Sednoids, Rewinding the Solar System in a Simulation  0 (0)

NASA's illustration: the Kuiper Belt and Oort Cloud in relation to inner solar system. (2016)
Oort cloud, Kuiper belt, and the Solar System’s planets. NASA illustration.

Sedna and Sednoids aren’t this month’s only science news. But I saw two exciting, for me, developments; and that’s what I started talking about last week.

This week I’ll wrap up most of what I was going to say about Sednoids and “Planet X”.

Results of the James Webb Space Telescope’s observation of Sedna and two other distant dwarf planets will wait for another time: when I’m not running a fever.

Which I have been, and that’s why this was teeming with typos. I think I’ve fixed them. But if you find some, I’d appreciate it if you’d let me know in a comment.

Okay. Here’s what I was going to talk about last week:


‘As You Recall, In Our Last Exciting(?) Episode’…

1958 Solar System poster, 1888 wood engraving for Flammarion's pop science book, B movies, Superman comics. (https://dc.fandom.com/wiki/Kryptonian_Science_Council http://sacomics.blogspot.com/2010/11/jor-els-life-story.html)Recapping part of what I said last week, we’ve been learning a great deal about the Solar System.

Pluto has been relabeled as a dwarf planet and trans-Neptunian object.

As a term, “trans-Neptunian object” isn’t something I remember from my youth. On the other hand, I haven’t learned who coined it, or when.

My guess is that it’s a fairly recent addition to science-speak, since sometimes it’s spelled “transneptunian object”. And sometimes trans-Neptunian object and Kuiper belt object are used as synonyms.

This strongly suggests its spelling and usage hasn’t been standardized yet.

Anyway, objects like Pluto and Sedna, although they’re far from the inner planets, aren’t at the edge of the Solar System.1

Oort Cloud

NASA/Caltech's illustration PIA05569: Sedna Orbit Comparisons: four panels showing the location of the newly discovered (illustration released 2004) planet-like object Sedna. Moving clockwise from upper left, each panel zooms out. The first panel shows orbits of the inner planets, asteroid belt and Jupiter's orbit. The second panel shows orbits of the Solar System's giant planets, Pluto and the Kuiper belt. Below that, at lower right, are orbits of the giant planets, Pluto, and Sedna (red ellipse). Finally, at lower left, Sedna's orbit and the (probable) inner part of the Oort cloud. NASA/Caltech image released March 15, 2004, via JPL/NASA, used w/o permission.The Oort cloud is the Solar System’s outermost zone.

Unlike the inner Solar System, asteroid belt, outer Solar System, and Kuiper belt, the Oort cloud is a theoretical thing.

We haven’t observed an Oort cloud object yet: not one that’s been identified as such.

But we have seen and tracked long-period comets, which are coming from somewhere.

The Oort cloud, or something very much like it, is the least-unlikely source.

For now, I’m assuming that the Oort cloud is real; since that means I needn’t put words like “theoretical” in every other paragraph.

The Oort cloud is stuff left over from when the Solar System formed, some four and a half billion years back.

Objects in the Oort cloud are mostly small (yards to miles / meters to kilometers across) planetesimals: made mostly of materials that are gas or liquid here on Earth, like methane or water.

Some of them likely have cores that are rock or metal. That’s one reason NASA is sending a probe to Psyche. The asteroid Psyche may be the core of a planetesimal that had most of its outer ice knocked off. And that’s another topic.

Two more things about the Oort cloud.

Observations of comets and lots of math say that the outer Oort cloud should be roughly spherical, with an inner part that’s a comparatively dense disk.

Depending on context and who’s talking, the Oort cloud’s in-the-ecliptic disk is the Hills cloud, inner Oort cloud, or inner cloud.

Finally; the Oort cloud’s outer, roughly spherical, part is three light-years across.2 Give or take a bit.

Kuiper Belt and the “Inner Solar System”

WilyD's chart of the outer Solar System, from Jupiter's orbit to 60 astronomical units (AU) from the Sun. Epoch January 1, 2015.The Oort cloud’s inner disk — theoretical, so far — is in the ecliptic.

The ecliptic is the plane of Earth’s orbit, which is pretty close to the Solar System’s invariable plane.

The Solar System’s invariable plane is an average of the planets’ orbital planes. Roughly. I’m leaving out a whole bunch of stuff about barycenters and angular momentum vectors.

It’s been one of those weeks.

The Kuiper belt is another disk of material, also in the ecliptic. It was theoretical, too, until we started charting Kuiper belt objects: and realized that Pluto was one of them.

Then we discovered the Kuiper cliff, 47.8 a.u. — astronomical units, the distance between Earth and our star — from the Sun. I talked about that last week.

One of the reasons, I gather, that Pluto was reclassified as a dwarf planet is that’s got more in common with (other) Kuiper belt objects than it does with the Solar System’s planets.

Let’s see, what else? The “inner Solar System” almost always means the inner four Solar planets: Mercury, Venus, Earth, and Mars. “Outer Solar System” often refers to our planetary system’s four giant outer planets.3

Unless someone’s talking about things outside Neptune’s orbit.

That brings me to Sedna and Sednoids, tidal forces and orbits, and the (theoretical) Oort cloud’s outer reaches.

Or, rather, that almost brings me to what I was going to talk about this week.

Our Star’s Sphere of Influence

Some of the math involved in finding an object's sphere of influence.
SOMEof the math involved in determining a star’s sphere of influence.

Before astronomers found objects like Sedna, the most famous outer Solar System object was probably Nemesis.

Nemesis was (and is) a hypothetical red dwarf star or brown dwarf, orbiting the Sun every 26,000,000 years. Each time it swooped through the right (or wrong) part of the Solar System, it sent comets and asteroids hurtling toward Earth.

There are a few problems with that idea.

First, although extinction events happen, they’re nowhere near regular enough for Nemesis to be the cause. The only cause.

Second, we’re running out of places where Nemesis could be. Recent wide-field surveys have looked for Nemesis, among other objects: and so far have come up with nothing. Nothing fitting the Nemesis profile, that is.

Third, its 26,000,000 year orbit would have taken Nemesis about 1.5 light-years out from the Sun: about where scientists figure the Oort cloud’s outer edge is.

Finally, barring wildly improbable luck, Nemesis would have long since been tugged out of the Solar System.4

That’s because something about 1.5 light-years away from the Sun is near the edge our star’s gravitational sphere of influence.

“…Nothing Stands Still”: Heraclitus and the Solar System’s Shifting Border

SternFuchs's chart: distance to stars currently within 10 light-years, from 20,000 years ago to 80,000 years from now. (January 11, 2017) via Wikipedia, used w/o permission.
Distances to stars currently within 10 light-years: past, present and future. (2017) SternFuchs via Wikipedia

“τὰ ὄντα ἰέναι τε πάντα καὶ μένειν οὐδέν”
“All entities move and nothing remains still.”
“πάντα χωρεῖ καὶ οὐδὲν μένει”
“Everything changes and nothing stands still.”
(Heraclitus, quoted by Plato in “Cratylus”)

I think Heraclitus had a point, at least where things in this universe are concerned.

Take the exact location of the Sun’s sphere of influence, for example. I’ve seen it described as being ‘a few’, or about 1.5, light-years out.

But what I’ve learned about astrodynamic spheres of influence very strongly suggests that the Solar System’s gravitational border keeps shifting.

