The entire universe in blog form

Sept. 2 2014 11:30 AM

New Observations Confirm Greenland, Antarctica Losing Land Ice Rapidly

A new study just published shows that—using more accurate measurements than ever before—Greenland and Antarctica are together losing ice at incredible rates: Together, over 500 (±107) cubic kilometers of ice are melting from them every year.

That means 450 billion tons of ice are lost every year, melted away into the oceans. That’s staggering.

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Tim Radford at the Guardian has the story. In a nutshell, the European CryoSat-2 satellite measures the height of the ice over the two land masses. As they lose ice, the height drops, and that change is seen by the satellite.

This loss is of course due to global warming; we’ve known for some time that land masses at both poles are melting away their ice, but these new measurements confirm the bad news, and give more accurate numbers. They also found that West Antarctica—the focus of much concern lately—is losing ice three times faster now than it was in the time period from 2003–2009. That’s astonishing. Note that they did find a mild increase in ice in eastern Antarctica, which was known before as well, but it’s not nearly enough to compensate for the huge losses elsewhere (in other words, beware of The Usual Suspects trying to use this to say land ice is increasing).

I can’t help but mention that I saw this news literally the day after an atrocious Mail Online article also reported on satellite imagery of the North Pole but then grossly misinterpreted it to make the claim that Arctic sea ice is recovering from the record loss in 2012. As I pointed out yesterday, that claim is just so much fertilizer. The contrast between the Mail reporting and that of the Guardian can’t be more different. The latter is trustworthy, the former … less so.

Be careful where you get your news about anything, of course, and especially when it’s about scientific issues that have become political ones. It seems that a lot of venues out there are going to great lengths to keep people in the dark about global warming. I will do what I can to shine a light on them.

Tip o’ the snow plow to Dana Nuccitelli.

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Sept. 2 2014 7:30 AM

Mystery No More: The Sliding Stones of Death Valley

Oh how I love nature and science! The former sets up mysteries that baffle us, and then the latter equips us with tools with which to solve them.

When I was a kid, one of the coolest mysteries going was the moving stones of Racetrack Playa. This is a dry lake bed in Death Valley, California, where large rocks are embedded in the dried mud. However, many of the rocks have clearly been moving; there are long tracks behind them in the caked, baked mud pushed up like rails along the tracks’ sides.

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What could be moving these stones? No one knew. They would sit for years, then suddenly be found to have moved many meters. Could wind push them? Maybe ice formed after rain, forming rafts that floated the rocks up. Speculation abounded, and I remember watching TV shows about the rocks, and reading about them in sketchy “Mysteries of the Paranormal” type books when I was a wee lad.

Now, however, this enduring mystery has been solved. And I mean, solved. Like, we know what’s causing this. A team of scientists and engineers were able to capture the motion on camera, finally revealing the mechanism behind this bizarre behavior.

It was wind. And rain, and ice. But not quite the way it was thought before. Here’s a video describing it, from one of the scientists, Scripps paleo-oceanographer Richard Norris:

In a nutshell, the playa is very dry, getting only a few centimeters of rain per year. In the winter, when it does rain, the slightly tilted playa gets accumulations of water a few centimeters thick at one end. It gets cold enough for the water to freeze on top. When the Sun comes out, the ice begins to melt, forming large chunks called rafts. The wind blows these rafts (which are typically a few millimeters thick), which then hit the rocks and push on them. The ground is softened by the water, so the rocks can move more easily ... and then they do.

The team set up a weather station, time-lapse cameras, and 15 rocks with GPS units embedded in them. With this equipment, they were able to capture and record the motion. The rocks move at slow speeds, perhaps a few meters per minute, but that was enough to get caught on camera. Here’s one (indicated by the red arrow; in the background are two stationary rocks indicated by blue arrows) in action:

rock moving
The movement of one of the Racetrack Playa rocks over the course of about 14 seconds. The lighter rippled material is open water; the darker smooth patches are ice.

This also explains why sometimes several rocks show not only parallel trails, but also apparent simultaneous changes in direction; the sheets of ice were blown by the wind, and when the wind blew from a different direction, the ice sheets responded.

Wind alone couldn’t do it, and the ice wasn’t acting as a buoyancy agent, either. It was basically sheer muscle power, surprisingly, given how fragile you might think that ice was. I think that’s one of the reasons no one seriously considered this as an explanation before.

multiple rocks
Tracks left by multiple rock are parallel, apparently making the same angled turns at the same time.

I love this. It makes me ridiculously happy to see this. There’s so much wonderfulness to it! A mystery that’s lasted for decades, no explanations that ever seemed to completely work, then a devoted and dedicated effort was mounted … as had previous ones, but this one got a big stroke of luck, catching this movement on several occasions when the events might not happen for a decade at a time.

