

“Spoken like a true physicist, Sy. Columns may be part of the story, but not all of it. There’s mostly‑for evidence but also really‑against evidence.”

Adapted from images by NASA/JPL-Caltech/SwRI/ASI/INAF/JIRAM

“Give us the ‘mostly‑for,’ make us feel good.”

“You guys.” <drawing tablet from her purse, tapping screen> “Alright, here’s a couple of images that Juno sent us when it orbited over Jupiter’s poles.”

“Sure looks like what was in my mind. I’ve seen that before somewhere…. Yeah, Al had that poster up behind his cash register like five years ago.”

“Impressive memory, Vinnie. Anyway, those vortices are similar to your idea, except look at these images critically.”

“Wait, different whirlpool counts top and bottom.”

“Right. These columns obviously don’t go all the way through. They must extend only partway inward until they’re blocked at some lower level.”

“Why can’t I have my columns all the way through if they’re outside the blocking level?”

“You could and there may be something like that inside the Sun, but that’s probably not the case for Jupiter.”

“Why not?”

“That’s the ‘really‑against’ evidence — the Great Red Spot and Jupiter’s off‑center magnetism. Something’s powerful enough to cause those two massive phenomena. That something would disrupt your ring‑in‑a‑ring rotation, at least down to the level where the disrupter lives. Your columns could only operate in some layer deeper than the disrupter’s level but above whatever’s blocking the polar columns. If there is such a layer.”

“Geez. Well, a guy can still hope.”

“But that’s not Science.”

~~ Rich Olcott

The Big Skip?

On By rolcottIn Astronomy: Planetary Science, UncategorizedLeave a comment

Suddenly Vinnie gets a grin all over his face. “Tell me something, Cathleen. Suppose I’m a pilot in a shuttle craft like in Star Trek. Tell me how conditions change as I dive down into Jupiter.”

“Hmm .. okay. Mind you, it’ll be a dangerous flight. You’ll fly through an atmosphere that’s mostly molecular hydrogen which is notorious for sneaking into metallic materials and weakening them. I recommend investing in a Starfleet‑grade force shield to keep the atmosphere completely away from your hull. While you’re in the stratosphere high above the cloud decks you’ll see a deep blue sky pretty much the same as Earth’s stratosphere. Try to avoid the thin gray clouds in the upper troposphere — their greasy hydrocarbons will fog your windshield. You want to stick to clear air as much as possible so dodge around the white ammonia‑ice zones. You can drop a couple hundred kilometers more before you hit the top of a brownish ammonium sulfides band.”

“Once I’m that deep there’s clear air underneath the white deck, right?”

“We just don’t know. Unlikely, but if you do want to fly beneath a zone you’ll have to traverse the jetstream separating it from your band. Pick the pole‑ward zone — jetstreams on that side seem to host fewer thunderstorms. Strap in for the jump, because the jetstreams sustain windspeeds 2‑3 times what we get in a Category 5 hurricane. Things’ll get muddier when you drop beneath the brown clouds.”

“Brown as mud, uh-huh.”

“No, I mean literal mud, maybe. First there’s a water‑ice layer and below that there may be a layer of clay‑ish or silicate droplets which may include water of crystallization. I like to visualize clouds of opal, but of course there’d be no sunlight to see them by. A bit lower and you’ll fly through helium rain. Get past all that and you’re about 20% of the way down, about two Earth diameters.”

“That’s where I bump into something?”

“No, that’s the transition zone where heat and pressure convert molecular H₂ into a metallic fluid of protons embedded in a conducting ocean of electrons. Sy, how do you suppose that would affect Vinnie’s aerodynamics?”

“Destructively. If his shuttle’s skin doesn’t rupture he’d be floating rather than sinking. Net density of an intact hull and everything inside would be less than the prevailing density outside where protons are crammed together. Even powered descent would be tough.”

“Sy, that’s exactly what my crazy idea needs! Cathleen, when’s your next Crazy Theory seminar?”

“Not until next term, some time in the Fall. C’mon, Vinnie, out with it!”

Magnetism and wind map by NASA/JPL-Caltech/SwRI/John E. Connerney. Great Red Spot image added by the author.

“All right. That diagram you showed us with the red and blue spots in Jupiter’s off‑center magnetic field? It got me thinking. You get magnetism from moving charge, right, and they say Earth’s field comes from swirls in the molten iron deep underneath our crust. Jupiter doesn’t have iron so much, but you say it’s got electrons in liquid metallic hydrogen and that oughta be able to swirl, too. Maybe Jupiter has a shallow major swirl on that one side.”

“And just what do you suggest would cause a swirl like that?”

