The entire universe in blog form

Oct. 7 2014 7:30 AM

The Hidden Earth: Undersea Mountains by the Thousands

It’s not every day a new mountain is discovered. But then there’s the day you discover thousands of them.

As you might suspect, it’s hard to hide thousand-meter-high mountains anywhere on Earth … unless they’re hidden under thousands of meters of water.

And that’s just where these mountains are: Under the oceans, along the floor, where many modern mapping techniques can’t detect them. We’ve had ships using sonar crisscross the oceans for years, mapping the deep abyss, but as it turns out, oceans are big. There are vast regions the maps don’t cover, and in may places where they do the resolution isn’t detailed enough to spot these seamounts.

Enter satellites. Specifically, Cryosat-2 and JASON-1. Neither was designed to probe the depths of the seas—JASON-1 measures sea level rise, and Cryosat-2 measures the thickness of ice at the poles. But both use sophisticated techniques to map the surface topography (bumps and valleys) beneath them, and that’s what led to the discovery of these mountains.

The key factor: gravity. A mountain under the sea doesn’t have a lot of gravity, but it has some, and it pulls on the water’s surface above it. This can create an extra small bump in the ocean’s surface, which, though small, can be measured by the satellites. It’s incredibly detailed work; scientists analyzing the data have to account for tides, winds, waves, and more. But the satellites passed over the same regions over and again, smoothing out irregularities, leaving behind the signal of the mountains far beneath the waves.

That’s amazing. And the result is spectacular: Literally thousands of mountains, 1,000–2,000 meters high, discovered running across the length and width of the planet. It’s an entire category of our planet that we knew nothing about, and there it is, bang, ripe for the picking. And it doesn’t end there; these new data give more accurate results for seafloor depths, present new evidence for a previously unknown extinct (nonspreading) rift between Africa and South America, and reveal more information about how the Gulf of Mexico formed due to seafloor spreading.

And remember: The satellites weren’t designed to do this! Their data were stored and archived, and scientists went through them to make these astonishing discoveries.

Humanity has lived its entire span right here on Earth, and yet in many ways we know less about it than we do the Moon, or Mars. But as soon as we decided to leave it, to go above it, our knowledge of our home increased by leaps and bounds.

We have much of this planet left to explore … and it’s something we must do. You never know what you might find when you look around.

Video Advertisement

Oct. 6 2014 12:40 PM

Spot the Space Station This Week!

This week will have several excellent passes of the International Space Station over the United States, so whether you’ve seen it dozens of times, or never spotted it before, this is your big chance!

Since the ISS orbits about 400 kilometers above the Earth’s surface, where you see it depends on where you are. There are a lot of apps and websites that can give you your viewing information. I usually use—give it your latitude and longitude (or choose your location from a list) and it will give you times and maps of visible passes (as well as those of many other satellites).

Others include NASA’s Spot the Station, Astroviewer’s ISS observation site, ISS Tracker, and Space Weather’s Flyby page. There are so many apps for mobile devices it may be best to just tell you to search your platform’s store for them. If you have a favorite, tell everyone in the comments below!

spot the ISS
An example of a map generated by Heavens-Above. The path of ISS is labeled as well as bright stars, constellations, directions, and times.

Diagram by Heavens-Above

Also, if you’re more techy-minded, you can get the ISS Above device, which lights up when the station is about to pass; it’s very cool, but it’s probably a wee bit late to get one for this week’s passes. Still, it’s fun and quite cool.

I really enjoy just going outside and watching the station move through the sky, but it’s also pretty rewarding to try to photograph it as well. I’ve written about it before.

If you have good equipment and perseverance, you can capture it through a telescope as well. No one is better at this than Thierry Legault, who seemingly routinely captures jaw-dropping photos and video of the ISS. Over the weekend he posted this astonishing video of it transiting the Sun:

Legault is a master. Not only that, he’s now literally written the book on astrophotography! Called Astrophotography, it’s a fantastic guide on taking pictures and video of the sky. It has a lot of information on what equipment to use, how cameras work, and details on the actual steps of taking the pictures and how to process them afterward. It’s an excellent read, worth it just for the pictures. Whether you’re just starting out taking shots of the sky, or you have lots of experience, this book should be within arm’s reach. I learned quite a bit from it, and I’m itching to try some of his techniques out.