That’s because what ancient astronomers called the “fixed” stars — aren’t; although for practical purposes, on the scale of human lifetimes, the stars we see in Earth’s sky stay put.

But they’re all moving in their orbits around our galaxy’s center, and so is our Sun.

Right now, Alpha and Proxima Centauri are the closest stars. Some 28,000 years from now, they’ll be about three light-years away: their closest approach.

About 10,000 years after that, Ross 248 will be at roughly the same distance.

There’s nothing magic about “three light-years”. Some stars come much closer.

Take Gliese 710, for example. The star will, astronomers figure, be just over an eighth of a light-year away in 1,290,000 years. That’s 10,520 astronomical units: close, very roughly as far away as the currently-theoretical Hills cloud.

So I figure the Sun’s sphere of influence, the Oort cloud’s outer edge, is a shifting surface; where our star’s gravity and that of neighboring stars cancel each other out.

And that, on average, it’s about 1.5 light-years out: the top of the blue zone in the “Stars Near to the Sun” chart.

I was going to talk about this sort of thing more, but it involves a lot of math that’s beyond what I’ve learned.5 And, like I said before, it’s been one of those weeks.


Sedna and Sednoids —

Tomruen's diagram: orbits of Sedna and outer Solar System objects. (positions on Jan 1, 2017) Sedna's orbit is white, Pluto's purple, Neptune's blue. Via Wikipedia, used w/o permission.
Orbits of Sedna (white), Pluto (purple, Neptune (blue), Uranus (green)….

S. Sheppard / Carnegie Inst. of Science's diagram: Sedna, 2012 VP113, Kuiper belt and Solar System planet orbits. via Sky and Telescope. (2014 )Backing up a bit, the Kuiper belt starts around Neptune’s orbit.

Based on mathematical models, scientists expected the Kuiper belt to extend well beyond the Solar System’s planets.

Instead, they found the Kuiper cliff, 47.8 a.u. from the Sun.

Maybe it’s just a broad gap in the Kuiper belt. If so, we haven’t found that gap’s outer edge.

Now, finally, Sedna and the Sednoids.

Sedna’s current classification is dwarf planet, it’s diameter is very roughly half Pluto’s, and it’s about as close to the Sun now as it ever gets. Its perihelion, its closest approach to the Sun, will be in July, 2076.

Sedna’s orbit keeps it well beyond the Kuiper cliff, but it’s not alone. We’ve found three other Sednoids: objects with similar orbits.

Sednoid nameSemimajor axisPerihelionInclination 
90377 Sedna506 a.u.76 a.u.12 
2012 VP113262 a.u.81 a.u.24.1 
2015 TG387 Leleakuhonua1090 a.u.65 a.u.11.7 
2021 RR205990.9 a.u.55 a.u.7.6 
Sednoid orbits, expanded from table in Sky and Telescope. (October 4, 2023)

The Sky & Telescope article I started talking about last week only mentions Sedna and three other Sednoids. I’m pretty sure 2021 RR205 got left out because its perihelion is less than 60 a.u., and maybe because it’s got the smallest inclination.

Inclination: in this context, that’s how much an orbit is tilted out of the ecliptic.6

— Galactic Tides, Time, and Rewinding the Solar System

Tomruen's diagram: orbits of VP113 and outer Solar System objects. (positions on Jan 1, 2017) Sedna's orbit is white, Pluto's purple, Neptune's blue. Via Wikipedia, used w/o permission.
Orbits of 2012 VP113 (white), Pluto (purple, Neptune (blue), Uranus (green)….

Yukun Huang (University of British Columbia, Canada)'s illustration: sednoids; orbits of Sedna, 2012 VP113 ('Biden'), 2015 TG387 (541132 Leleākūhonua). (2023) via Sky and Telescope, used w/o permission.I’ve been looking for a diagram of all three Sednoids that were mentioned in that Sky & Telescope article. But so far, I’ve only found two: one for Sedna, that’s the one heading this section; and another for VP113, above.

It’s now Friday afternoon. So I’ll put that graphic quest on a back burner, and share another excerpt:

“…Huang asked: What if there is no undiscovered planet in the Kuiper belt? In that case, the orbits of the three Sednoids should have been stable over billions of years.
‘Planet X’ May Have Left Our Solar System Billions of Years Ago
Emily Lakdawalla, Sky and Telescope (October 4, 2023)

This is where I was going to talk about the Solar System’s orbit around our galaxy’s center, the search for solar siblings — stars which formed with ours — and, more to the point, how stars passing by ours in the course of the Sun’s 20.4 laps around the Milky Way.

That’s not going to happen. Not this week. Which may be just as well. I tend to ramble, and that’s yet another topic.

At any rate, objects in the Oort cloud’s outer reaches feel the gravitational tug of passing stars; an anthropomorphism that I’ll let slide.

Sometimes the objects get pulled into orbits that take them to the inner Solar System. Sometimes they’re pulled out into the void between stars.

The Sednoids, far away from the planets as they are, are far enough inside the Solar System to be safe from the ebb and flow of gravitational tides.

But they’re also too far from the Solar System’s giant worlds to have the shape of their orbits bent by close encounters. Gravitational effects of the Solar System’s giant planets would rotate the Sendoids’ orbits, and that’s about it.

Science-speak for ‘rotate their orbits’ is precession.7

One more excerpt:

“…Using a computer simulation, Huang ran the solar system backward in time for billions of years. He found that the orbits of the three known Sednoids shared some remarkably similar properties just once, in the distant past: Not long after the birth of the solar system, their perihelia clustered at the same solar longitude, and their apsidal lines (the line passing through perihelion, the Sun, and aphelion) were also nearly coincident.

“This orbital clustering is a telltale sign that a single event put the Sednoids onto their present paths, an event that happened during the solar system’s youth more than 4 billion years ago. It’s also a sign that nothing has disturbed the slow evolution of those orbits for 4 billion years. In other words, there is no undiscovered planet to be found today….”
‘Planet X’ May Have Left Our Solar System Billions of Years Ago
Emily Lakdawalla, Sky and Telescope (October 4, 2023)

I do not think this ends the search for planet-size objects in the Solar System’s borderland. But I do think it may add a page or two, at least, to the early chapters of our home’s continuing story.

That’s it for this week, apart from — you guessed it — links:


1 The Solar System’s outer reaches:

2 Oort cloud, mostly; and an asteroid:

3 Definitions:

4 A death star that probably isn’t there:

5 More than I’m going to talk about this week:

6 Sednoids and more

7 The main points are “nodal precession”, “orbital plane”, and “apsidal precession”; the rest are related topics:

Posted in Science News | Tagged , , , , , | Leave a comment

Tokamak at Culham Centre for Fusion Energy Shut Down 0 (0)

UKAEA EUROfusion's photo: JET (Joint European Torus), a magnetically confined plasma physics device at Culham Centre for Fusion Energy in Oxfordshire, UK. It is the world's largest and most powerful tokamak reactor prototype. (2023) via BBC News, used w/o permission.
Inside the JET (Joint European Torus) tokamak device at the Culham Centre for Fusion Energy.)

UK’s nuclear fusion site ends experiments after 40 years
Esme Stallard, BBC News (October 13, 2023)

‘It felt brilliant. One thing is to work on a design, another thing is to operate it.’

“Barry Green recounts the moment in June 1983 when the JET fusion laboratory in Oxford undertook its first experiment.

“For the next four decades, the European project pursued nuclear fusion and the promise of near-limitless clean energy.

