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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Violent moon

If I had to vote for the single weirdest place in the Solar System, my choice would be Jupiter's moon Io.

Io is the innermost and third-largest of the "Galilean moons" of Jupiter, the ones that caused so much trouble for poor Galileo Galilei when he observed them in 1610 and informed the Catholic Church powers-that-be that we aren't the center of the universe.  It wasn't until the Voyager flybys in the late 1970s that we could see it as anything more than a fuzzy dot, even in the largest telescopes; the first close-up photographs invited comparisons to a moldy pizza,  Detailed photos from the Galileo probe in 1999 confirmed the original assessment: Io is one bizarre place.

1999 photograph of Io from the Galileo probe [Image is in the Public Domain courtesy of NASA/JPL]

The first weird thing about it is that it is the most tectonically active place in the Solar System.  Those pock-marks on the surface aren't impact craters, they're volcanoes.  In general, the smaller a body is, the less tectonically-active you might expect it to be.  Tectonic activity is (usually) triggered by convective fluid motion in a molten mantle or core, which requires a very hot interior to keep it going.  The heat comes from two sources; the energy released by its coalescence during its formation, and the decay of radioactive elements in its interior.  If that heat radiates away faster than it's being released, eventually the body cools off and freezes, and (most) tectonic activity stops.  Heat dissipates more rapidly from a small object, so they tend to shut down much sooner.  (That's what happened to the Moon, for example.)

But despite Io's small size, something is keeping it hot enough to create hundreds of active volcanoes.  But what?

It turns out it's the proximity to Jupiter.  The giant planet's gravitational pull creates significant tidal forces, and the stretching and compressing Io experiences generates enough friction in the moon's interior to keep the insides molten.  The result: violent volcanic activity that spews liquid sulfur jets into the sky, creating plumes as much as five hundred kilometers in height.  (It's the sulfur that's responsible for Io's bright colors.)

In fact, Io actually ejects so much material from its volcanoes that it has created a plasma torus around Jupiter in its wake -- a donut-shaped ring of charged particles tracing out its orbit.

Another cool thing about Io is that it's in orbital resonance with two of the other Galilean moons, Europa and Ganymede.  Io is the innermost, and has an orbital period exactly twice as fast as Europa and four times as fast as Ganymede -- a stable configuration that has since been found in other systems with multiple moons.  So every fourth revolution of Io, all three line up perfectly!

The reason this comes up is a new study out of Caltech that has found data suggesting an enormous underground magma ocean inside Io -- planetary scientists David Stevenson and Yoshinori Miyazaki believe the presence of a hundred-kilometer-thick liquid mantle explains the extremely active surface and its anomalous magnetic field, another feature Io shares with few other small bodies in the Solar System.

What lies deeper than the mantle is unknown.  Some astrophysicists believe it has a metallic core, but that question is far from settled.

What's certain is that Io is a peculiar place -- sulfur volcanoes, seething lava lakes on the surface, continuous "moonquakes" caused by the tidal forces exerted by the enormous planet Jupiter looming overhead.  And like anything odd and unexpected, it will continue to attract the attention of scientists, and we will continue to be astonished at what we learn about one of the weirdest places in our neighborhood.

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The dunes of Io

By anyone's standards, Jupiter's moon Io is a strange place.  It is by far the most geologically-active body in the Solar System, which is extremely unusual for an object its size.  Since tectonic forces are created by heat generated in the core, and smaller objects radiate away heat faster, it was thought that most planetary moons should be tectonically dead -- essentially, frozen in place.

What keeps the fires in Io going are the tidal forces between Jupiter and the other three "Galilean" moons (so called because they were first spotted by Galileo Galilei in January of 1610, and were instrumental in his championing of the heliocentric model of the Solar System).  But from earthbound telescopes all four just looked like points of light, despite the fact that as moons go, they're pretty big.  In fact, the largest of them -- Ganymede -- is bigger than Mercury, with a radius of 2,634 kilometers (as compared to Mercury's 2,440).  The four, the two aforementioned plus Europa and Callisto, were all named for various of Zeus's lovers, which meant astronomers had an extensive list of names to choose from, given that 95% of Greek mythology was driven by Zeus's inability to keep his toga on.