Mind you, the holidays are coming up soon, too. I bet this would make a well-appreciated gift.

In the meantime, find out when and where to look for the space station to make an appearance. And remember: There are six people on board that dot of light screaming across the sky at eight kilometers per second. It’s an amazing thing to think about as you watch it.

Oct. 6 2014 11:23 AM

Slate Plus Doctor Who Podcast Episode 7: “Kill the Moon”

Because I love both Slate and Doctor Who, I’m pleased to let y’all know that the seventh installment of our Slate Plus Doctor Who podcast is now online, wherein I, along with writers and Whovians Gabe Roth and Mac Rogers, discuss the latest episode “Kill the Moon”.

You can go ahead and listen to it to get our spoilerrific opinions on the episode. However, I did have a pretty big issue with the show, but the podcast itself wasn’t long enough for me to dive into it; I wanted to cover more of the overarching themes than nitpick during the ‘cast.

But I have this here blog, so I’m going to nitpick. It’s about the science, so: SPOILERS HO.

Before I get started, let me preface this with a statement: I love Doctor Who. I always have. I take it for what it is: a story, a sometimes silly story, a sometimes profound story, a sometimes funny, goofy, serious, beautiful allegorical story. So please don’t attack me about how I hate the show, or am now a traitor, or whatever. I’m usually quite happy to overlook the spinning, folding, and mutilating of science in the service of Doctor Who plot, but I have a point to what follows; it’s not just nerdgassing (well, it is nerdgassing, but it's not just nerdgassing). Bear with me.

The biggest problem I had with this episode is that the science mistakes were so egregious and so obvious that they kept pulling me right out of the story. I know not everyone will know the science that well, and perhaps I’m being too hard.

But the thing is, a lot of the mistakes were fixable with a simple Google search.

For example, more than once the Doctor mentions that the Moon is 100 million years old. In reality, the Moon formed not long after the Earth did, certainly less than 100 million years after it. That makes the Moon something like 4.5 billion years old … a lot more than 100 million. I suspect the writers just got mixed up, but still, it was irritating.

If you want to retcon it, you could say that perhaps the creature’s gestation period is 100 million years, so this cycle repeats, and the Moon we have today is the 45th or so in a long line of them. But then the Doctor would have had to know that, and it didn’t seem that he did.

The Moon’s increase in gravity irked me, too. First of all, look at an egg. It’s a sealed, self-contained object, with everything it needs for the embryo inside to grow and hatch. Because of that, once it’s laid, it gains or loses very little mass (ignoring osmosis). If the Moon were to suddenly gain 1.3 billion tons (essentially overnight), where did it come from? The embryo inside an egg grows in mass by consuming what’s in the egg, so the egg’s mass overall stays the same. This magical mass increase bugged me a lot, especially since it was such a key point in the show.

Also, the amount (1.3 billion tons) of mass increase didn’t make sense. The Moon’s mass is about 7 x 1019 tons—50 billion times the mass of the creature! Adding a billion tons to the Moon would be hardly noticeable at all; like having a dust mote land on your head. The gravity of the Moon wouldn’t be affected, whether you were standing on it or on the Earth.

Note too that the creature was about the same size as the Moon itself. If it only had a mass of 1.3 billion tons, then its density would’ve been incredibly low. A cube of air 10 kilometers (6 miles) on a side would have a mass of about a billion tons, yet the creature was clearly thousand of kilometers long.

There was a lot more. Where did all that rest of the Moon go after the creature hatched? (The Doctor said it disintegrated, but the mass would still be there). How did the creature lay a new Moon-egg the same size and mass as before, if it itself was part of the Moon? Why did it have wings if it lives in space? How did no one notice the Moon was different after 2049? And don’t even get me started on the “prokaryotes.”