“But on Saturday the world’s most successful fusion experiment will wind down….

“…In 1958, when the United States’ war research on fusion was declassified, it sent Russia, UK, Europe, Japan and the US on a race to develop fusion reactions for energy provision….”

JET/UKAEA's photo: inside their JET reactor.This is a quick update on something I wrote back in May, 2022: “TAE and ITER: A Few Steps Closer to Fusion Power“.

ITER research will keep going: in France.

I gather that ITER started out as the International Thermonuclear Experimental Reactor, and has had a name change or two since then.

England’s fusion research isn’t over, although the tokamak torus at the Culham Centre for Fusion Energy in Oxfordshire, UK, is being decommissioned.

The BBC News piece says they’ll be studying the reactor’s materials. That should show them how they’ve changed in the four decades since it was built. And that will help develop construction and maintenance procedures for future reactors.

NASA's illustration: the Kuiper Belt and Oort Cloud in relation to inner solar system. (2016)I’m keeping this short, since there’s more to say about Sedna, the Oort cloud, and all that, than I expected.

I’ve talked about fusion power and more-or-less-related topics before:

Posted in Science News | Tagged , , , | Leave a comment

Sednoids and the Mysterious Missing Planet X 0 (0)

1958 Solar System poster, 1888 wood engraving for Flammarion's pop science book, B movies, Superman comics. (https://dc.fandom.com/wiki/Kryptonian_Science_Council http://sacomics.blogspot.com/2010/11/jor-els-life-story.html)
Remembering yesteryear: a Solar System poster, the Flammarion picture, movies, and atomic angst.

As I’ve said before, this isn’t the world I grew up in.

Holf Weiher's Euler Diagram: IAU Executive Committee labels for objects in the Solar System. (October 2022)Back then, the Solar System had nine planets, assorted moons, and asteroids. Plus, of course, the sun.

Now we’ve got planets, dwarf planets, minor planets, natural satellites, trans-Neptunian objects, plutoids, comets, centaurs, and small Solar System bodies.

Just to keep things interesting, definitions for the new labels overlap. Some labels, like plutoids, didn’t catch on; and it all keeps changing as we collect more data.

This week I’ll be talking about Sednoids, another subset of trans-Neptunian object;1 along with whatever else comes to mind.


“All the News That’s Fit to Print” — and Some That Isn’t

E. Weiss drawing: 'Great Comet of 1861' (C/1861 J1, comet Tebbutt). From 'Bilderatlas der Sternenwelt', E. Weiß. (1888) via Wikipedia, used w/o permission.
Great Comet of 1861, drawing by E. Weiß. (1888)

Evening Post's 'A Startling Scientific Prediction.' (Volume LVI, Issue 26, July 30, 1898, Page 4 (Supplement)) via Papers Past“Planet X” popped up in my news feed a few times this summer, with the usual mix of science and silliness:

About that “Scientist admits” one: the Daily Express piece starts with “Known as the Nibiru cataclysm…” and ends with a link to an article in BBC Science Focus:

Robert Matthews said the odds of something big from the outer Solar System hitting Earth were “mercifully small”: with no numbers given.

My guess is that I’ve got a better chance of winning Minnesota’s Powerball® and the Irish Sweepstake on the same day. Without entering either. Speaking of which, flipping a coin apparently doesn’t yield 50-50 odds. A recent study says it’s more like 51-49.2

A few scientists say “Planet X” left the Solar System long ago. I think they’ve got a point, and that’s part of what I’m talking about this week.

But I also suspect that Planets Y and Z may be lurking in the Solar System’s borderland.

‘COMET PILLS! GAS MASKS!! GET ‘EM WHILE YOU CAN!!!’

Anonymous(?) French(?) artist's cartoon of a destructive comet. (1857)Possible planets Y, Z, and whatever would come after Planet Z, don’t fill me with existential dread.

That may take a little explaining.

Or maybe not.

Either way, let’s (briefly) recall a still-famous apocalyptic prognostication.

The year was 1910. Scientists, using recently-upgraded spectroscopy tech, detected cyanogen in the tail of Halley’s Comet.

So far, so dull.

But wait! There’s more! A famous newspaper quoted a famous scientist, and cyanogen metaphorically hit the fan.

“…The New York Times reported that the noted French astronomer, Camille Flammarion believed the gas ‘would impregnate that atmosphere and possibly snuff out all life on the planet.’

“Most scientists sought to reassure the public. The famed astronomer Percival Lowell explained that the gases making up Halley’s tail were ‘so rarefied as to be thinner than any vacuum.’

“But the damage had already been done. People rushed to purchase gas masks and ‘comet pills.’ The New York Times reported that ‘terror occasioned by the near approach of Halley’s comet has seized hold of a large part of the population of Chicago.’…”
(“Ten Notable Apocalypses That (Obviously) Didn’t Happen“, Mark Strauss, Smithsonian Magazine (November 12, 2009))

Time passed. But not the enduring appeal of scientific-sounding looming dooms and the more traditional End Times Bible Prophecies.3

Both of which I find tiresome, and that’s another topic for a week when there’s either nothing else going on: or an outstandingly silly example has been getting attention.


Sedna, Sednoids, and Orbits: Traces of a Missing World?

Yukun Huang (University of British Columbia, Canada)'s illustration: Sednoids; orbits of Sedna, 2012 VP113 ('Biden'), 2015 TG387 (541132 Leleākūhonua). (2023) via Sky and Telescope, used w/o permission.
Yukun Huang’s illustration: Sednoids; orbits of Sedna, 2012 VP113, 2015 TG387 (541132 Leleākūhonua).

‘Planet X’ May Have Left Our Solar System Billions of Years Ago
Emily Lakdawalla, Sky and Telescope (October 4, 2023)

“When Sedna was discovered more than a decade ago, its orbit — far beyond that of Neptune — baffled astronomers. Unlike most such far-out objects, Sedna never comes anywhere near Neptune. Its closest approach to the Sun is 76 a.u., more than twice Neptune’s average distance….”

“…Now, new work presented by Yukun Huang (University of British Columbia, Canada) at the 55th meeting of the Division for Planetary Sciences of the American Astronomical Society suggests that there is no such planet — at least, not anymore. While encounters with an outer-outer planet could have established the orbits of Sedna and two other, more recently discovered ‘Sednoids,’ that larger world must have been ejected from the solar system during its chaotic childhood 4.5 billion years ago….”

So far, we know of four Sednoids. I’m pretty sure 2021 RR205 got left out of this article because its perihelion is less than 60 a.u. — astronomical units, the distance between Earth and our star.

Sednoid nameSemimajor axisPerihelionInclination 
90377 Sedna506 a.u.76 a.u.12 
2012 VP113262 a.u.81 a.u.24.1 
2015 TG387 Leleakuhonua1090 a.u.65 a.u.11.7 
2021 RR205990.9 a.u.55 a.u.7.6 
Sednoid orbits, expanded from table in Sky and Telescope. (October 4, 2023)

Beyond the Kuiper Cliff: An Unexpected Void and Wandering Worlds

S. Sheppard / Carnegie Inst. of Science's diagram: Sedna, 2012 VP113, Kuiper belt and Solar System planet orbits. via Sky and Telescope. (2014 )One thing that’s distinctive about the Sednoids is that they’re well outside the Kuiper cliff.

The Kuiper cliff is 47.8 a.u. from the Sun. That’s where objects have a 1:2 resonance with Neptune.