In any case, the push-and-pull of the gravitational forces from Jupiter and its moons stretches Io, and the friction thus created generates enough heat to keep its core (thought to be made mostly of iron, like Earth's) molten.  This thermal energy drives tectonic forces that dwarf the most violent volcanoes and earthquakes here on our planet.  Io has extensive lava flows, some over five hundred kilometers across.  Its volcanoes have ejected so much debris that there is a plasma ring surrounding Jupiter, sketching out Io's orbit.

We got our first good images of Io from Voyager 1 and Voyager 2 in 1979, and from its brightly-colored, pockmarked surface astronomers said it "looked like a moldy pizza" -- a vivid image that is certainly apt enough:

An image of Io taken, appropriately enough, by the spacecraft Galileo in 1995 [Image is in the Public Domain courtesy of NASA/JPL]

The bright yellows and oranges come from crystalline sulfur, which is abundant on the moon's surface.  Also common on its surface is sulfur dioxide, which at Earth's surface temperatures is a colorless gas that smells like rotten eggs; at Io's temperatures, averaging at 110 K (about -160 C), it's a crystalline solid.  The rest is mostly made up of silicate rock and sand.

There's still a lot we don't know about this peculiar place.  One of its odd features is that it has dunes, some of them over thirty meters high.  This should be impossible, as dunes are caused by fluid flow -- on Earth, either wind or water -- and Io has essentially no atmosphere and no liquid component of any kind on the surface.  But a recent paper published in Nature Communications explains a way that dunes can form without any wind; once again, it's caused by Io's extreme volcanism.  The study found that if there's at least a ten-centimeter thick layer of sulfur dioxide ice, and it is contacted by the subterranean (well, subionion) lava flows, the ice sublimates rapidly and explosively, blowing plumes of gas and debris at speeds of up to seventy kilometers and hour, reaching as much as two hundred kilometers high.

The force, though, isn't just exerted upwards, it's exerted outward.  This lateral blast moves enough of the sand and rock on the surface to generate Io's extensive dunes.  A combination of two things -- Io's low gravity and lack of an atmosphere -- means that the airborne debris can move a lot farther than a similar flow could do on Earth.  So while at first glance the processes seem similar to what we know of planetary geology, it's (as far as we know) unique in the Solar System.

"In some sense, these [other worlds] are looking more familiar," says George McDonald, a planetary scientist at Rutgers University, who co-authored the study, in an interview with Science News.  "But the more you think about it, they feel more and more exotic."

If you want to experience mystery and wonder, just look up.  The night sky is filled with a myriad places we are only just beginning to understand.  As French physicist and mathematician Jules Henri Poincaré put it, "Astronomy is useful because it raises us above ourselves; it is useful because it is grand; …  It shows us how small is man's body, how great his mind, since his intelligence can embrace the whole of this dazzling immensity, where his body is only an obscure point, and enjoy its silent harmony."

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The oceans of Europa

On Monday, we looked at some new techniques for detecting exoplanets, and how exciting that is for people like me who are obsessed with extraterrestrial life.  The difficulty, of course, is that even if you find a thousand Earth-like planets in the habitable zone, how could you tell if they're inhabited?  Consider how long the Earth has hosted life (on the order of three billion years) and how long it's been that we've had living things that would be detectible to distant aliens via such signals as radio and television transmissions (on the order of a hundred years).

Life has been present on Earth thirty million times longer than it would be easily detectible to a technological species in another stellar system.

So life could be more or less everywhere out there.  But how could we find it?

The possibilities are limited.  There's been a suggestion that one way is to analyze the atmosphere and look for chemicals like oxygen that are highly reactive and probably wouldn't persist unless there was something (i.e. something living) pumping it in at a constant rate.  But finding planets at a distance is one thing, and analyzing the atmosphere of those planets from something like the faint absorption spectrum lines of the light reflected from the surface, is another thing entirely.

So unless we stumble across a technological society whose signals (deliberate or otherwise) we detect, we could be looking at stupendous biodiversity and never know it.

A different approach is to look for life closer to home.  One of the goals of the Mars rover expeditions was to analyze the soil for the presence of bacterial metabolism, the results of which were equivocal at best.  Venus is out, unless there are life forms that enjoy being in an acidic pressure cooker, which seems unlikely.

But what about the outer planets?