“Al was talking the other day about ‘the grand tack hypothesis‘ where Jupiter waltzed in across the inner Solar System before it waltzed back out and settled down where it’s at. Suppose while it was waltzing it hit a planetoid, maybe the size of Io. The little guy couldn’t sink and wouldn’t stick because metallic hydrogen’s liquid so it’d skip across the surface and shoot away and maybe became a moon. That’d raise a swirl like I’m talking about. See, on the map a line crossing the line between the magnetic red and blue spots could be the skip path.”

<silence>

“Hey, and the Great Red Spot, see how it’s like opposite to where I guess the hit was, that’d be like a through-planet resonance like on Mars where that Hellas meteor strike is opposite the Tharsis Bulge.”

<long pause>

“I dunno, Cathleen, Io’s so weird, do you suppose…”

“I dunno, Sy. Io has that magnetic bridge to Jupiter…”

~ Rich Olcott

Stripes And Solids

On By rolcottIn Astronomy: Planetary Science, Uncategorized3 Comments

“Any other broad-brush Jupiter averages, Cathleen?”

“How about chemistry, Vinnie? Big picture, 84% of Jupiter’s atoms are hydrogen, 16% are helium.”

“Doesn’t leave much room for asteroids and such that fall in.”

“Less than a percent for all other elements. Helium doesn’t do chemistry, so from a distant chemist’s perspective Jupiter and Saturn both look like a dilute hydrogen‑helium solution of every other element. But the solvent’s not a typical laboratory liquid.”

“Hard to think of a gas as a solvent.”

“True, Sy, but chemistry gets strange under high temperatures and pressures.”

“Hey, I always figured Jupiter to be cold ’cause it’s farther from the Sun than us.”

“Good logic, Vinnie, but Jupiter generates its own heat. That’s one reason its weather is different from ours. Earth gets more than 99% of its energy budget from sunlight, especially in the infrared. There’s year‑long solar heating at low latitudes but only half‑years of that near the Poles. The imbalance is behind the temperature disparities that drive our prevailing weather patterns.”

“Jupiter’s not like that?”

“Nope. It gets 30 times less energy from the Sun than Earth does and actually gives off more heat than it receives. Its poles and equator are at virtually the same chilly temperature. There’s a small amount of heat flow from equator to poles, but most of Jupiter’s heat migrates spherically from a 24,000 K fever near its core to its outer layers.”

“What could generate all that heat?”

“Probably several contributors. The dominant one is gravitational potential energy from everything falling inward and banging into everything else. Random rock or atom collisions generate heat. Entropy rules.”

“Sounds reasonable. What’s another?”

“Radioactives. Half of Earth’s internal heating comes from gravity, same mechanism as Jupiter though on a smaller scale. The rest comes from unstable isotopes like uranium, thorium and potassium‑40. Also aluminum‑26, back in the early years, but that’s all gone now. Jupiter undoubtedly ate from the same dinner table. Those fissionable atoms split and release heat whenever they feel like it whether or not they’re collected in one place like in a reactor or bomb. Whatever the origin, Jupiter ferries that heat to the surface and dumps it as infrared radiation.”

“Yeah or else it’d explode or something.”

“Mm-hm. The question is, what are the heat‑carrying channels? They must thread their way through the planet’s structure.”

“It’s just a big ball of gas, how can it have structure?”

“I can help with that, Vinnie. Remember a few years back I wrote about high‑pressure chemistry? Hydrogen gets weird at a million bars‑‑‑”

“Anyone’d get weird after that many bars, Sy.” <heh, heh>

“Ha ha, Vinnie. A bar is pressure equal to one Earth atmosphere. Pressures deep inside Jupiter get into hundreds of megabars. Hydrogen molecules down there are crammed so close together that their electron clouds merge and you have a collection of protons floating in a sea of electron charge. They call it metallic hydrogen, but it’s fluid like mercury, not crystalline. Cathleen, when you refer to Jupiter’s structure you’re thinking layers?”

“That’s right, Sy, but the layers may or may not be arranged like Earth’s crust, mantle, core scheme. A lot of the Juno data is consistent with that — a shell of the atmosphere we see, surrounding a thick layer of increasingly compressed hydrogen‑helium over a core of heavy stuff suspended in metallic hydrogen. About 20% down we think the helium is squeezed out and falls like rain, only to evaporate again at a lower level. The core’s metallic hydrogen may even be solid despite thousand‑degree temperatures — we just don’t know how hydrogen behaves in that regime.”

“What other kind of layering can there be?”

“Experiments have demonstrated that under the right conditions a rapidly spinning fluid can self-organize into a series of concentric rotating cylinders. Maybe Jupiter and the other gas planets follow that model and the stripes show where the cylinders intersect with gravity’s spherical imperative. Coaxial cylinders would account for the equator and poles rotating at different rates. Juno data indicates that Jupiter’s equatorial zone has more ammonia than the rest of its atmosphere. Maybe between‑cylinder winds trap the ammonia and prevent it from mixing with the next deeper cylinder.”

~ Rich Olcott