Mushballs

I first ran into the concept that not all planets had hard, rocky surfaces -- like Earth, and the ones I was all too familiar with from scientific documentaries like Lost in Space -- when I was about eight.

It was in one of those kids' books about astronomy, and I found the whole thing absolutely fascinating.  Mercury, Venus, Earth, and Mars were small, solid, and made mostly of silicate rocks.  Certainly, the four have their dramatic differences -- airless, scorched Mercury; Venus with its brutally hot, carbon-dioxide-rich atmosphere and clouds of sulfuric acid; temperate, lovely Earth; and chilly, windswept, dusty Mars.  But all four, at least to some extent, fit the picture I'd had of what a planet should look like.

But then the outer four -- Jupiter, Saturn, Uranus, and Neptune -- confounded that completely.

All four are gas giants, massive planets with no solid surface (or, if there is one, it's buried so deep as to be all but inaccessible).  The atmospheres are largely hydrogen, helium, carbon monoxide and dioxide, ammonia, and methane.  They rotate fast -- Jupiter, the largest planet, rotates once on its axis every ten hours -- and this, combined with some serious convection currents, creates enormous storms, the most famous of which is Jupiter's Great Red Spot, which is large enough to swallow the Earth entirely and has wind speeds over four hundred kilometers per hour.

[Image is in the Public Domain courtesy of NASA/JPL]

Even the gas giants' cores aren't like the Earth's; ours is predominantly iron and nickel, while Jupiter -- and, it is surmised, the other three -- have a core largely composed of hydrogen compressed to the point that its electrons delocalize and it begins to act like a metal.  (This metallic hydrogen core is thought to be the source of Jupiter's enormous magnetic field.)

So my picture of the outer four planets was forever changed.  They were huge, churning blobs of gas, not solid at all.  Saturn, in fact, has such a low overall density that if you could find a swimming pool big enough, it'd float.  Then, my mind was further blown when I was twenty and first saw Carl Sagan's Cosmos, where he suggested that such a planet might still host life -- floating or flying creatures that could ride the wild thermal updrafts, and somehow metabolize the anoxic stew of gases they live in.

What's coolest of all, though, is that our understanding of the gas giants is still being refined.  A study out of the University of California - Berkeley found that certain areas of Jupiter's atmosphere are strangely ammonia-depleted.  This is unexpected -- the constant turbulence, you'd think, would result in uniform mixing, just like stirring a cup of coffee distributes the cream and sugar evenly throughout.  If there are areas low in ammonia, what is keeping them that way?

The researchers found a mechanism that might be responsible.  Updrafts in low-pressure zones might, just as they do on Earth, create hailstorms.  But everything's bigger on Jupiter -- bigger than Texas, even -- and these enormous updrafts allow the formation of huge "mushballs" composed primarily of frozen ammonia and water that, once they are too heavy to keep aloft any more, fall down into the lower layers of the atmosphere, leaving upper regions depleted.

So unlike on Earth, where a three-centimeter hailstone is considered pretty huge, these would be between the size of a softball and a basketball.

"The mushball journey essentially starts about fifty to sixty kilometers below the cloud deck as water droplets," said Chris Moeckel, lead author of the paper on the phenomenon, which appeared in Science Advances this week.  "The water droplets get rapidly lofted all the way to the top of the cloud deck, where they freeze out and then fall over a hundred kilometers into the planet, where they start to evaporate and deposit material down there.  And so you have, essentially, this weird system that gets triggered far below the cloud deck, goes all the way to the top of the atmosphere and then sinks deep into the planet...  Imke [de Pater, Moeckel's advisor] and I both were like, 'There's no way in the world this is true.'  So many things have to come together to actually explain this, it seems so exotic.  I basically spent three years trying to prove this wrong.  And I couldn't prove it wrong."

So Sagan's floaters and flyers would not only have to deal with Jupiter's screaming winds and monstrous lightning storms, they'd have to dodge volleyball-sized hailstones.

Not the most hospitable place in the world.

It's pretty cool that even our own Solar System still has the capacity to amaze us.  The more we learn, the more questions we have.  It's like Neil deGrasse Tyson said; "As our knowledge grows, so too does the perimeter of our ignorance."  And sometimes it's a simple, innocuous-seeming question -- like, "why are some parts of Jupiter's atmosphere low in ammonia?" -- that leads to a huge shift in our picture of how some part of the universe works.

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Time to act

I know we really don't need anything else to worry about.  World events have been depressing enough, and here in the United States we've got an election on Tuesday that is making me pop Xanax as if they were Skittles.  But I ran across something in a book I'm reading that was absolutely jaw-dropping, and not in a good way, and I knew I would be seriously remiss in not writing about it here.

I mentioned a few days ago (in a post about some bizarre volcanoes in the East African Rift Zone) that I've been reading Tamsin Mather's wonderful book Adventures in Volcanoland: What Volcanoes Tell Us About the World and Ourselves.  Mather's specialty is monitoring gas production from volcanoes, and using the composition of offgassed material to gather information about magma characteristics and the likelihood of eruptions.  She's traveled all over the world collecting and analyzing samples, comparing hotspot volcanoes (like the ones in Hawaii) to rift volcanoes (like Ol Doinyo Lengai in Tanzania) to trench/subduction volcanoes (like Etna, Vesuvius, Krakatoa, Fujiyama, the Andes, and the North American Cascades).  Her research puts her in position as one of the world's foremost and most knowledgeable experts on volcanic offgassing, and what it means for our understanding of what is going on inside the Earth's mantle.