If there is life on the gas giants themselves, it'd have to be unlike anything we have here on Earth.  Carl Sagan hypothesized giant "floaters," creatures like enormous parachutes, that would ride the stormy updrafts of the thick atmosphere and metabolize the methane that makes up a good percentage of it.  But what about the moons?

The moons of the gas giants are possible candidates, as they're small and rocky, and at least some of the larger ones have a stable atmosphere.  The problem is, they're cold.  Ganymede, for example, Jupiter's largest satellite, has a mean surface temperature of about -160 C.

Not exactly your next tropical vacation spot.

But it's not as hopeless as all that, because there's more going on here than meets the eye.  Which brings me to Jupiter's moon Europa.

Europa, showing the cracks in the ice sheet colored by what may be a mix of minerals and organic compounds from the subsurface liquid water ocean [Image is in the Public Domain courtesy of NASA/JPL]

Europa is the smallest of the four "Galilean" moons, so called because they were first observed by Galileo Galilei, which led him afoul of the powers-that-be when he claimed they were orbiting Jupiter (Earth, remember, was thought to be the center of the universe, with everything orbiting around it).  But eppur si muove, as Galileo muttered when he was found guilty of heresy ("and yet it moves"), and the total number of Jovian satellites now stands at 79.

Europa, however, is especially fascinating.  Pioneer 10 and 11, the (aptly-named) Galileo orbiter, and most recently the New Horizons probe, have all brought us back a picture of Europa that's curious to say the least.  It's got a surface made mostly of water ice, but its overall density is consistent with being mostly composed of silicate minerals (so it's a rocky ball underneath its icy covering).  Most interesting, though, is that magnetometer readings support the conclusion that between the two is a layer of ion-rich liquid water on the order of thirty kilometers in depth -- a subsurface sea rich in magnesium, sodium, and calcium, traces of which are found on the surface when the cracking of shifting of the ice sheet allows the seawater to bubble up and freeze onto the surface.

This makes Europa an excellent candidate for hosting life, at least the microbial type.  But what's keeping the water liquid, so far out there in the cold reaches of the Solar System?

Apparently, its host planet is.  Jupiter is enormous, and has Europa tidally locked (the same side faces Jupiter all the time).  Its orbit isn't perfectly circular, though, and as it zips around, tracing out an ellipse, the changes in gravitational pull generate tidal flexing.  The giant planet pulls and distorts the core of the moon, and the friction that creates generates enough heat to keep the subsurface ocean liquid.

So we have something a little analogous to the Earth's hydrothermal vents, albeit powered by a different process.  It means that (though it saddens me to admit) it's probably better to put our money into sending a surface probe to Europa, to look for traces of life frozen onto the surface, than scanning the skies looking for life outside of the Solar System.

We could do both, of course.  That'd make me happy.  But given the budget cuts to NASA in the last few years, they've got to put their time, effort, and money into whatever is going to have the greatest likelihood of working.  At the moment, that looks like the search for extraterrestrial life should focus on our own neighborhood -- starting with a moon that initially looked like a lifeless ball of ice.

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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.

In the dark

In this line of business, it's all too common to run into something so stupid that at first, you think it's a joke.  No one, you think, no one could possibly be that gullible and/or ignorant of science.

And then you look into it, and you find that, lo and behold, (1) it's not a joke, (2) there are in fact people that gullible and ignorant, and (3) it really freakin' hurts when you do a faceplant into your computer keyboard.

This was my experience when a friend and loyal reader of Skeptophilia sent me a link a couple of days ago entitled, "NASA Confirms Earth Will Experience 15 Days of Darkness in November 2017."  This article, by one David Vanallen, appeared on the site Reflection of Mind earlier this year, and warns us that in a couple of months, we're gonna be in for some serious shit.

He doesn't put it quite that way, however.  Here's a capsule summary of what Vanallen says NASA has "confirmed:"

1. This November, Jupiter and Venus will come into "close proximity" of each other, being separated in the sky by a distance of only one degree.
2. Venus will, at that point, be shining at ten times the luminance that Jupiter is.
3. The bright light from Venus will heat Jupiter's gaseous surface, causing it to launch an "absurdly high amount of hydrogen" into space.
4. Said hydrogen will fall directly into the Sun, arriving there at precisely 2:50 AM on November 15.
5. The additional hydrogen will cause a thermonuclear detonation to occur on the Sun's surface, raising its temperature to 9,000 C, and turning the Sun's color to a "bluish shade."
6. This will cause the Sun to appear dimmer from the Earth.  
7. The effect will last until precisely 4:45 on November 30, at which point the Sun will return to normal.