Any of these science missteps would’ve been irksome, but taken all together they really detracted from the program. And most would’ve been quite easy to fix with just a few minutes of time from someone who knew the numbers. I know, when you watch a time-travel show you’d best put strict scientific accuracy on the back shelf, but since the reboot, Doctor Who has taken some pains to fix a lot of the canon problems ignored in the show’s original run. I’d love to see more of that.

I’m sure that in due time I’ll watch the episode again. Perhaps with some distance I can ignore the scientific mistakes and enjoy the overall plotting better—after all, this was a key episode in the Who mythos; the Doctor has long said the 21st century is when “everything changes,” when mankind finally reaches for the stars (that was also the key phrase of Torchwood, the Doctor Who spinoff). As I watched, it really bugged me that such an important moment in the series was relegated to such a silly plot, especially after a couple of really outstanding episodes this season.

I really like the Missy/Nethersphere arc we’re seeing, as well as a lot of the odd and surprising turns to the Doctor himself (as well as Clara) this season. I really hope they can get back on their game and deliver more of what makes me love this program so.

Oct. 6 2014 7:00 AM

How to Lie With Data (or, “Melting Away Global Warming”)

Sick Planet Earth_stock

Sharon Jacob

First, the truth:

After a summer of seasonal melting, on Sept. 17, 2014, Arctic sea ice extent* likely hit its minimum for the year. The official word is that it was measured at 5.02 million square kilometers (1.94 million square miles). This is the sixth-lowest minimum since satellite records began in 1979.

It also fits right in with the overall declining trend of Arctic sea ice:

sea ice extent minima
Arctic sea ice minimum extents since 1979, when satellite measurements were started. This is the 2013 graph that I extended to add 2014's minimum. The blue line is a linear fit to the numbers.

Graph from NSIDC

As you can see, back in the late ’70s there used to be about 7.5 million km2 when ice hit its September minimum. That has dropped to about 5 million now, a decline of 30 percent. As you can also see from the graph, the past eight years have all seen lower ice extent than in the era previous.

This is due to global warming, overall heating of our planet due to human pollution. Dumping 40 billion extra tons of the greenhouse gas carbon dioxide into our atmosphere every year will do that to a planet.

Obviously, there’s no way to see this as good news.


Now, the legerdemain:

Oh, you foolish sheeple. Of course we can see this as good news.

For example, look at the minimum for 2012: It was 3.41 million km2. But the very next year the minimum was much higher, 5.1 million km2. That’s an increase of more than 40 percent! We’re on the road to recovery! Even this year’s minimum is far higher than it was in 2012, so obviously we’re doing great.

Back to the truth:

That’s a pile of horse manure. 2012 saw very unusual circumstances which led to far more melting then normal, so using it as a base point for comparison is unfair, to say the least. It would be just as unfair to look at the unusually large minimum in 1996 and say we had a huge drop after it. You have to look at overall trends. That’s why the blue line is there, and that’s how we know we’re in trouble. That line is heading down.

ice canyon
Overflow water from a melt lake carved this canyon in Antarctic ice; note the two people on the right for scale.

Photo by Ian Joughin, University of Washington via NASA

More shenanigans:

Ah, but that’s only the North Pole. At the South Pole, where it’s winter, Antarctica reached a record sea ice extent! It surpassed 20 million km2 for the first time on record! So much for global warming.

The inconvenient truth:

Part of that is actually true: Antarctic sea ice is at a record high. However, it doesn’t matter overall. That’s because Antarctica is a continent, a huge mass of land. Every year, sea ice around it comes (in winter) and goes (in summer), and over time tends to average out.

Since Antarctica is a continent, it makes a lot more sense to see what’s happening on land, not sea, since that ice should be more permanent (or at least not as ephemeral). But what we see there isn’t good at all.

Land ice in Antarctica is melting. Rapidly. Like, to the tune of 159 billion tons per year. In fact, West Antarctica has lost so much ice that it's measurably changed the Earth's gravity in that area!