In her book, she not only references currently-active volcanoes, but prehistoric eruptions -- and one of those she discusses is the astonishingly huge Siberian Traps.  

[Image licensed under the Creative Commons OlgaChuma Ольга Чумаченко, Плато Путорана-3, CC BY-SA 3.0]

This eruption, of a type known as a large igneous province or flood basalt, happened 252 million years ago, at the end of the Permian Period.  Flood basalt eruptions occur when something rifts the crust of the Earth and deep-source, extremely hot basaltic (low silica content) lava flows out.  This lava is incredibly fluid, and fills up valleys like water fills a bowl.  In the case of Siberia, it was a quantity that beggars belief; current estimates stand at around four million cubic kilometers of lava.  The disaster this caused was amplified by the fact that prior to the eruption, the Earth had had a long period of warm, wet climates pretty much worldwide, facilitating the growth of widespread swamps and rainforests.  The age when this occurred is called the Carboniferous Period, so named because all that dead compressed plant matter locked up gigantic quantities of atmospheric carbon, forming enormous seams of coal.

When the Siberian Traps erupted, the lava ripped its way through those massive coal deposits, and the carbon they contained was suddenly returned to the atmosphere as carbon dioxide.  Mather writes:

Estimates of total carbon dioxide emissions over the million-year-scale lifetimes of these basaltic floods are in the region of tens to hundreds of trillion tonnes...  Estimates of varying emission rates over the very long lifetimes of these provinces are harder to make than the totals, but one recent study put the maximum emission rate during the Siberian Traps at around eighteen billion tonnes per year.

The result was widespread disruption of the climate, global marine anoxia, and the largest mass extinction ever -- the Permian-Triassic Extinction, which wiped out on the order of ninety percent of life on Earth.

The kicker comes in the very next paragraph, when Mather tells us that the rate of carbon dioxide production from the most massively devastating volcanic eruption on record, the rock from which covers an area of seven million square kilometers, is half the rate our current fossil fuel use is currently churning out carbon dioxide.

I don't exaggerate when I say I had to read that passage three times before I was convinced I'd understood her correctly.

I've all too frequently heard laypeople give a sneering chuckle at the climatologists, saying stuff like, "What a lot of bullshit.  One volcanic eruption emits more carbon dioxide than all the cars on Earth do."  They rarely cite a source, and when they do it's from something like the fossil-fuel-industry-funded Heartland Institute, but -- because this opinion is a great excuse for continuing to do stuff the same way we always have -- they almost never get challenged on it.

It's astonishing how easy it is to accept a false viewpoint when it gives you a comforting reason not to do anything inconvenient to your lifestyle.

But here's the straight scoop from Tamsin Mather, who (allow me to reiterate) is a volcanologist who specializes in analysis of volcanic offgassing:

Despite the wide error bars in our estimates of the global rate of volcanic carbon degassing, what we can know is that these natural emissions pale into insignificance compared to what humans produce.  In 2019, human fossil-fuel burning released over 35 billion tonnes of carbon dioxide into our atmosphere.  This is seventy times more than even our most generous current estimates of global magmatic carbon degassing.  In 2022, the aviation industry alone emitted 800 million tonnes of carbon dioxide, eclipsing estimates of that from our planet's background tectonism before even considering other sectors of human industry.  We cannot look to Earth's volcanism today to reassure ourselves that our rate of carbon emission might not be too much of a change in terms of our planet's natural cycles.  Powerful as the forces of tectonics that daily drive the slow creep of plate movement and volcanic activity across the globe are, the human race has currently surpassed them in terms of its carbon dioxide flux to the atmosphere.  It is apposite to reflect upon the level of responsibility that should appropriately come with the level of power attained by our species that, by this carbon metric, overwhelms all Earth's volcanoes.

Despite this, we have a candidate for president here in the United States -- I doubt I need to tell you which one -- who has stated he wants to discontinue investment in renewable energy and withdraw from the Paris Accords, and frequently says "Drill baby drill, and frack frack frack!" to cheering crowds.

Anyhow, I'm sorry to post alarming stuff, but perhaps now isn't such a bad time after all.  We have the chance to make a difference not only by our actions and choices, but in the voting booth.  It put me in mind of a conversation that occurs in my novel In the Midst of Lions, which seems a fitting way to end this post:

Mary Hansard's face registered near panic.  "It's not just here.  It’s everything we know.  Soon it’ll all be gone, and if we don’t find a way out, us with it.  We've got to do something, now.”

Soren glanced at Dr. Quaice.  “Okay, this is scaring the shit out of me.”

Mary tightened her grip on Soren’s sleeve.  “Good.  Good.  You should be scared.  Scared people act.” She hitched a sob.  “Complacent people die.”

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Looking for a biosignature

From Gordon's Obsession #1 (paleontology) yesterday, today we're moving on to Gordon's Obsession #2: outer space and extraterrestrial life.

No, unfortunately, I'm not about to announce we've located the Andorian home world.  Maybe next time.

We're returning to this favorite topic of mine because of a paper this week in Astrophysical Journal Letters by a team led by Lisa Kaltenegger, of the Carl Sagan Institute of Cornell University, right in my part of the world in upstate New York.  Kaltenegger et al. describe models they've developed to refine how we look for Earth-like exoplanets -- by trying to figure out what our own world would have looked like from the depths of space during its entire geological history.