That scary stuff notwithstanding, former NASA director Charles Bolden said we shouldn't be worried.  All that's going to happen, Bolden said, is a huge increase in the Earth's average temperature:

We do not expect any major effects from the Blackout event.  The only effect this event will have on Earth is an increase of 6 – 8 degrees in temperature. the polar cap will be mostly affected by this.   No one should worry much.  This event would be similar to what Alaskans experience in the winter.

Okay, now, hang on a moment.

Jupiter and Venus won't be in "close proximity."  They will just appear that way because from Earth, they'll be kind of lined up in the sky.  This is like saying that as you're standing on a beach in California watching the Sun set over the Pacific Ocean, the ocean is in danger of boiling away because it's so much closer to the Sun than it was at noon.

Furthermore, if the luminance of Venus was high enough to cause major gaseous eruptions on Jupiter, it would fry us here on Earth.  Jupiter and Venus are an average of 750 million kilometers from each other; at its farthest, Venus is 260 million kilometers from Earth.  There's this thing called the inverse-square law that shows how all of this works, but my guess is that David Vanallen never got past 8th grade physical science, so maybe he's never heard of it.

In any case, the reason Venus is brighter than Jupiter has nothing to do with its being hotter (although it is, in fact, by a large margin).  Venus is just closer to the Sun.  End of story.

[image courtesy of NASA]

As far as "absurd amounts of hydrogen" causing a thermonuclear explosion, well... the Sun is kind of one big thermonuclear explosion already.  Adding hydrogen, in however absurd amounts you like, wouldn't make much of a difference, especially given that Jupiter's radius is ten times smaller than the Sun's.  And that's the whole planet, not just some absurd hydrogen cloud it's jettisoned.

Then, the hydrogen is supposed to make the Sun heat up, which will make it dimmer, which will cause it to be dark here on Earth, which in 15 days will make the Earth's temperature rise by an amount that's four times the increase we've experienced from all of global warming put together, which will make the Arctic ice caps melt, but we shouldn't worry about it.

Because all of that is "just like Alaska in winter."

To which I just have one thing to say: What the actual fuck?

Oh, and I doubt highly that Charles Bolden, who is not only a pretty smart guy but has a B.S. in electrical engineering and a M.S. in systems management, had anything to do with any of this.

What makes me facepalm the worst about all of this is that there are dozens of sites now reprinting this story pretty much verbatim, and none of the ones I looked at added, "... and anyone who believes this must have their skull filled with dust bunnies, cobwebs, and dead insects."  All of the ones I saw were posting it because, apparently, they believe that it's true.  And one of them had been shared, tweeted, and reposted over 10,000 times.

Which just goes to show that if you append "NASA officials confirm" in front of damn near anything, you can get people to believe it.  Oh, and that reminds me: I should warn you that NASA officials have confirmed that today's solar eclipse is going to cause the Earth's magnetic poles to flip, which will mean all clocks will start running backwards, which will reverse the polarity in your DNA's quantum frequency vibrations, meaning you'll start to age backwards.  Tomorrow morning, we're all going to wake up feeling younger, stronger, and healthier, which would be cool except for the fact that it will also make our neurons run in reverse, so we'll remember the future and have no idea about the past.

I'd say "remember, you heard it here first," but the last part kind of makes that impossible.  Oh, well.   Sic transit gloria mundi.

All I want for Christmas is a Death Asteroid

So it's December, which means it's time for Peace on Earth, Good Will Toward Our Fellow Humans, and Death Asteroids.

I'm not sure what it is about this time of year that brings out the fatalism in so many.  You might recall that the Mayan Apocalypse, for example, was scheduled on December 21, 2012, prompting mass panic amongst the woo-woos until December 22 rolled around and it became apparent that contrary to popular expectation, the world had failed to end on schedule.

It's disappointing when you can't even count on an apocalypse to show up on time.

In any case, this year, the End of the World is going to be brought about by an asteroid with the euphonious name 2003 SD220, which is scheduled to make a near pass to Earth on Christmas Eve.