Orbital resonance. Yeah. That’s almost technobabble, so here’s a quick definition. If something goes around the Sun once while Neptune goes around twice, it has a 1:2 resonance with Neptune.

Orbital resonances matter, since they affect the orbits of planets — and everything else on the roster of Solar System objects.

The Kuiper cliff was unexpected, since mathematical models said there should be a mess more objects beyond that 1:2 resonance. Maybe there are; but if so, they’re well beyond the ‘cliff’.

The Kuiper belt, on the other hand, wasn’t unexpected.

After Clyde Tombaugh discovered Pluto, that was in 1930, Frederick Leonard and Armin Otto Leuschner said there were probably many more objects beyond Neptune’s orbit.

WilyD's chart of the outer Solar System, from Jupiter's orbit to 60 astronomical units (AU) from the Sun. Epoch January 1, 2015.And, perhaps more to the point, in 1951 Gerard P. Kuiper published “On the Origin of the Solar System”.

He described an area where we’d expect to find comet-like objects.

“…The outermost region of the solar nebula, from 38 to 50 astr. units (i.e., just outside proto-Neptune), must have had a surface density below the limit set by equation (7). The temperature must have been about 5-10’K. when the solar nebula was still in existence (before the proto-planets were full grown), and about 40°K. thereafter. Condensation products (ices of H20, NH3, CH4, etc.) must have formed, and the flakes must have slowly collected and formed larger aggregates, estimated to range up to 1 km. or more in size. The total condensable mass is about 1029 g., but not all of this could be collected. These condensations appear to account for the comets, in size, number and composition.

“The planet Pluto, which sweeps through the whole zone from 30 to 50 astr. units, is held responsible for having started the scattering of the comets throughout the solar system. Pluto’s perturbations will have caused initial, near-circular, cometary orbits to become moderately elliptical; thereupon stronger perturbations by Neptune and the other major planets will have scattered them even more broadly….”
(“On the Origin of the Solar System“, Gerard P. Kuiper, Proceedings of the National Academy of Sciences (January 15, 1951))

Julio Ángel Fernández published a paper in 1980, saying there should be a belt of comets just outside Neptune’s orbit.

And that since for every comet falling in from the Oort cloud, 600 (probably, based on simulations) headed out into interstellar space, the just-outside-Neptune’s-orbit belt was where most observed comets came from.

A sizable roster of other scientists published other research before and after. Then, in 1992, still another researcher spotted 1992 QB1 — renamed 15760 Albion in 2018 — and so far we’ve charted upward of a thousand other objects in and beyond the Kuiper belt.4

Next: the Oort cloud, then back to Sednoids.

Charting the Borderlands of Sol

NASA/Caltech's illustration PIA05569: Sedna Orbit Comparisons: four panels showing the location of the newly discovered (illustration released 2004) planet-like object Sedna. Moving clockwise from upper left, each panel zooms out. The first panel shows orbits of the inner planets, asteroid belt and Jupiter's orbit. The second panel shows orbits of the Solar System's giant planets, Pluto and the Kuiper belt. Below that, at lower right, are orbits of the giant planets, Pluto, and Sedna (red ellipse). Finally, at lower left, Sedna's orbit and the (probable) inner part of the Oort cloud. NASA/Caltech image released March 15, 2004, via JPL/NASA, used w/o permission.
Solar System orbits, size comparison from NASA/Caltech.

The Oort cloud — when I started writing this bit, I remembered one of my favorite quotes:

“When we try to pick out anything by itself, we find it hitched to everything else in the universe”
(John Muir, quoted in a book, article, essay, letter, or something Terry Gifford (wrote?). Possibly associated with Muir’s “My First Summer in the Sierra” (1911).)

I also remembered that I have to wrap up “Sednoids and the Mysterious Missing Planet X” on Thursday. So I’ll make this brief. Brief or me, that is.

Anyway, we’ve been seeing comets — very likely since the first of us looked up as one was passing by. With no street lights dimming our night vision, comets can be spectacular.

Someone left us the first written record of a comet, but I haven’t learned who or when.

My guess is that it’s someone who worked in Sumeria, about five and a half millennia back. That’s when cuneiform was the latest thing in informational storage and retrieval tech, and when folks started systematically tracking lights in Earth’s sky and recording their data.

Sumerians were the first astronomers (and astrologers). The first we know of, at any rate.

About two centuries back, we developed new statistical analysis tools — realized that positions of the stars and planets lack the significance astrologists had assumed, and that’s yet again another topic.

Where was I?

The Oort cloud.

Anything, everything, and the universe.

Comets.

Right.

Somewhere along the line, we accumulated a mildly-complete record of showy comets. We also learned that whatever the things were, they were well outside Earth’s atmosphere.

Edmond Halley dug through available records and said that that the comets of 1531, 1607, and 1682 were the same comet. He also said that the thing would show up again in 1759, which it did.

Halley’s Comet appears in Earth’s sky every 75 to 79 years.

We’ve since learned that it’s a short-period comet. Today’s “short-period comet” label covers comets which take less than two centuries to go around the sun.

Some, like X/1991 G1, go around once every four or five years; but those tend to be so faint, it takes a decent telescope to spot them.

The bright ones tend to come through at intervals on the scale of a human lifetime, so it’s no wonder it took folks a while to realize the things were predictable.

Oddly enough, a list of numbered comets has orbital periods running from a little over three to over 365 years, and includes comet 1P/Halley. But a list of Halley-type comets doesn’t include Halley’s Comet.5

There may be an interesting story behind that. But if there is, I don’t know it: and don’t have time to dig through humanity’s archives to find it. Not this week.

Out of the Ecliptic, Beyond the Kuiper Belt

ESO/K. Meech et al.'s illustration of 'Oumuamua's path through the Solar System. (2017) via Wikimedia Commons, used w/o permission.Fast-forward from 1759 to now.

Scientists have learned that short-period comets like Halley’s generally orbit in or near the ecliptic.

That’s the plane of Earth’s orbit. It’s also pretty close to the average orbital plane of the Solar System’s planets and asteroids.

That gets us back to the Kuiper belt, which is also more-or-less in the ecliptic.

Tracking short-period comets back to their origin, we’ve learned that they come from the Kuiper belt. For the most part.

But not all comets are short-period comets. Some come in on orbits that make sense only if their origin is well beyond the Kuiper cliff. And their orbits aren’t necessarily lined up with the ecliptic.

Then there are things from the depths of interstellar space, but that’s for another time.

Many or most scientists figure there’s something they’ve been calling the Oort cloud: out beyond the Kuiper cliff, and the orbits of known trans-Neptunian objects, including Sedna.

I think the odds are good that we’ll find “Oort objects”, or whatever the label will be: but until we do, the Oort cloud is a theoretical object.

One of the reasons I strongly suspect the theoretical Oort cloud model describes something that’s real is that very-long-period comets, those with orbital periods on the order of a millennium, exist.

They come from somewhere: and a roughly-spherical cloud of leftover material from the Solar System’s formation seems like a least-unlikely explanation.6

To be Continued

NASA's illustration: the Kuiper Belt and Oort Cloud in relation to inner solar system. (2016)There’s more I was going to talk about this week: including what Yukun Huang and other scientists had to say about Sednoids, and why Planet X may be long gone.

But this is all I have time for. So this story is “to be continued” until next Saturday.