In "High-Resolution Transmission Spectra of Earth Through Geological Time," Kaltenegger's team recognizes the phenomenon we've discussed here before -- that seeing farther out into space means seeing further back into time.  An intelligent, technological alien species as little as 150 light years away wouldn't have any way of knowing that the Earth hosted a complex civilization with its own sophisticated scientific and technological capabilities, because they'd be seeing us as we were 150 years ago -- before the invention of long-distance radio-wave communication.  To them, the Earth would be a small rocky planet that was entirely silent, and apparently, devoid of life.

So are we making the same mistake with the exoplanets we're seeing?  And is there a way to get beyond that, and find "biosignatures" -- detectable traces of life on a far-distant world?

The key, says Kaltenegger, is in the world's atmosphere.  As the light from its host star passes through the thin envelope of gases surrounding the planet, the light is altered; each kind of gas has a specific set of frequencies it can absorb, and those are selectively removed from the stellar light, creating a dark-line or absorption spectrum.  This gives a fingerprint of what gases are there -- and, potentially, tells us what's going on down on the planet's surface, including whether or not there's anything alive.

The data they're using comes primarily from two sources -- the orbiting James Webb Space Telescope, and the Extremely Large Telescope out in the Atacama Desert of Chile.

I don't know about you, but the name of the latter always makes me laugh.  I'm picturing the scientists coming up with a name for the observatory after it was complete:

Scientist #1:  So, what are we gonna name our telescope?
Scientist #2:  How about naming it after Edwin Hubble?
Scientist #1:  No, that one's already taken.
Scientist #2:  Well, what's this thing's most outstanding feature?
Scientist #1:  It's extremely large.
*pause*
Scientist #1 and #2, together:  Heyyyyyy......!

But I digress.

Kaltenegger's team is looking for the presence of highly-reactive gases -- oxygen being the most obvious example -- that wouldn't be in an atmosphere unless something was continually pumping it out.  While there could be a non-biological way to inject large quantities of oxygen into an atmosphere, the better likelihood is some analogue to photosynthesis.

In other words, life.

The nice thing about this approach is that the presence of oxygen would have been detectable here on Earth over a billion years ago -- thus, potentially detectable by technological aliens from up to a billion light years away.  That's quite a window.  "Even though extrapolations from our findings suggest that one out of five stars hosts a planet which could be like Earth, it would be extremely surprising if all of them were at our Earth’s evolutionary stage," Kaltenegger said.  "So taking Earth’s history into account to me is critical to characterize other Earth-like planets."

What the team did is predict what the absorption spectra of the Sun's light would look like after passing through the Earth's atmosphere during the various periods of our prehistory -- the anoxic period (prior to the evolution of photosynthesis), the time during which aerobic life was present but uncommon, the transition to the land & evolution of plants, and so on, up through the Industrial Revolution, when (as James Burke put it in After the Warming) "instead of the atmosphere doing things to us, we started doing things to it."

The technique is not without its difficulties, however, most notably that the absorption spectrum of one of the biologically-produced reactive gases they studied -- methane -- is awfully close to that of water.  So teasing apart what's the signature of a ubiquitous compound, and what's the actual fingerprint of life, may not be simple.

What's certain is that we've only scratched the surface of what's out there.  At present there are a few more than 4,000 exoplanets identified, a lot of which are gas-rich Jovian planets that are likely not to have a solid surface.  (The reason for this is that the two main techniques for locating exoplanets, stellar occlusion and detection of a "wobble" in the star's position, work much better if the planet in question is large, biasing us against detecting small rocky worlds like our own.)  But if Kaltenegger is right that twenty percent of stars have Earth-sized planets, that's a lot of potential homes for alien life.

I don't know about you, but to me, that's tremendously exciting.  Even if we can't detect Vulcans and Klingons and Andorians yet, we might just be able to see if there's life at all out there.

And I'd be satisfied with that.  Just knowing we're not all alone in the cosmos would be reassuring, even if we don't know what that alien life is like, or whether they might be looking back at us through their own telescopes.

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This week's Skeptophilia book recommendation is an important read for any of you who, like me, (1) like running, cycling, and weight lifting, and (2) have had repeated injuries.

Christie Aschwanden's new book Good to Go: What the Athlete in All of Us Can Learn from the Strange Science of Recovery goes through all the recommendations -- good and bad, sensible and bizarre -- that world-class athletes have made to help us less-elite types recover from the injuries we incur.  As you might expect, some of them work, and some of them are worse than useless -- and Aschwanden will help you to sort the wheat from the chaff.

The fun part of this is that Aschwanden not only looked at the serious scientific research, she tried some of these "cures" on herself.  You'll find out the results, described in detail brought to life by her lucid writing, and maybe it'll help you find some good ways of handling your own aches and pains -- and avoid the ones that are worthless.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Five-part wake-up call

I am not superstitious -- something that regular readers of Skeptophilia would hardly need pointed out -- but sometimes I think the universe is trying to send me a message.

I got on Facebook yesterday morning, and found that a friend of mine had posted, "I can't wait until the pandemic is over, so we can go back to doing absolutely nothing about climate change."  I gave that a rueful chuckle, and then decided to buckle down and get to work finding a topic for today's post.  I headed over to the Reddit page /r/science, often a good place to start when trying to find links to recent academic papers, and within five minutes found no less than five references that apply directly to climate change.

Let's start with the less alarming ones first -- and as you'll see, even the less alarming ones are pretty damn terrifying.