2003 SD220 [image courtesy of JPL]

Well, near, that is, in the sense of "11 million kilometers away," which is 28 times the distance from the Earth to the Moon.  So we're talking "near" in the astronomical sense, just as geologists consider anything under about 50,000 years old "recent," even though 50,000 years seems like a long time even for someone as old as I am.  But such sensible and soothing words have not had the least effect on the woo-woos, who are jumping about making panicked little squeaking noises about how the asteroid is going to kill us all, notwithstanding the fact that all of the previous Ends of the World they predicted have not, technically, happened.

The asteroid is 2.5 kilometers across and is moving five miles per second, which is a pretty good clip for something that large.  But from there, irrational fear takes over and logic goes right out the window.  It will be close enough, we are told, that its gravitational pull will cause us to experience deadly tsunamis, earthquakes, and the eruption of dormant volcanoes.  And that's if it doesn't actually impact the Earth directly, which would be an "extinction-level event."

Never mind that there are plenty of mountains on the Earth that are 2.5 kilometers tall, and their gravitational pull doesn't cause tsunamis etc.  And they're a hell of a lot closer than 2003 SD220 will ever get.

But maybe it's because it's traveling so fast.  Maybe by some new and undiscovered type of physics, moving fast makes something's gravitational pull increase.  I dunno.

So NASA, who must be really fucking sick and tired of people who don't understand science getting everyone stirred up every couple of months, issued a statement.  Paul Chodas, manager of the Near-Earth Object Office of the Jet Propulsion Laboratory, said the following:

There is no scientific basis -- not one shred of evidence -- that an asteroid or any other celestial object will impact Earth on those dates. 

In fact, NASA's Near-Earth Object Observations Program says there have been no asteroids or comets observed that would impact Earth anytime in the foreseeable future.  All known Potentially Hazardous Asteroids have less than a 0.01% chance of impacting Earth in the next 100 years. 

The Near-Earth Object office at JPL is a key group involved with the international collaboration of astronomers and scientists who keep watch on the sky with their telescopes, looking for asteroids that could do harm to our planet and predicting their paths through space for the foreseeable future. If there were any observations on anything headed our way, we would know about it. 

If there were any object large enough to do that type of destruction... we would have seen something of it by now.

Can't you just hear the annoyed sighing that went along with his writing this?

But of course, that statement had exactly the opposite effect from what Chodas wanted.  If NASA was saying the asteroid is harmless, that must mean they're covering something up.  It must be deadly.  It must, in fact...

... be four times the size of Jupiter.

And yes, there are people who are seriously claiming that.

Why haven't we seen it yet, if it's so big, is something of a mystery.  After all, we can see Jupiter itself just fine, and it's currently 57,000 times further away than the asteroid is.

Maybe the asteroid is made of dark matter.  Makes as much sense as anything else these people say.

As for me, I'm not worried.  2003 SD220 is going to be far enough away that it won't be visible without a pretty good telescope, which is actually kind of disappointing.  So on Christmas Eve, I'll be nestled up all snug in my bed, and I sure as hell won't have visions of Death Asteroids dancing through my head.

Look before you leap

A friend and fellow Skeptophile sent a story to my attention on Facebook that seems fitting for the last Skeptophilia post of 2013.  It combines all of the essential elements: a claim that is so ridiculous that it clearly started as a hoax; a bunch of people (including folks in the media) who know so little science that they seem to have taken it seriously; a prediction that will have gullible individuals worldwide making complete fools of themselves next Saturday; and a Facebook back-and-forth that resulted in cheerful contributions from several loyal readers of this blog who were eager to get in on the fun of ripping the whole silly story to shreds.

The (recent) origin of the claim seems to have been this story in News Hound, entitled, "January 4, 2014 - Planetary Alignment Decreases Gravity - Float For Five Minutes!"  Here's what they're claiming:

It has been revealed by the British astronomer Patrick Moore that, on the morning of January 4th 2014,  an extraordinary astronomical event will occur. At exactly 9:47 am, the planet Pluto will pass directly behind Jupiter, in relation to the Earth. This rare alignment will mean that the combined gravitational force of the two planets would exert a stronger tidal pull, temporarily counteracting the Earth’s own gravity and making people weigh less. Moore calls this the Jovian-Plutonian Gravitational Effect.