Meanwhile, the usual links; slightly focused on the Solar System’s smaller objects:


1 Labels for assorted Solar System objects:

2 What are the odds:

  • Wikipedia
  • Powerball — Minnesota Lottery
  • Fair coins tend to land on the same side they started: Evidence from 350,757 flips
    František Bartoš, Alexandra Sarafoglou, Henrik R. Godmann, Amir Sahrani, David Klein Leunk, Pierre Y. Gui, David Voss, Kaleem Ullah, Malte J. Zoubek, Franziska Nippold, Frederik Aust, Felipe F. Vieira, Chris-Gabriel Islam, Anton J. Zoubek, Sara Shabani, Jonas Petter, Ingeborg B. Roos, Adam Finnemann, Aaron B. Lob, Madlen F. Hoffstadt, Jason Nak, Jill de Ron, Koen Derks, Karoline Huth, Sjoerd Terpstra, Thomas Bastelica, Magda Matetovici, Vincent L. Ott, Andreea S. Zetea, Katharina Karnbach, Michelle C. Donzallaz, Arne John, Roy M. Moore, Franziska Assion, Riet van Bork, Theresa E. Leidinger, Xiaochang Zhao, Adrian Karami Motaghi, Ting Pan, Hannah Armstrong, Tianqi Peng, Mara Bialas, Joyce Y.-C. Pang, Bohan Fu, Shujun Yang, Xiaoyi Lin, Dana Sleiffer, Miklos Bognar, Balazs Aczel, Eric-Jan Wagenmakers (submitted October 6, 2023; (v1), revised 10 October 10, 2023 [version cited is v2]) via arXiv

3 The non-apocalypse of 1910, mostly:

4 Sedna, Sednoids, scientists, and comets:

5 Please note: astronomy is not astrology:

6 Stuff I had time for this week, and some I didn’t:

Posted in Science News | Tagged , , , , , | Leave a comment

UN Vote Surprise; October 7 Event and Student Protest 0 (0)

BBC News: https://www.bbc.com/news/world-europe-67071697 'Russia fails to rejoin UN's human rights council' (October 10, 2023); https://www.bbc.com/news/world-middle-east-67056741 'Supernova festival: How massacre unfolded from verified video and social media' (October 9, 2023).
October 10, 2023: death at a music festival, surprise at the United Nations.

Yesterday’s news from the United Nations was a surprise to me. But not as nearly-shocking as what happened back in April, 2022. I’ll get back to that.

A frame from Ukraine's National News Agency's video showing aftermath of Russia's liberation of Bucha. (April 3, 2022)Even so, I’m impressed that Russia’s continued ‘Nazi hunt’ in Ukraine has failed to win the approval of ‘right-minded’ people: particularly those running developing territories.

Russia fails to rejoin UN’s human rights council
Phelan Chatterjee, BBC News (October 10, 2023)

Russia has failed to get re-elected as a member of the UN’s human rights council.

“The state was expelled from the top human rights body last April after its forces invaded Ukraine.

“It had hoped getting a fresh three-year term would highlight divisions between UN member states over whether or not to keep supporting Ukraine.

“But Bulgaria and Albania won the two seats allocated for Eastern European countries instead.

“The vote came days after a Russian missile attack that killed 52 people in the north-eastern Ukrainian village of Hroza.

“Russia received 83 votes in favour from the UN’s 193 general assembly members, while Bulgaria got 160 and Albania got 123….”

Maps by Jurta and Pilaz: showing how countries voted on United Nations General Assembly Resolutions ES-11/1 through 3. (March 2 April 6, 7, 2022)Yesterday’s remarkable Human Rights Council vote wasn’t as surprising — almost shocking — as last year’s UN General Assembly Resolutions ES-11-1, ES-11-2, ES-11-3, (March 2, April 6-7, 2022).

Those resolutions criticized Russia’s “special military operation” in Ukraine, and demonstrated to me that this is not the world I grew up in.

Back in the day, I’d have expected at least token support for the Worker’s Paradise: along with condemnation of Yankee Imperialism with a side order of ‘it is the fault of the Jews’.

Speaking of which, killing folks at a music festival and other discontinuations of life has led to unpleasant consequences.

Which inspired something that did remind me of my ‘good old days’. Student protest.

Growing backlash over Harvard students’ pro-Palestine letter
Madeline Halpert, BBC News (October 10, 2023)

A letter from Harvard University student groups blaming Israel for violence in the region has drawn a backlash from prominent alumni and US lawmakers.

“The letter, authored by the Harvard Undergraduate Palestine Solidarity Committee, stated that students ‘hold the Israeli regime entirely responsible for all unfolding violence’.

“It was co-signed by 33 student groups….”

I still haven’t heard what Hamas had in mind when they killed folks at the Supernova festival, nearby communities, and “military installations”. Maybe they were innocently collecting hostages, and got sloppy. I don’t know.

My country’s cultural history suggests that the righteous cause may have been the “dance, music, art and drinks”, as BBC News put it. (“Supernova festival: How massacre unfolded from verified video and social media“, BBC News (October 9, 2023))

That sort of ‘Satanic’ merriment has been a burr under the saddle for Americans who seem to believe that ‘blessed are the miserable, for they shall spread misery’ is a beatitude. And that’s another topic.

The Israeli government’s failure to apologize for the October 7, 2023, Hamas attack does seem to be getting attention.

Preference and Prayer

Danijel Mihajlovic's photo: Parkland, artificial Super Trees and the Marina Bay Sands luxury hotel in Singapore's Gardens by the Bay. (2019) via Wikipedia, used w/o permission.I’d vastly prefer living in a world where sitting down over a nice cup of tea and calmly discussing why killing around 1,200 Jews and taking others hostage was okay, and why it’s the fault of the victims.

The sitting down and calmly discussing part, at least. I don’t see executing folks at a music festival as proper behavior. Even if they were enjoying the music. And kidnapping, even for some ‘noble cause’: I don’t think that’s nice, either.

There’s nothing that I can do, in what my culture calls “practical terms”, about what’s happening in the Middle East and Ukraine. And elsewhere, for that matter.

But I can pray that somehow — by what would seem like a miracle — self-righteous thugs and their minions would change their minds about killing folks they don’t approve of.

Or at least be prevented from causing more death and suffering than they already have imposed on music-lovers, kids, and others who committed the offense of being at the wrong place at the wrong time.

Uff da.

Brian H. Gill's photo, outside Sauk Centre's Saint Faustina Adoration Chapel. (2019)Seriously, though. Prayer couldn’t hurt. Might even help.

More of my take on living in a non-ideal world, but thinking we can do better:

Posted in Discursive Detours, Journal | Tagged , , | Leave a comment

Double Jupiters, a JuMBO Puzzle; Antimatter Falls Down 0 (0)

Three early astrophotos of the Orion Nebula. Left to right: Henry Draper (1880), Henry Draper (1882), Andrew Ainslie Common (1883).
Three early photos of the Orion Nebula: Henry Draper (1880, 1882), A. A. Common (1883).

Every time we develop new tech for studying this universe, we find something new. New to us, that is.

This week, I’ll be talking about unexpected Jupiter-size objects in the Orion Nebula, and why scientists at CERN dropped a few hundred antihydrogen atoms.


Baffling Binaries, Planetary Problem: JuMBOs in Orion

NASA/ESA/CSA/McCaughrean and Pearson's images: JuMBOs: Jupiter Mass Binary Objects. (2023)
“JuMBOs”, Jupiter Mass Binary Objects in the Orion Nebula.