First, we have a press release over at EurekAlert, the science news site of the American Association for the Advancement of Science, which looked at an event in the Earth's distant past.  At the boundary between the Ordovician and Silurian Periods, about 444 million years ago, there was a massive die-off that ranks among the "Big Five" extinction events.  It's not one that most people know about, however -- not only was it a long time ago, it's eclipsed by the more famous Permian-Triassic Extinction (that by some estimates eradicated 95% of all the species on Earth) and the Cretaceous Extinction, that wrote Finis: Exeunt on the Age of the Dinosaurs.

The Ordovician/Silurian Extinction has been a bit of a mystery.  Not only are good geological strata from that long ago uncommon, it was unclear from what geologists did have what it all meant.  There was pretty good evidence of rapid seesawing between hot temperatures and massive glaciation, but what kicked it off?

[Image licensed under the Creative Commons Gérald Tapp, Icebergs, CC BY-SA 3.0]

We now have at least a partial answer to that.  The cause seems to have been worldwide oceanic anoxia.  At that point, all life was marine; so when the ocean's oxygen level crashed, it was catastrophic.  From the chemistry of the sedimentary rocks of the period, it looks as if a huge volume of marine water had essentially no dissolved oxygen.

"Thanks to this model, we can confidently say a long and profound global anoxic event is linked to the second pulse of mass extinction in the Late Ordovician," said study co-author Erik Sperling of Stanford University.  "For most ocean life, the Hirnantian-Rhuddanian boundary [between the end of the Ordovician and the beginning of the Silurian] was indeed a really bad time to be alive."

If the relevance of this study to our situation today isn't apparent, the press release wallops you over the head with it:

Beyond deepening understandings of ancient mass extinction events, the findings have relevance for today: Global climate change is contributing to declining oxygen levels in the open ocean and coastal waters, a process that likely spells doom for a variety of species.

Then there's the press release from McGill University about another extinction event, the one that happened at the boundary between the Triassic and Jurassic Periods, 201 million years ago.  This one was also a bit of a mystery, but now the researchers have a smoking gun.  Guess what it is?

Changes in the atmosphere.

Here, massive volcanic eruptions (okay, "massive" isn't sufficient; "fucking huge" comes close) occurred as the Central Atlantic Rift Zone opened up, which was eventually to push apart Europe and Africa from North and South America, creating the Atlantic Ocean.  But this research indicates that the initial eruption happened over only five hundred years, and spewed out 100,000 cubic kilometers of lava.

That's a cubical block, one kilometer on each edge, but 100,000 of them.

Like I said.  Fucking huge.

What the problem was, other than for anything in the way of the lava flows, was the carbon emissions.  Not only does lava itself usually contain dissolved carbon dioxide that is released upon eruption, there's all the carbon generated by the lava burning up plants and other organic material.  The amount of carbon pumped into the atmosphere by this event was said by the press release to "be equivalent to the [predicted] total produced by all human activity during the 21st century."

When I got to this sentence, I said, and I quote, "What?"  The amount of carbon released by human activity in the 21st century is predicted to be equal to the amount generated by a 100,000 cubic kilometer lava flow, only five times faster?

At this point, I said some other stuff, which I won't include because I've already said "fucking" twice in this post.

Now, on to the ones that apply directly to our situation here and now.

First, a study out of the University of Sydney of estuaries, the points where freshwater rivers run into oceans.  These are biologically productive areas, homes to not only abundant sea life but fisheries industries that support coastal economies.  What this study found is that the water in estuaries is warming at twice the rate of the rest of the world's oceans -- which could be catastrophic.  In the words of the press release:

The researchers say that changes in estuarine temperature, acidity and salinity are likely to reduce the global profitability of aquaculture and wild fisheries.  Global aquaculture is worth $US243.5 billion a year and wild fisheries, much of which occurs in estuaries, is worth $US152 billion.  More than 55 million people globally rely on these industries for income.

Be aware, too, that this temperature increase is not a prediction.  It's already happened.  "This is evidence that climate change has arrived in Australia; it is not a projection based on modelling, but empirical data from more than a decade of investigation," said Elliot Scanes, who co-authored the paper, which appeared this week in Nature Communications.  "This increase in temperature is an order of magnitude faster than predicted by global ocean and atmospheric models."

Last, there are two studies, both in the journal Nature.  One focused on projections of biodiversity loss in Africa and predicted that the crash was set to happen a lot sooner in the tropics than initially thought, and that the losses would be significantly impacting economies in the 2030s.   Like, ten years from now.  And it's not as if we here in the Frozen North will be spared; the same models predicted this devastation to spread to temperate ecosystems by 2050.  The final study modeled the economic impact of the current target of keeping the global average temperature increase between 1.5 and 2 C over the next eighty years.  I'd like to quote directly from this one, because paraphrasing just wouldn't have the same impact:

Results show that following the current emissions reduction efforts, the whole world would experience a washout of benefit, amounting to almost 126.68–616.12 trillion dollars until 2100 compared to 1.5 °C or well below 2 °C commensurate action.  If countries are even unable to implement their current NDCs, the whole world would lose more benefit, almost 149.78–791.98 trillion dollars until 2100.

The authors of this study call keeping the warming threshold below 1.5 C "a matter of simple self-preservation."

Five studies, all basically with the same message: when this happened in the past, the consequences were horrifying; it's happening now; and we damn well better get up off our asses and do something about it.  Not that this is likely with Emperor Donald the Demented in charge, not to mention his corporate-boot-licking yes-men and women in Congress.