Antarctic ice loss
Yikes. Note that the trend is down, and accelerating.

Diagram by NASA

Yet even more fertilizer:

But that’s West Antarctica. In the East, ice has actually increased!

Sadly, no:

That was kinda sorta true for a while but is misleading. First, warming waters around Antarctica means more moisture to create snow. Wind blows that around, and some of it fell in East Antarctica, creating mild ice increase.

Note the word “mild.” It wasn’t nearly enough to offset the tremendous loss happening in the west. And now we’re actually seeing increased ice loss in the east, too.

And don’t forget Greenland, back in the north. It’s losing ice rapidly as well.

One more bit of smoke and mirrors:

So what if we lose ice in the Arctic? It won’t increase sea levels, and it means we’ll have easier access to shipping routes!

Long, drawn-out sigh:

That’s more baloney, as Jon Stewart aptly showed recently. Losing land ice means sea levels will rise, and if we lose a lot of ice in Greenland and Antarctica—which we are very much on track for doing—sea levels could rise several meters. That would be catastrophic. Incidentally, salty sea water and clean melt water have different densities, so losing sea ice does in fact raise sea levels, though not as much as land ice loss.

By the way, some fossil fuel companies are excited about Arctic sea ice loss, because it gives them easier access to oil under the sea in the north. BANG! There goes my irony gland again.

So what does this all mean? Ice loss is an obvious indicator of a warming planet. Both poles are melting, so there you go. And it’s a bigger problem than just rising sea levels (which is a very, very big problem): Northern sea ice has been shown to affect overall weather patterns. Those bone-chilling cold snaps the U.S. East Coast has seen recently, heat waves in Alaska, and more are quite possibly connected to a weakening boreal jet stream due to warmer waters in the Arctic.

Got it? We’re destabilizing the climate system of our entire planet. We don’t know what exactly will happen as waters warm, as ice melts, as temperatures rise over years and decades. But we do know it means big changes, and we depend on the climate the way it is to support the seven billion souls on Earth, and those who will come after.

Monkeying around with our own planet is insane. Lying about it is even worse. We need to take global warming seriously, and we need to take action.

*“Extent” is essentially how much area of the Arctic was covered by ice; technically, though, area and extent are slightly different.

Oct. 5 2014 7:30 AM

Planet of Robots

My friends at Tree Lobsters put up a comic recently that's clever, and sweet ... and probably not what you think it is.

Tree lobsters

Drawing by Tree Lobsters

I put up the first two of four comic panels here; I don't want to spoil it. Go read the comic.

And let's not forget xkcd's take on a similar topic ...

Oct. 4 2014 7:30 AM

Ten Things to Know About Vaccines

October is Breast Cancer Awareness Month. This is a pretty good idea; I support raising awareness of a serious health issue.

… which is why I like to raise awareness of another serious health issue: anti-vaxxers. As it happens, for the past few years they have tried to hijack the idea of Breast Cancer Awareness Month for their own purposes. They’ve deemed it Vaccine Injury Awareness Month, and have been tweeting about it with hashtags such as #VaxTruth, #HearThisWell, and #CDCWhistleblower (that last in reference to an entirely overblown and factually challenged conspiracy theory about vaccines and autism research at the Centers for Disease Control and Prevention).

Update, Oct. 4, 2014 at 18:15 UTC: The paper that spawned the anti-vax conspiracy theory—about incidence of autism in African American boys after vaccination—has been retracted over concerns about conflicts of interest and use of incorrect statistical methods. This is pretty much exactly in line with what we had predicted and is a major blow to the anti-vaxxers ... not that I think they will stop using the paper as evidence anyway; they will just enlarge the conspiracy. Bet on it.

I learned about this reading Orac’s site. His frustration and anger over this issue is entirely understandable; we're dealing with a very important issue—threats to public health by terrible diseases—where people’s lives are directly at risk. And yet we have a group of people who are for the most part honestly concerned about the same issue, but don’t seem to understand the science behind it. On top of that, given that children are involved, many people are understandably upset and very defensive about the topic. This makes discussing it extremely difficult; from my own experience when I try to point out just why anti-vax rhetoric is wrong, no matter how delicately I put it, I get accused of all sorts of horrible things. The irony of the situation is palpable.