James Webb telescope makes ‘JuMBO’ discovery of planet-like objects in Orion
Jonathan Amos, BBC News (October 2, 2023)

Jupiter-sized ‘planets’ free-floating in space, unconnected to any star, have been spotted by the James Webb Space Telescope (JWST).

“What’s intriguing about the discovery is that these objects appear to be moving in pairs. Astronomers are currently struggling to explain them.

“The telescope observed about 40 pairs in a fabulously detailed new survey of the famous Orion Nebula.

“They’ve been nicknamed Jupiter Mass Binary Objects, or ‘JuMBOs’ for short….”

For some reason, the first thing that jumped out at me in this article was “about 40 pairs”.

Giving a approximate number might mean that the reporter lost his notes and couldn’t remember how many pairs the scientists had found. Or maybe the scientists weren’t sure how many JuMBOs they’d spotted.

Or, much more likely, someone at BBC News decided that “about 40 pairs” was more appropriate for the article. Possibly because the exact number wasn’t as important as the fact that scientists said they had found “about 40 pairs”.

At any rate, I kept reading the article. Then I did a little checking.

Eventually, I learned that two scientists have found 42 pairs of (very) roughly Jupiter-mass objects in the Trapezium Cluster. And that they called them JuMBOs.

A quick glance at their pre-publication paper’s Table 1 showed that the JuMBOs ranged from 0.0006 to 0.012 solar masses. Jupiter’s mass is just under 0.001 solar mass, so calling them Jupiter Mass Binary Objects, or JuMBOs, makes sense.

And that’s another example, I think, of how much less stuffy scientists have become in the decades since I started paying attention. I mean to say: JuMBOs? Quarks? This isn’t your starched-collar 19th century science, and that’s another topic.1

Low Expectations, a Pleasant Surprise

Rogelio Bernal Andreo's photo: the constellation Orion, part of the Orion molecular cloud complex, Great Nebula in Orion, and Barnard's Loop. (October 2010)I’ve got low expectations when it comes to “science news” in unfamiliar sources: and many familiar sources, for that matter.

So I was pleasantly surprised when my news feed showed only one apparently-overstated headline.

NASA’s Webb ‘breaks physics’ with ‘JuMBO’ discovery of new astronomical objects
Ian Randall, Daily Express US (October 2, 2023)

“Researchers using NASA’s James Webb Space Telescope may have discovered a new class of astronomical objects that defy current theories of planet and star formation….”

I was even more pleasantly surprised at the job Ian Randall did, discussing this week’s JuMBO paper. He includes details I don’t remember seeing in the BBC News piece.

That said, physics isn’t broken, although some aspects of it will need revision. Probably. That’s what “the European Space Agency’s (Esa) senior science adviser told BBC News”.

“…Gas physics suggests you shouldn’t be able to make objects with the mass of Jupiter on their own, and we know single planets can get kicked out from star systems. But how do you kick out pairs of these things together? Right now, we don’t have an answer. It’s one for the theoreticians,’ the European Space Agency’s (Esa) senior science adviser told BBC News….”
(“James Webb telescope makes ‘JuMBO’ discovery of planet-like objects in Orion“, Jonathan Amos, BBC News (October 2, 2023))
[emphasis mine]

ESA’s senior science advisor is very likely right about that.

After reading that bit from the BBC News article, I wondered who ESA’s senior science advisor was, and what connection — if any — he had with the recently-published research.

So I Googled ‘ESA senior science advisor’, learned the name was Mark McCaughrean, checked his online profiles, and saw that he co-authored that study.

That establishes both his connection with the research and his qualifications for commenting on its probable impact on gas physics.

Which is good news, but it took time to learn — or confirm, if Professor McCaughrean’s ESA position should have been obvious — that “the … senior science advisor” and one of the paper’s authors were the same person.

Sorry about venting: it’s been one of those weeks, and I’ll leave it at that. Anyway, back to Professor McCaughrean, JuMBOs (Jupiter Mass Binary Objects), and PMOs (Planetary Mass Objects).

He and Samuel G. Pearson found that 9% of the PMOs they spotted in the Trapezium Cluster were binaries: double planets. Well, double objects.2

Whether those roughly-Jupiter-mass objects are “planets” will depend on who’s talking.

A Planet by Any Other Name

NASA's diagram, comparing Cancri 55 planetary system and the Solar System's Earth and Jupiter. (2006)The Solar System has nine, eight, or 10 planets: depending on whether or not I count Ceres and Pluto.

I talked about planets and how “planet” has been defined back in April, so I’ll be brief. Brief for me, that is.

The International Astronomical Union (IAU) says that a “planet” is something that:

  • Orbits our star: the Sun
  • Is massive enough for gravity to pull it into roughly spherical shape
  • Has “cleared the neighbourhood” around its orbit

The third item excludes Ceres and Pluto, which the IAU reclassified as dwarf planets back in 2006. Last I heard, the 2006 IAU definition of “planet” is still debatable and debated.

A problem I have with the current IAU definition is that it excludes all 5,000 or so objects with planetary mass we’ve catalogued to date that don’t orbit our star.

I can see practical reasons for having one word for a particular sort of object in the Solar System, and another for similar objects elsewhere. For one thing, we can send robots to the Solar System “planets”, while “exoplanets” are still out of range.

But making the distinction strikes me as a trifle silly.

It’s as if the Royal Astronomical Society defined largish watercourses in England as “rivers”, and similar watercourses elsewhere “exorivers”. Their counterparts in Canada and New Zealand might debate the definition, and that’s yet another topic.

One more thing. The International Union of Geological Sciences (IUGS) definitions of “planet” include exoplanets. And it’s definitions. Plural.

If I’m going to keep this brief, I’d better put distinctions between brown dwarfs and gas giants on hold, at least for now.3

JuMBOs and Questions

NASA, ESA, CSA, McCaughrean, Pearson's images: protoplanetary discs in the Orion Nebula. (2023)
Protoplanetary discs in the Orion Nebula: planetary systems being formed. (2023)

I figure that Pearson and McCaughrean’s paper will spark lively debate: and more study of planetary systems forming in the Orion Nebula.

That’s because what they found may suggest that the line between “planet” and “star” isn’t so much a line as it is a zone.

Jupiter Mass Binary Objects in the Trapezium Cluster
Samuel G. Pearson, Mark J. McCaughrean; European Space Research and Technology Centre (ESTEC), European Space Agency (ESA) (October 2, 2023) via arXiv

“Abstract
A key outstanding question in star and planet formation is how far the initial mass function of stars and sub-stellar objects extends, and whether or not there is a cut-off at the very lowest masses. Isolated objects in the planetary-mass domain below 13 Jupiter masses, where not even deuterium can fuse, are very challenging to observe as these objects are inherently faint. Nearby star-forming regions provide the best opportunity to search for them though: while they are young, they are still relatively warm and luminous at infrared wavelengths. Previous surveys have discovered a handful of such sources down to 3-5 Jupiter masses, around the minimum mass limit established for formation via the fragmentation of molecular clouds, but does the mass function extend further? In a new James Webb Space Telescope near-infrared survey of the inner Orion Nebula and Trapezium Cluster, we have discovered and characterised a sample of 540 planetary-mass candidates with masses down to 0.6 Jupiter masses, demonstrating that there is indeed no sharp cut-off in the mass function. Furthermore, we find that 9% of the planetary-mass objects are in wide binaries, a result that is highly unexpected and which challenges current theories of both star and planet formation.…”
[emphasis mine]

At the very least, scientists will be developing new models for planetary formation.