The most frustrating thing for me about all of this is that we've known about all this for ages.  Thirty years ago, Irish science historian James Burke released his amazing two-part documentary After the Warming, which was prescient in so many ways that it beggars belief.  But these lines always have stood out to me:   "Where they [are getting] it really wrong is the argument over whether the greenhouse effect is happening [now]... which is irrelevant.  The question is what to do about the fact that scientific opinion thought that it would strike sooner or later.  Still, for some people, that wasn't good enough reason to spend money preparing for the eventuality, even though they paid to insure their lives, their homes, and their national defense against much less likely events."

So it's an open question if we'll do anything now, given our abysmal track record of taking the information we already have and acting on it.  I'm hoping that the information campaigns to bring this to the attention of the public, both by humble bloggers like myself and the scientific experts who know the most, are waking people up, even if only a few at a time.

My only fear is that a few at a time won't be enough to stave off catastrophe.

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This week's Skeptophilia book recommendation of the week is brand new -- only published three weeks ago.  Neil Shubin, who became famous for his wonderful book on human evolution Your Inner Fish, has a fantastic new book out -- Some Assembly Required: Decoding Four Billion Years of Life, from Ancient Fossils to DNA.

Shubin's lucid prose makes for fascinating reading, as he takes you down the four-billion-year path from the first simple cells to the biodiversity of the modern Earth, wrapping in not only what we've discovered from the fossil record but the most recent innovations in DNA analysis that demonstrate our common ancestry with every other life form on the planet.  It's a wonderful survey of our current state of knowledge of evolutionary science, and will engage both scientist and layperson alike.  Get Shubin's latest -- and fasten your seatbelts for a wild ride through time.

Dark clouds

I still remember when I was about twenty years old, and I first heard about Carl Sagan's proposal to terraform Venus.

On first glance, this is a crazy idea.  Venus brings new meaning to the word "inhospitable."  Its average surface temperature is 462 C.  The atmosphere is mostly carbon dioxide, which is denser than Earth's air, so the pressures at the surface are immense.  (It's the density and composition of the atmosphere that's why early photographs taken by probes on Venus's surface looked warped, as if the probe were sitting at the base of a bowl; the refraction of what light makes it to the surface caused optical distortion.)  If being inside a pressure cooker isn't bad enough, its dense clouds are largely composed of sulfuric acid.

As Sagan himself said, "Venus is very much like hell."

But Sagan was an amazingly creative thinker, and he came up with a proposal for reworking the atmosphere and, possibly, making it livable for Earthlings.  He suggested detonating a rocket carrying a cargo of cyanobacteria in its upper atmosphere, dispersing them into the clouds.  Cyanobacteria are primitive photosynthetic single-celled life forms, and Sagan's idea was that the updrafts would keep at least some of them aloft.  As they tumbled about in the (relatively) temperate clouds, they'd photosynthesize, consuming some of the atmosphere's carbon dioxide and releasing oxygen gas as a waste product.

The idea is that the aerial microbes would multiply, and although some would inevitably sink low enough to fry, enough would stay up in the clouds to steadily drop the carbon dioxide content of the atmosphere.  Less carbon dioxide, less greenhouse effect; less greenhouse effect, lower temperature.  Once the cloud temperature dropped below 100 C, water vapor would condense, and it would rain out the sulfuric acid.

Far-fetched, perhaps, especially for its time.  But it was an exciting enough proposal that I recall discussing it eagerly with my college friends and fellow science nerds.

This all comes up because of a peculiar observation of Venus made recently, by teams at the Center for Astronomy and Astrophysics at the Technical University of Berlin, the University of Wisconsin-Madison, and the Japan Aerospace Exploration Agency.  What they've seen is that there are clouds of "unknown absorbers" darkening the upper atmosphere of the planet in patches -- enough to affect the weather.

A composite image of theVenus, using data from the Japanese probe Akatsuki.  [Image courtesy of the Institute of Space and Astronautical Science/Japan Aerospace Exploration Agency]

And there are astronomers who think these "unknown absorbers" are not the products of exotic Venusian chemical reactions -- but are airborne single-celled life forms.

"It is hard to conceive of what would cause a change in the [planet's] albedo without a change in the absorbers," said Sanjay Limaye, planetary scientist at the University of Wisconsin-Madison and co-author of a paper last week in The Astronomical Journal that seriously considered the possibility of the absorbers being life forms.  "Since there are few species which have physical, chemical and spectral properties that are consistent with the composition of the Venus clouds, they may have evolved independently on Venus."

The researchers are up front that extraterrestrial microbes are just one possible explanation of the peculiar darkening of the skies, which occurs with an odd periodicity along with an overall decrease in albedo since measurements started in 2006.  It may turn out to be simply a chemical reaction -- still the most likely explanation for the gas output from search-for-life experiments by the Mars landers -- but the fact that scientists are even considering the microbe hypothesis is encouraging and exciting.

Whichever it turns out to be, it seems fitting to end with another quote by Sagan: "Somewhere, something incredible is waiting to be known."

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This week's Skeptophilia book recommendation is a classic: James Loewen's Lies My Teacher Told Me.  Loewen's work is an indictment not specifically of the educational system, but of our culture's determination to sanitize our own history and present our historical figures as if they were pristine pillars of virtue.

The reality is -- as reality always is -- more complex and more interesting.  The leaders of the past were human, and ran the gamut of praiseworthiness.  Some had their sordid sides.  Some were a strange mix of admirable and reprehensible.  But what is certain is that we're not doing our children, nor ourselves, any favors by rewriting history to make America and Americans look faultless.  We owe our citizens the duty of being honest, even about the parts of history that we'd rather not admit to.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Planetary genesis

In yesterday's post, I looked at some new photographs from the Hubble Space Telescope of one of the oddest objects in the universe -- the luminous blue variable Eta Carinae.  But that's not the only stunning new research coming from the astrophysicists.  No less than three studies in the last month have given us a new lens into something that has stirred our imaginations for years -- the characteristics of exoplanets.