And here we run into our first five problems with this claim:

First, 9:47 in which time zone?  You can see how that would make a difference.  I'm assuming that it's 9:47 Greenwich Mean Time, which would certainly be the most logical interpretation, but it'd have been nice if they'd specified.

Second, even if we do assume that it's 9:47 GMT, then only the point on the Earth that is angled away from the Sun, and thus toward Jupiter and Pluto, would experience the effect, given that the Earth is spherical.  The other side of the Earth would actually experience the opposite -- an additional pull of gravity (the Earth's plus Jupiter's plus Pluto's), and people in those regions would feel heavier and fall faster.  People elsewhere on the Earth would experience this as a sideward pull, and would thus be more likely to trip over curbs and fall down.

Third, why would it only last for five minutes?  In terms of apparent angular velocity, neither Jupiter nor Pluto is moving that fast.  You'd think we'd at least have a few weeks' worth of floating about the place until everything drifts out of alignment.

Fourth, we have a problem with magnitudes, here.  Jupiter is a big planet, yes, but at closest approach it is still very far away.  We had a whole kerfuffle over "planetary alignments" amongst the astrology crowd a couple of years ago, which prompted me to calculate the gravitational pull of Jupiter on the Earth, and I came out with one ten-millionth of a Newton, a force a hundred million times smaller than the force the Earth itself is exerting.  So there's no way that the pull of Jupiter will have any significant affect on your hang time, and Pluto would have even less.

Fifth, "British astronomer Patrick Moore" was indeed an authoritative figure in the world of astronomy, and for many years hosted BBC's popular show The Sky at Night.  The problem is, he's been dead for two years, so he's not revealing much of anything at the moment.

Patrick Moore and fellow astronomer Dr. Fiona Vincent [photograph courtesy of the Wikimedia Commons]

But all of this isn't stopping the author of the story on News Hound, who goes on to tell us:

Moore told scientists that they could experience the phenomenon by jumping in the air at the precise moment the alignment occurred. If they do so, he promised, they would experience a strange floating sensation.

Astronomers have long been aware that there would be an alignment of the planets on that date, when Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto would be on the same side of the Sun, within an arc 95 degrees wide. But now the effect could be expected as the gravitational effect of the other planets on the Earth’s crust is maximum even at their closest approach.

If you think you will be able to float around your house then you will be mistaken. BUT if you jump in the air at 9:47AM local time on January 4th 2014, it should take you about 3 seconds to land back on your feet instead of the usual 0.2 seconds.

We are then told to join in on Twitter, using the hashtag #ZeroGDay, which I definitely encourage all of you to do.

Okay, so here's the real scoop -- a discovery for which I thank my friend and loyal reader David Craig, who did some stellar research work on this whole ridiculous story.

Apparently, like so many crazy claims, this one does have a germ of truth to it.  Patrick Moore was a smart, clever, and exceptionally funny man, and on April 1, 1976, he played an April Fool's Day prank on his listeners by claiming that at -- guess when? -- precisely 9:47, Jupiter and Pluto would be in alignment, and if they jumped into the air, they'd feel weightless.  When the clock hit 9:47, Moore said, "Jump now!" -- and the telephone switchboard lit up with calls from listeners who said they'd felt the effect.  (In fact, one listener was furious because he said he'd jumped so high that he'd hit his head on the ceiling.)

So this story is apparently just the whole thing going around again, because, after all, if a practical joke works once, it can always be reused, right?   Evidently Patrick Moore thinks so.  He wasn't content with pranking people while he was alive, he's continuing to do it two years after his death.  Which he'd probably be pretty pleased about, and, honestly, is what I'll do if I have the opportunity.

Of course, I couldn't end this piece without some information on where the relevant planets actually are.  If you'll take a look at the Planetary Orbit Map from Lunaf.com, you'll see that the Earth, Jupiter, and Pluto are very far from alignment -- Earth and Jupiter are more-or-less in alignment, but Pluto is clear on the other side of the Sun.

So I encourage you to participate on Twitter in #ZeroGDay, but don't bother jumping up and down unless you are doing so for another reason, in which case you should have at it.

And this seems like a fitting place to end.  I am taking a brief vacation for the remainder of the week, so this will be my last post of 2013.  I will be back at it on Monday, January 6, 2014, however, so keep those suggestions and comments coming.  I wish you all a lovely New Year's Day, and that 2014 is everything you hope for!