I doubt that we’ll see something other than the nebular hypothesis as the best — or least-unlikely — model for planetary system formation. But finding so many roughly Jupiter-mass objects in pairs means that details of the nebular hypothesis need revision.

Binary stars are common. So are binary asteroids. Binary planets — I think we’re living on one, but thinking of the Earth-Moon system as a binary is still a hard sell in some circles.

With binary stars, we’ve learned that there’s a link between mass and being in a binary system. Massive stars are more likely to be binaries than low-mass ones.

We’ve recently learned that planets can be tossed away from their stars in a planetary system’s early years, when planets are still settling into moderately stable orbits.

But, as Professor McCaughrean and others have said, we don’t have a model for how a pair of Jupiter-mass objects could get tossed into the void between stars.

Maybe those JuMBOs didn’t get thrown out of their planetary systems. Maybe they formed the way binary stars do: from a collapsing molecular cloud.4

But if they formed in roughly the same way low-mass double stars form, then we need explanations for how there are so many in the Trapezium Cluster.

Again, I suspect that distinctions between “gas giant planet” and “star” at the very least need re-examination.


Antimatter, Gravity, the Universe: and an Experiment at CERN

CERN's photo: inserting the ALPHA-g apparatus.
Inserting the ALPHA-g apparatus at CERN’s Antimatter Factory.

ALPHA experiment at CERN observes the influence of gravity on antimatter
Physics, News, CERN (September 27, 2023)

“Isaac Newton’s historic work on gravity was apparently inspired by watching an apple fall to the ground from a tree. But what about an ‘anti-apple’ made of antimatter, would it fall in the same way if it existed? According to Albert Einstein’s much-tested theory of general relativity, the modern theory of gravity, antimatter and matter should fall to Earth in the same way. But do they, or are there other long-range forces beyond gravity that affect their free fall?

“In a paper published today in Nature, the ALPHA collaboration at CERN’s Antimatter Factory shows that, within the precision of their experiment, atoms of antihydrogen — a positron orbiting an antiproton — fall to Earth in the same way as their matter equivalents….”

Well, of course antimatter falls down!! Everybody knows that everything falls down! Wasting money on some scientifical shenanigans! Money that should have been spent on something useful: like filling potholes here in Minnesota.

No, I don’t see the CERN experiment that way. Although potholes are a perennial problem in my part of the world.

On the other hand, I’m mildly surprised that CERN’s latest antimatter experiment hasn’t inspired headlines like ‘Scientists Seek God Particle’ and Collider Triggers End-of-World Fears.

Still, coverage could have been worse. Take this Times article, for example.

Collider Triggers End-of-World Fears
Eben Harrell, Time (September 24, 2008) via Internet Archive Wayback Machine

“From the flagellants of the Middle Ages to the doomsayers of Y2K, humanity has always been prone to good old-fashioned the-end-is-nigh hysteria. The latest cause for concern: that the earth will be destroyed and the galaxy gobbled up by an ever-increasing black hole next week….”

Good news, Time didn’t endorse that particular crisis du jour. Not-so-good news, the headline invoked “End-of-World Fears”.

In a way, I don’t blame science editors for deadpan reporting of doomsday predictions.

Their job is generating content that gets attention: and advertising revenue. Convincing readers that their lives, nay, this very Earth, are in deadly peril — or at least inspiring trepidation regarding newfangled science — might seem like a good idea.

It hasn’t done wonders for my opinion of mainstream media, but I don’t subscribe to The Times, The Guardian, or other shining beacons of — whatever it is they uphold.

Again, sorry about venting. I’ve had a frustrating time, trying to find background on the CERN antimatter experiment. Detailed background. If Nature wasn’t behind a paywall — well, “if wishes were horses, beggars would ride”.

I’m just glad services like arXiv exist, and allow access to folks like me.5

A Quick Look at Antimatter, From Hicks to Dirac, and Weirdness

BBC News diagram, showing structure of hydrogen atom and antihydrogen atom. (2023L
Antihydrogen is just like hydrogen, but with opposite charges.

The idea that negative matter might exist goes back at least to the 1880s, when William Hicks said matter with negative gravity was possible. If I start talking about the vortex theory of gravity and aether, then I’ll still be writing this thing when Saturday rolls around.

In 1898, Arthur Schuster used the word “antimatter” in two letters to Nature. I gather they weren’t entirely serious, but he did speculate that his “antimatter” and ordinary matter might annihilate each other. And that his “antimatter” would have negative gravity.

But, apart from the name, Schuster’s antimatter had little to do with what scientists at CERN have been studying.

Current ideas of antimatter go back to “The Quantum Theory of the Electron“, Paul Adrien Maurice Dirac, Proceedings of the Royal Society A (February 1, 1928).

Since then, most scientists figure antimatter and gravity interact pretty much the way ordinary matter and gravity do.

Things get — complicated — after that.

And a bit weird, including treating negative energy modes of the electron field as if they’re going backward in time.6

The point is that, although most scientists were pretty sure that antimatter would fall down, nobody had proven that this was true. And some of the math describing how antimatter works is distinctly non-intuitive.

(Most) Antihydrogen Atoms Fell Down

CERN's diagram: showing how they make antihydrogen atoms and store them before dropping them. Via BBC News, used w/o permission.
Highly simplified diagram of CERN’s antihydrogen manufacture, storage and testing process.

I had been looking for discussions of how CERN makes antihydrogen atoms, but didn’t find a photo of their antiproton decelerator until late Thursday afternoon.

That page on the CERN site was more a backgrounder than a detailed description; so I’ll just rephrase what I found in that BBC News piece, and in CERN press releases.

The folks at CERN sent antiprotons and positrons — particles that are like electrons, but have a positive charge — streaking along “pipes” at just under the speed of light.

When the two streams reached the experiment area, the antiprotons and positrons were slowed down to more manageable speeds, mixed, and stored in a confinement container.

Just how that works, I don’t know. That’s why I was looking for more detailed discussions.

I gather that the confinement device is a Penning trap: a sort of magnetic bottle for charged particles. Or, in this case, anthydrogen atoms.

Going mostly from what I read in the CERN press releases, scientists trapped antihydrogen atoms in their Penning trap, in seven batches of about 100 each. Each time they had a batch, they released it over a period of 20 seconds.

They’d run computer simulations for what would happen to hydrogen atoms, the sort with proton nuclei and one electron, under those conditions. The simulations showed 20% flying out the top of the trap, 80% dropping out the bottom.

That’s what how the antihydrogen atoms acted, too.

This is a very strong indication that antihydrogen interacts with gravity the way normal matter does.

That’s not, however, the end of this research. Scientists at CERN can’t be sure that antihydrogen falls at the same rate as normal matter. That’s something they’ll be testing, when they develop more precise instruments.7

Mystery of the Missing Antimatter

Andrew Z. Colvin's simulated view of the observable universe. Our galaxy is in the Virgo Supercluster. The Virgo Supercluster is too small to be seen at this scale. (February 8, 2011)
The observable universe, Andrew Z. Colvin’s simulated view. The Virgo Supercluster is invisible at this scale.

Antimatter, the sort studied at CERN, happens naturally whenever we have high-energy particle collisions: when cosmic rays hit Earth’s atmosphere, for example.