The number of exoplanets -- planets around other stars -- has grown steadily since the first one was confirmed in 1995.  Today there are over four thousand exoplanets that have been discovered, and they include every possible twist on size and temperature, from "hot Jupiters" (gas giants that orbit so near their parent star that they complete one revolution in only a few days, and are so hot that they could liquify iron) to cool, rocky worlds like our own, to frozen blobs of methane and ammonia like Uranus and Neptune.  In fact, every time we find new worlds, it seems to open up new possibilities about what could be out there.

Let's start with a study that appeared in Nature Astronomy last week, led by Björn Benneke of the University of Montreal, which found a planet in that mid-range mass that doesn't exist in our Solar System -- a "sub-Neptune" or "super-Earth" that's somewhere between the mass of the Earth and the mass of Neptune (seventeen times Earth's mass).

What is extraordinary about this study is that the astronomers who studied this planet were able to determine the nature of its atmosphere from a hundred light years away.  The planet goes by the euphonious name GJ3470b, and its composition was unexpected.  Instead of being enriched in (relatively) heavy gases like methane and ammonia, like the gas giants in our own system, it was made almost entirely of the lightweight gases hydrogen and helium.  It also is so close to its parent star that it completes one revolution in only three days, so it's surprising that its proximity didn't result in the radiation and heat blowing away all of the lighter gases (which is apparently what happened to the inner planets in the Solar System), even considering that the star is a relatively dim red dwarf.

"We expected an atmosphere strongly enriched in heavier elements like oxygen and carbon which are forming abundant water vapor and methane gas, similar to what we see on Neptune," Benneke said in a press release.  "Instead, we found an atmosphere that is so poor in heavy elements that its composition resembles the hydrogen- and helium-rich composition of the Sun."

This brings up lots of questions about why planets have the atmospheres they have -- a relatively new field from which we are only beginning to have enough data to form some tentative hypotheses.

This brings us to the second study, also in Nature Astronomy, published last month and authored by a team led by Sebastiaan Haffert of the Leiden Observatory.  This team studied PDS70, a relatively young star that's 370 light years away, which is currently in the process of forming planets.  What's the coolest about this one is that we're able to observe the planets developing an atmosphere by siphoning off material from the outer layers of the star.

The authors write:

Newly forming protoplanets are expected to create cavities and substructures in young, gas-rich protoplanetary disks, but they are difficult to detect as they could be confused with disk features affected by advanced image analysis techniques.  Recently, a planet was discovered inside the gap of the transitional disk of the T Tauri star PDS 70.  Here, we report on the detection of strong Hα emission from two distinct locations in the PDS 70 system, one corresponding to the previously discovered planet PDS 70 b, which confirms the earlier Hα detection, and another located close to the outer edge of the gap, coinciding with a previously identified bright dust spot in the disk and with a small opening in a ring of molecular emission.  We identify this second Hα peak as a second protoplanet in the PDS 70 system. The Hα emission spectra of both protoplanets indicate ongoing accretion onto the protoplanets, which appear to be near a 2:1 mean motion resonance...  Finding more young planetary systems in mean motion resonance would give credibility to the Grand Tack hypothesis in which Jupiter and Saturn migrated in a resonance orbit during the early formation period of our Solar System.

Taking a step even further back into planet development, the third study, which appeared in Astrophysical Journal Letters in June, a team led by Takashi Tsukagoshi of the National Astronomical Observatory of Japan found a star that is in the early stages of planetary condensation from the "accretion disc" of dust and gas surrounding a young star.  The star, TW Hydrae, is two hundred light years from Earth, and the forming planet is currently a huge blob of luminescent gas whose diameter is about the distance from the Sun to Jupiter.  (The blob is located at a distance from TW Hydrae about equal to the orbit of Neptune.)

Cooler still is they have photographs:

[Image courtesy of the ALMA Radio Array and the National Astronomical Observatory of Japan]

The current supposition is that the blob will eventually condense into a gas giant about the size of Neptune.

The speed with which we're finding out new information about the formation of stars and planets further reinforces my general impression that exoplanet systems like our own are so common out there as to be nearly ubiquitous.  This, of course, further improves the likelihood that at least some of those planets host life.  Some of it, perhaps, intelligent.  Scientists are currently trying to figure out how to detect "biosignatures" on other planets, and it's harder than you'd think; consider that until a hundred years ago, our Earth would have been "radio silent" and therefore nearly invisible to alien astronomers except by the curious abundance of elemental oxygen in our atmosphere.  (Oxygen is so reactive that if there weren't processes continually pumping it into the atmosphere -- photosynthesis, in our case -- it would all eventually get locked up in stable molecules like carbon dioxide and silicon dioxide.)

So keep your eye on the skies.  When you look at the stars at night, consider that many -- probably most -- of the stars you're looking at have their own planetary systems.  And maybe, just maybe, there is an extraterrestrial out there contemplating the skies over its own home world who is looking back at you.

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This week's Skeptophilia book recommendation is pure fun for anyone who (like me) appreciates both plants and an occasional nice cocktail -- The Drunken Botanist by Amy Stewart.  Most of the things we drink (both alcohol-containing and not) come from plants, and Stewart takes a look at some of the plants that have provided us with bar staples -- from the obvious, like grapes (wine), barley (beer), and agave (tequila), to the obscure, like gentian (angostura bitters) and hyssop (Bénédictine).