But the fallacious and dangerous reasoning of anti-vaxxers must be pointed out, and we must continue to point it out, because, like when fighting the diseases we keep seeing recur, you must periodically get a booster shot of reality to maintain immunity.

So I took to Twitter. Being no stranger to the irony, I decided to hijack the hashtags the anti-vaxxers have been using to hijack October, and put up a series of tweets telling the truth about vaccines. Here they are, in order, with a brief comment to give more info.

This is the key idea behind the anti-vaccination movement—vaccines are somehow causing autism incidence to rise—and it’s entirely without merit. Everything else comes from that: the idea that vaccines have toxins, the scheduling is too many too soon, and so on. None of those ideas pans out, but that doesn’t stop a lot of anti-vaxxers from rehashing them.

This is one I’ve seen a lot, and I’m glad Dr. David Gorski put up a simple debunking of it. The reason we don’t have hundreds of thousands of measles cases every year in the U.S. is due to vaccines.

Some anti-vaxxers try to downplay the role of vaccines, but the reason we don’t see smallpox anywhere at all, ever, is due to a global smallpox vaccine campaign. And we’re seeing increasing uptake of vaccinations reducing illnesses worldwide, too.

Follow the links; Andrew Wakefield’s work has been thoroughly discredited, he’s been accused of fraud, and even his co-authors on the original paper have abandoned him. And did you know that he stood to make hundreds of millions of dollars by inciting fear of the MMR vaccine? This is something science-based vaccine researchers are accused of by anti-vaxxers quite often.

This is not terribly surprising. In places where we've seen outbreaks of vaccine-preventable diseases, vaccine uptake rates are low. And in many of those places, there are direct links to pockets of people resisting getting vaccinations. Sometimes you can pretty easily pin causation to correlation.

In general, the three most vulnerable groups to vaccine-preventable illnesses are infants too young to be vaccinated yet, the elderly, and people who are immune-compromised (those who are allergic to the vaccines, people undergoing chemotherapy, and so on). When you don’t vaccinate, you can be a carrier for diseases against which other people cannot protect themselves.

Sure, it’s your body, and your choice. But make sure you’re making that choice with all the information. You can spread diseases long before you know you even have them, and someone else may pay the terrible price for your choice.

And in a more general sense, we need as many people vaccinated as possible, to maintain herd immunity and protect those who cannot protect themselves.

Self-explanatory. Yet we need to explain it again and again.

This article, written by my friend Rachael Dunlop, is an excellent resource to debunk long-overused tropes of the anti-vax movement. Keep that link handy.

I get accused of talking the talk sometimes, and I think it helps to show I put my money where my mouth is. I’m fully vaccinated, as are my wife and daughter. We do this for ourselves, and to protect those around us, too.

I could make that list a lot longer, but that link and those people on Twitter are an excellent start for finding the truth about vaccines. To wit: Vaccines are effective, their risk is incredibly low, and they are one of the greatest health benefits humans have ever devised.

Go talk to your board-certified doctor, and find out if you need to get any vaccinations or boosters. Thanks.


Oct. 4 2014 5:30 AM

“Stormscapes”: Mesocyclone Time-Lapse

What, a gorgeously shot series of mesocyclones and other storms recorded forming in a time-lapse video? Yeah, you know I want to show you that.

Those are amazing. They were shot by Nicolaus Wegner in 2013 in Wyoming. Mesocyclones are mesmerizing, and I’ve written about them many times before (and explained how they form). I’m still interested in the deep aquamarine color that sometimes appears, too. It’s not well understood.

Hypotheses abound, including light bouncing off hail, and somehow the red setting Sun contributing to the green color of the sky (presumably by contrast; they way our eyes perceive color depends quite strongly on what other colors are nearby).