There’s a disaster movie plot lurking there, along the lines of “Cosmic Monsters Meet 2012”, and that’s yet again another topic.

These extremely tiny amounts of antimatter routinely form, touch ordinary matter, and then both disappear in a (tiny) flash of gamma rays.

But apart from those ephemeral bits of antimatter, our part of the universe is pretty much all ordinary matter. Except for dark matter and dark energy and that’s a whole mess of topics I’ll leave for another time.

Our neighborhood being 100% matter is good for us, considering how much energy would get released if antimatter existed locally in visible quantities.

But it’s a serious problem for theoretical physicists and cosmologists. Various flavors of the Big Bang theory are still the best fit with observed phenomena.

Which reminds me: Big Bang theory isn’t the only cosmological model around.

Someone’s probably still supporting plasma cosmology, for example. It says the universe has always been and always will be, cycling between being big and small. Only problem is, plasma cosmology doesn’t fit observed phenomena.

Big Bang models fit observed phenomena: except for the notable lack of local antimatter.

There should be about equal amounts of matter and antimatter around. But there isn’t. Apparently.

Quite a few explanations have been suggested.

One is that this universe has some regions that are (almost) all matter, others that are (almost) all antimatter. If this is so, we could observe gamma radiation generated at boundaries between the regions. Astronomers have looked.

There aren’t any such boundaries in our part of this galaxy.8

‘Where’s the Antimatter?’ — Broadening the Search

NASA, ESA, CSA, I. Labbe (Swinburne University of Technology), R. Bezanson (University of Pittsburgh)'s image (processed by Alyssa Pagan (STScI)): detail of James Webb Space Telescope NIRCam's Abell 2744 ('Pandora's Cluster') image; a gravitational lens magnifying distant galaxies. (February 15, 2023)But there’s much more to this universe than the Milky Way Galaxy.

Our Milky Way and the Andromeda Galaxy are the two major galaxies in the Local Group, a set of galaxies about 10,000,000 light-years across.

The Local Group is part of the Virgo Supercluster, which may in turn be part of the Laniakea Supercluster. Never mind the size of those things.

At some point, from a human perspective, things are simply “big”. Or, in this case, cosmic.

Maybe astronomers will map gamma ray emitting boundaries between parts of the Virgo Supercluster, or between neighboring superclusters. That would would at least hint that we’re looking at a matter-antimatter boundary.

Or maybe matter and antimatter domains are at a larger scale. That could answer the ‘where’s the antimatter’ question.

But it might also give cosmologists the sort of problems they have explaining things like The Giant Arc: a feature that’s around 3,300,000,000 light-years across.

That’s too big. According to the cosmological principle.9

The cosmological principle, the idea that at large scales this universe looks the same to everyone, has been a pretty good match with observed reality since Newton’s day.

Then, recently, we stated noticing things like the Giant Arc. My guess is that we’re in the process of leaning something new about this universe. Several somethings, most likely.


Ptolemy, C. S. Lewis, Cosmic Scale, and Assumptions

Frontispiece for 'Historia Mundi Naturalis', Pliny the Elder (first century AD), published Sigmund Feyerabend, Frankfurt am Main. (1582)
Frontispiece (1582) for “Historia Mundi Naturalis”, Pliny the Elder (first century AD).

'L'image du monde,' Gossuin de Metz. (14th century copy of a 13th century original)It’s been a few years since I saw ‘Christians believe Earth is flat’ in a chat.

Partly, I figure, because I’m not all that active on social media.

But I’d be pleasantly surprised if similar assumptions regarding Christians, Christianity, and science have finally faded.

Earth 2.0: Bad News for God
Jeff Schweitzer, Huffington Post (July 23, 2015)
“…Let us be clear that the Bible is unambiguous about creation: the earth is the center of the universe, only humans were made in the image of god, and all life was created in six days. All life in all the heavens. In six days….”

I’ve been talking about stars and planets in the Orion Nebula, a massive interstellar cloud some 1,350 light-years — drat! I forgot something: and that will wait for another time.

Anyway, I’ve been talking about stars so distant that their light takes more than a millennium to reach us. And galaxy clusters that are many orders of magnitude bigger.

Maybe it’s time for me to try explaining why living in a big universe doesn’t bother me. Even though I am a Christian. 😉

Or, rather, maybe it’s time for me to share what C. S. Lewis wrote in the mid-1940s.

I suspect the conversation between Lewis and his friend is a fictional summary of many similar discussions. But I think the points are as valid now as they were three-quarters of a century back. I’m picking up the text with remarks by the friend.

“…’You see, the real objection goes far deeper. The whole picture of the universe which science has given us makes it such rot to believe that the power at the back of it all could be interested in us tiny little creatures crawling about on an unimportant planet! It was all so obviously invented by people who believed in a flat earth with the stars only a mile or two away.’

“‘When did people believe that?’

“‘Why, all those old Christian chaps you’re always telling about did. I mean Boethius and Augustine and Thomas Aquinas and Dante.’

“‘Sorry,’ said I, ‘but this is one of the few subjects I do know something about.’

“I reached out my hand to a bookshelf. ‘You see this book,’ I said, ‘Ptolemy’s Almagest. You know what it is?’

“‘Yes,’ said he. ‘It’s the standard astronomical handbook used all through the Middle Ages.’

“‘Well, just read that,’ I said, pointing to Book I, chapter 5.

“‘The earth,’ read out my friend, hesitating a bit as he translated the Latin, ‘the earth, in relation to the distance of the fixed stars, has no appreciable size and must be treated as a mathematical point!’

“There was a moment’s silence.

“‘Did they really know that then?’ said my friend. ‘But — but none of the histories of science — none of the modern encyclopedias — ever mention the fact.’

“‘Exactly,’ said I. ‘I’ll leave you to think out the reason. It almost looks as if someone was anxious to hush it up, doesn’t it? I wonder why.’…”
(“Religion and Science”, C. S. Lewis, The Coventry Evening Telegraph, p. 4 (January 3, 1945) via “God in the Dock”, C. S. Lewis, edited by Walter Hooper (1970))

I’m quite sure that some Christians in Ptolemy’s day weren’t up to speed on the latest thing in natural philosophy.

But I figure that at least some knew about his work, they’d all have been glad to know that Christianity would be decriminalized in a few centuries, and that’s still another topic.

“…Its Inhabitants Like Grasshoppers….”

NGC 4848 and other galaxies, image by Hubble/ESA.
NGC 4848 and other galaxies.

Then there’s what we knew about God, long before Ptolemy’s day.

“Indeed, before you the whole universe is like a grain from a balance,
or a drop of morning dew come down upon the earth.
“But you have mercy on all, because you can do all things;
and you overlook sins for the sake of repentance.”
(Wisdom 11:2223)

“The one who is enthroned above the vault of the earth,
its inhabitants like grasshoppers,
Who stretches out the heavens like a veil
and spreads them out like a tent to dwell in,”
(Isaiah 40:22)

And that’s all for this week, apart from the seemingly-inevitable links:


1 Names, a nebula, JuMBOs, and a little history:

2 Discovering a mystery in the Orion Nebula:

3 Stars and planets, names and defitions:

4 Doubles, data, definitions and hypotheses:

5 Science, potholes and the news:

6 Science and speculation:

7 Looking back and ahead:

8 Cosmic monsters and cosmology:

9 Galaxies and this universe:

Posted in Exoplanets and Aliens, Journal, Science News, Series | Tagged , , , , , , , | Leave a comment