It's not a scientific tome, more a bit of light reading for anyone who wants to know more about what they're imbibing.  So learn a little about what's behind the bar -- and along the way, a little history and botany as well.

[Note: if you purchase this book using the image/link below, part of the proceeds goes to support Skeptophilia!]

Piercing the clouds

One of the most unusual stories that H. P. Lovecraft ever wrote is "In the Walls of Eryx."  It isn't the usual soul-sucking eldritch nightmares from the bubbling chaos at the center of the universe; in fact, it's his only real science fiction story.  It centers around a human colony on Venus, devoted to mining a kind of crystal that can be used for propulsion.  There's an intelligent native species -- reptilian in appearance -- who was content to let the humans bump around in their space suits (Lovecraft at least got right that the atmosphere would be toxic to humans) until the humans started killing them.  At that point, they started fighting back -- and setting traps.

The story centers around a crystal hunter who is out on an expedition and sees a huge crystal in the hands of a (human) skeleton.  He goes toward it, and bumps into an unseen obstacle -- completely transparent walls, slick (and therefore unclimbable) and twelve feet tall (so unjumpable).  The problem is, when he tries to back out, he's already moved around a bit, and doesn't retrace his steps perfectly.

Then he runs into another wall.

What's happened is that he's stumbled into an invisible labyrinth.  And how do you find your way out of a maze if you can't see it?  You'll just have to read it.  It's only a dozen or so pages long, and is one of the neatest (and darkest) puzzle-box stories you'll ever pick up.

It's been known since Lovecraft's time ("In the Walls of Eryx" was written in 1936) that Venus was covered by clouds, and its surface was invisible from Earth.  Of course, a solid mantle of clouds creates a mystery about what's underneath, and speculation ran wild.  We have Lovecraft's partially-correct solution -- a dense, toxic atmosphere.  Carl Sagan amusingly summed up some of the early thinking on Venus in the episode "Heaven and Hell" from his groundbreaking series Cosmos: "I can't see a thing on the surface of Venus.  Why not?  Because it's covered with a dense layer of clouds.  Well, what are clouds made of?  Water, of course.  Therefore, Venus must have an awful lot of water on it.  Therefore, the surface must be wet.  Well, if the surface is wet, it's probably a swamp.  If there's a swamp, there's ferns.  If there's ferns, maybe there's even dinosaurs...  Observation: I can't see anything.  Conclusion: dinosaurs."

Of course, reputable scientists didn't jump to these kinds of crazy pseudo-inferences.  As Neil deGrasse Tyson points out, "If you don't know, then that's where your conversation should stop.  You don't then say that it must be anything."  (Perhaps not a coincidence that Tyson was the host of the reboot of Cosmos that appeared two years ago.)

The first hint that Venus was not some lush tropical rain forest came in the late 1950s, when it was discovered that there was electromagnetic radiation coming from Venus that only made sense if the surface was extremely hot -- far higher than the boiling point of water.  This was confirmed when the Soviet probe Venera 9 landed on the surface, and survived for 127 minutes before its internal circuitry fried.

In fact, saying it's "hot" is an understatement of significant proportions.  The average surface temperature is 450 C -- 350 degrees higher than the boiling point of water, and hot enough to melt lead.  The atmosphere is 96.5% carbon dioxide (compared to 0.04% in the Earth's atmosphere), causing a runaway greenhouse effect.  Most of the other 3.5% is nitrogen, water vapor, and sulfur dioxide -- the latter being the rotten-egg chemical that, when mixed with water, creates sulfuric acid.

Yeah.  Not such a hospitable place.  Even for crystal-loving intelligent reptiles.

Photograph from the surface of Venus [Image is in the Public Domain, courtesy of NASA/JPL]

But there's still a lot we don't know about it, which is why at the meeting last fall of the American Geophysical Union, there was a proposal to send a probe to our nearest neighbor.  But this was a probe with a difference; it would be attached to a balloon, which would keep it aloft, perhaps indefinitely given the planet's horrific convection currents.  From there, we could not only get photographs, but more accurate data on the atmospheric chemistry, and possibly another thing as well.

One of the things we don't know much about is the tectonics of the planet's surface.  There are clearly a lot of volcanoes -- unsurprising given how hot it is from other causes -- but whether the crust is shifting around the way it does on Earth is not known.  One way to find out would be looking for "venusquakes" -- signs that the crust was unstable.  But how to find that out when probes on the surface either melt or get dissolved by the superheated sulfuric acid?

The cool suggestion was that because of the atmosphere's density, it might be "coupled" to the surface.  So if something shook the surface -- a venusquake or volcanic eruption -- those waves might be transferred to the atmosphere.  (This effect is insignificant on Earth because our atmosphere is far, far less dense.)  Think of a plate with a slab of jello on it -- if you shake the plate, the vibrations are transferred into the jello because the whole thing is more or less stuck together, so the surface of the jello wobbles in resonance.

An airborne probe might be able to tell us something about Venus's geology, which is pretty awesome.  It appeals not only to my fascination with astronomy, but my love of a good mystery, which the second planet definitely is.

So I hope this project gets off the ground, both literally and figuratively.  Even if it's unlikely to detect anything living -- reptilian or not -- we could learn a great deal about what happens when the carbon dioxide levels start undergoing a positive feedback.

A scenario we all would like very much not to repeat here at home.