I’m not exactly sure how you could figure out what causes it; tests in the field would be difficult given the circumstances. Perhaps a spectrum could be taken, and the various contributing factors teased out. Is the green light strongly polarized or not? That might also be a clue to how the color is generated.

At some point I’d love to dig into this further. It’s an interesting and puzzling problem, and those are the most fun kind.

Tip o’ the umbrella to the Rain Forest Site.

Oct. 3 2014 7:30 AM

Ma Halo

Imagine you’re on an island paradise, staying up very late and enjoying your view of the dark sky on a warm predawn morning. Suddenly, your reverie is interrupted by a bizarre and frankly eerie sight: Rising over the horizon is a huge circle of light, a glowing smoke ring that gets bigger as it moves silently across the starry vault. After several minutes, growing the whole time, it finally dips below the far horizon, leaving you stunned and wondering if you’ve lost your mind.

Last week, I got two emails from two different people describing just this sort of event. I knew what they were telling me was real … but not because the two reports were independent of one another and not because one of them sent me the amazing picture displayed above.

I knew it was real because I knew right away what event they were describing. I’ve heard these stories before. Once was in 2009 when such an event freaked out people all over Norway, and two have been seen in recent years over Hawaii—one in 2011 and another in 2013.

Hawaii, you say? The folks who sent me the emails were both on the Haleakala volcano on the Hawaiian island of Maui. And both saw the halo around 04:30 local time on Tuesday morning, Sept. 23.

Aha! They had just seen a suborbital missile on its way across the planet after a test launch.

That’s what was seen from the same area in 2011 and 2013. A Minuteman III ICBM was launched from Vandenberg Air Force Base in California, and while it’s in space the third stage performs a fuel dump. When the material is released, it expands as a spherical shell in the near-vacuum of space, and looks very much like an expanding, glowing soap bubble. It also moves rapidly across the sky, since it maintains the momentum of the rocket itself moving at several kilometers per second.

I looked again at the picture I was sent. If the launch was from California, people seeing it in Hawaii would see the halo approaching from the northeast. And sure enough: If you look at the picture, you can see the four stars comprising the bowl of the Big Dipper on the left side of the halo. This picture was taken facing northeast.

minuteman launch
The Minuteman III launch in question; the missile is halfway up the plume. Note the flaming debris at the top, blown out of the silo faster by pressure from the engine exhaust.

Photo by U.S. Air Force / Joe Davila

OK, so it was a Minuteman launch. However, I poked around and couldn’t find any launch info. As I do in situations like this, I went to my friend Jonathan McDowell, who is a space aficionado and keeps tracks of all launches. He showed me that, indeed, there was a test launch of a Minuteman III intercontinental ballistic missile from Vandenberg Air Force Base on Tuesday morning at 7:45 a.m. Pacific time—4:45 Hawaii time. Aha again!

Jonathan pointed me to an article about the launch on the Vandenberg website, too. I contacted the public affairs office there, and they told me that in fact the launch was to the southwest, so the missile would send its payload into the Pacific Ocean near Kwajalein Atoll, where there’s a military installation. Mind you, a Minuteman is designed to drop nuclear weapons on a target, so tracking the launch down to the impact is important. In this case, you may be somewhat relieved to note, the payload was a dummy for the missile test.

Case closed.

One of these days, I hope to see something like this. I’ve watched countless satellites pass overhead, and even witnessed two or three rocket launches. But to see that weird halo of light gliding silently across the sky, growing ever larger as it moves … that would be pretty amazing. Someday.

Oct. 2 2014 7:30 AM

What Put the Man in the Moon in the Moon?

There’s an old phrase: “To someone with a hammer, everything is a nail.”

Asteroids are the ultimate hammers. After all, an asteroid impact can certainly pound a nail into the toughest medium! Because of that they’re blamed for all sorts of features in the solar system. But a new paper claims that one of the largest features on the Moon—Oceanus Procellarum, the “Ocean of Storms”—was actually not caused by a giant impact, as has long been thought.

Instead, it may have been formed due to an enormous series of volcanic rifts.

The feature in question.