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This week's Skeptophilia book recommendation is a tour-de-force for anyone who is interested in biology -- Richard Dawkins's The Ancestor's Tale.  Dawkins uses the metaphoric framework of The Canterbury Tales to take a walk back into the past, where various travelers meet up along the way and tell their stories.  He starts with humans -- although takes great pains to emphasize that this is an arbitrary and anthropocentric choice -- and shows how other lineages meet up with ours.  First the great apes, then the monkeys, then gibbons, then lemurs, then various other mammals -- and on and on back until we reach LUCA, the "last universal common ancestor" to all life on Earth.

Dawkins's signature lucid, conversational style makes this anything but a dry read, but you will come away with a far deeper understanding of the interrelationships of our fellow Earthlings, and a greater appreciation for how powerful the evolutionary model actually is.  If I had to recommend one and only one book on the subject of biology for any science-minded person to read, The Ancestor's Tale would be it.

[If you purchase the book from Amazon using the image/link below, part of the proceeds goes to supporting Skeptophilia!]

The turning of the tides

It's tempting to think that conditions on Earth have always been like they are now.

On one level, we know they weren't.  When people picture the time of the dinosaurs, it usually comes along with images of swamps and ferns and rain forests.  (And volcanoes.  Most of the kids' books about dinosaurs illustrate them as living near erupting volcanoes, which seems like a poor choice of habitat.)

But the basics -- the air, water, soil, and so on -- we picture as static.  It's been the basis of hundreds of science fiction stories; people go back into the distant past, and although there are (depending on when exactly they went to) often giant animals who want to eat you, you have no problem breathing or finding food.

I had a neat hole punched in that perception last week when I read Peter D. Ward's book Out of Thin Air.

 

Ward is a paleontologist at the University of Washington, and his contention -- which is well-argued and supported by a wealth of evidence -- is that the oxygen content of the atmosphere has varied.  A lot.  It's at about 21% at sea level now, but hit a staggering low of 13% immediately after the Permian-Triassic extinction, comparable on today's Earth to being at an altitude of 12,500 feet (think the High Andes).  Humans time-traveling back then would have a seriously difficult time breathing, and life was probably confined to areas that were near sea level -- and those areas would be completely isolated from each other by higher ground in between where there was not enough oxygen to survive.

There were times when it was much higher, too.  Ward says in the late Carboniferous Era, the oxygen content suddenly spiked to around 30%, which explains why coal formation stopped; at 30% oxygen, dead plant matter will combust with little encouragement, resulting in little left behind to form coal seams.

If you'd like to find out more, I highly recommend Ward's book, which is not only an argument for the fluctuating-atmosphere model, but is a good overview of the major events in Earth's history.

Parasaurolophus skeleton [image courtesy of the Wikimedia Commons]

I had another blow delivered to the static-Earth perception from a study that was published last week in Geophysical Research Letters, called "Is There a Tectonically Driven Super‐Tidal Cycle?", by Mattias Green, J. L. Molloy, H. S. Davies, and J. C. Duarte, which considered the possibility that even the tides haven't always been as they are today.

What their study did was to look at a model of the dispersal of tidal energy, and they found that when all the continents were joined into a single land mass (Pangaea), which last happened at the end of the Permian Era a little over 250 million years ago, it represented a tidal energy minimum.  This meant that the tides were smaller than today, and that the majority of the (single) ocean was effectively a stagnant pool of water, with little vertical mixing of nutrients.  Stagnant, low-nutrient, low-oxygen water generally has little biodiversity -- a few species that can tolerate such conditions do exceptionally well, but the rest die out.  So this could be yet another reason that the cataclysmic Permian-Triassic Extinction happened, in which (by some estimates) 90% of the species on Earth became extinct.

What the Green et al. study suggests is that we're near a tidal maximum.  As the press release about the study put it:

In the new study, scientists simulated the movement of Earth’s tectonic plates and changes in the resonance of ocean basins over millions of years. 

The new research suggests the Atlantic Ocean is currently resonant, causing the ocean’s tides to approach maximum energy levels.  Over the next 50 million years, tides in the North Atlantic and Pacific oceans will come closer to resonance and grow stronger.  In that time, Asia will split, creating a new ocean basin... 

In 100 million years, the Indian Ocean, Pacific Ocean and a newly formed Pan-Asian Ocean will see higher resonance and stronger tides as well.  Australia will move north to join the lower half of Asia, as all the continents slowly begin to coalesce into a single landmass in the northern hemisphere... 

After 150 million years, tidal energy begins to decline as Earth’s landmasses form the next supercontinent and resonance declines.  In 250 million years, the new supercontinent will have formed, bringing in an age of low resonance, leading to low tidal energy and a largely quiet sea, according to the new research.

It's a little humbling to think about, isn't it?  The processes that shape the continents, drive the tides, control the chemistry of the atmosphere, will keep chugging along long after we're a paleontological footnote in the textbooks of our far distant descendants.  It's not that what we're doing now isn't critical; in the short term, the out-of-control fossil fuel burning is doing things to our atmosphere that will certainly cause us grievous harm, not to mention the short-sighted pollution of the very resources we depend on.

But if we do succeed in wiping ourselves out, which lately has seemed increasingly likely, the processes that govern the Earth will keep on going without us.  So will natural selection; the survivors of the current mass extinction will evolve into other "forms most beautiful and most wonderful," as Darwin put it in The Origin of Species.

Not that this will be much consolation to us, of course.  But I do find it comforting, in a strange way.  However important we think we are, on the scale of the natural world, we're pretty tiny.  Whatever damage we do, eventually the Earth will recover, with or without us.  And the atmospheric, geological, and tidal ups and downs will continue -- world without end, amen.