Photo by NASA/GSFC/Arizona State University

Procellarum is a huge flattened region of the Moon, dark lowlands dominating the Moon’s northwest face. It’s part of the fabled “Man in the Moon” formation. The region is a good 3,200 kilometers (1,800 miles) wide, which is huge. The overall shape was always assumed to be circular, but to be fair it’s difficult to say.

It formed long ago, about 3.5 billion years ago, and subsequent impacts (some of which have been huge) have distorted the outer boundaries. Because of its huge size and assumed roundness, its origin has generally been attributed to something very large hitting the Moon, punching through the crust. Magma welled up, creating vast plains, which eventually became the Procellarum we see today.

But the new study challenges that. Researchers used gravity data to look at features in and below the surface, and get a different story. The data came from GRAIL, twin spacecraft that orbited the Moon in formation. The Moon isn’t a homogeneous sphere; it’s lumpy, with places under the surface with higher and lower densities. This means those regions will have higher and lower gravitational pull. As the first spacecraft flew over such a region, it would speed up or slow down relative to the second one. This could then be used to determine the density of the underlying terrain.

What they found was not what was expected: A series of long, narrow features that look like rift structures, places where the Moon’s crust is thinner, and which are generally associated with upwelling magma. The structures form a rough square or pentagon that neatly outlines the lowlands.

Msp showing the rifts (dark lines) which kickstarted the idea that volcanism created Oceanus Procellarum. This topographical map shows the depression; the darkest blue is 5 km below average, dark red 5 km above.

Diagram by Andrews-Hanna et al., from the journal paper

This changes the way they interpret the formation of Procellarum. Instead of a single huge impact, these rifts formed and magma started to seep (or more likely flood) through. It flowed downhill, toward the interior of the polygon. Eventually, the pressure from the weight of the overlying lava compressed the crust, closing the rifts, shutting off the flood. The lava plains cooled, and later impacts formed the other basins seen overlapping it.

The scale of this is mind-numbing: Imagine an eruption of lava so big and so long-lasting it flooded 2.5 million square kilometers of lunar surface! That's an area a quarter the size of the entire United States.


Despite its apocalyptic nature, there’s a lot to like about this new idea. The observations make a neat fit, for one thing. For another, I’ve always had a problem with the impact idea; the size of the impact was so big it should’ve had lots of secondary effects. For example, the shock wave in the crust would have traveled around the Moon, converging on the spot on the opposite side (called the antipode). This dumps lot of energy there, and you should see chaotic, jumbled terrain in that area (this is seen with Mare Imbrium, or “Sea of Rains”, for example). Yet there’s no indication of such a feature.*

This paper just came out, and knowing scientists as I do, I expect there to be a lot of discussion and arguing over the data and results. That’s a rock-solid (har har) guarantee when a new idea challenges a long-established one, especially when it’s something as basic as the formation of a huge feature.

But that’s part of the fun! Now we have to figure out which idea is not just good, but better, and then think of ways of testing them both to compare them. One idea may win, or maybe both will (sometimes multiple causes form a single feature), or maybe a third idea will well out of the cracks. Remember, this new idea was only made possible due to new ways of studying the Moon (GRAIL flew in 2012). The more we study our nearest cosmic neighbor, the more likely it is we’ll find surprises lurking just below the surface.

* Though I did find a paper saying the Procellarum may have been formed due to antipodal effects of the South Pole Aitken Basin, which is interesting.

Yup. Couldn’t resist.

See .

Oct. 1 2014 12:01 PM

Rocky Snow

Boulder snowfall.
Mount Meeker and Longs Peak got a decent snowfall on Sept. 30, 2014. Click to tectonicate.

Photo by Phil Plait

Mount Meeker, left in the image above, just got a dusting yesterday, but Longs Peak, to the right and behind Meeker, got a bit more. Some of the mountains to the south and west got a goodly amount, too.

We've had very bad droughts and floods here in the Boulder, Colorado, area over the past few years. Here's hoping for a nice, cold, regular snowy winter.