At this point I have to disagree with my friend Zach Weiner, who put together a compilation of his Saturday Morning Breakfast Cereal comics into a book called Science: Ruining Everything Since 1543.

Science! It doesn’t ruin anything.* It reveals the amazing, subtle, wondrous, and simply cool mechanisms that make the natural world what it is: endlessly fun.

*At least, nothing that doesn’t deserve to be ruined. Also: I’m in that book, and you should buy multiple copies, because in the end I still think Zach’s the bee’s knees.

Sept. 1 2014 7:30 AM

No, You Can’t Claim Arctic Ice Is “Recovering”

Sigh. Here we go again.

The Daily Mail and Mail Online are to scientific accuracy what a sledgehammer is to an egg. Especially when it comes to global warming.

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David Rose is oftentimes the wielder of that sledgehammer. He’s written error-laden climate articles in the past, like saying that global warming has stopped (no, it hasn’t), that the world is cooling (no, it really really isn’t), and that the Intergovernmental Panel on Climate Change had to hold a crisis meeting because Rose’s articles have caused such a fuss (that meeting never happened, which Rose had been told several times, but he still made the claim). Other examples abound.

This time, in Sunday’s Mail Online he writes that Arctic sea ice, which hit a major record low in 2012, “has expanded for the second year in succession.”

This claim is a humdinger, and typical denial double-speak. It’s technically true, but also really wrong. It’s like examining someone who has a 106° fever and saying it’s really made their skin glow. But what do you expect from an article that has this breathless headline:

Myth of arctic meltdown: Stunning satellite images show summer ice cap is thicker and covers 1.7million square kilometres MORE than 2 years ago...despite Al Gore's prediction it would be ICE-FREE by now

“Myth of arctic meltdown” is enough to tell you just how slanted and wrong the conclusions of this article will be … and the inclusion of Al Gore’s name brings it home. Mentioning Gore is at best a distraction, red meat to the deniers. Gore isn’t a climate scientist, and as we well know actual climate scientists overwhelmingly agree that the world is warming. One of the outcomes of this is the decline of Arctic sea ice.

Briefly: Arctic sea ice reaches a minimum in late September every year. The overall trend for the amount of ice at that time is decreasing; in other words, there is less ice all the time. Some years there is more than others, some less. But the trend is down, down, down.

In 2012, a mix of unusual causes created conditions where the minimum reached a record low, far below normal. The next year, in 2013, the ice didn’t reach quite so low a minimum extent, and this year looks very much the same as 2013. But saying the ice is “recovering” is, to put it delicately, what comes out the south end of a north-facing bull. You can’t compare two years with a record low the year before that was due to unusual circumstances; you have to look at the average over time.

Of course, if you do, your claims that global warming isn’t real melt away.

Yearly ice extent.
Arctic ice extent for 2012–2014, with the average for 1981–2010 in black.

Graph by NSIDC

The black line is the average for 1981–2010. The gray region shows the ±2 standard deviation extent for that average; statistically speaking it’s an expected range of extent (it’s actually more subtle than that, but that’s enough to understand what’s going on here). The dashed line shows the 2012 ice extent, and is clearly very low, well outside the expected range. The brown line is 2013, and the light green line is this year, 2014, up to late August. Notice 2014 follows the year before pretty closely.

Note also they are well below average, near the bottom of the expected range. If you look at any recent year’s ice it’s below average; you have to go back to 2001 to find an ice extent near the average.

So the claim that the ice is “recovering” is made based on the wrong comparison. Compare the past two years to the overall trend and they fit in pretty well with overall decline.

Also, that “recovery” claim cannot be made with only two data points. Two years is not a trend. There have been many times ice has gone up over a year or two in the Arctic, only to drop once again over the long run.

ice extent anomaly
Sea ice anomaly, showing annual ice extent versus an average value.

Graph by NSIDC

That’s also from NSIDC, and it shows the ice extent for August of every year from 1979 to 2013. Yes, in 2013 it goes up, but note: 1) There are several times it jumps up for a year or so, but 2) the overall trend is down. Looking at two data points in a row and ignoring everything else is incredibly misleading at best. David Appell at Quark Soup shows this very clearly as well.

There’s plenty more to debunk about Rose’s article, but this shows that his central premise is dead wrong. You absolutely cannot say Arctic ice is recovering, and in fact everything we know—like rising temperatures, and how the Arctic is more sensitive to warming than the rest of the world on average, and the obvious long-term trend—is that we are still losing Arctic sea ice at an alarming rate.

And don’t believe the tired malarkey you might hear about Antarctic sea ice increasing; that has nothing to do with any of this, and is hugely offset by the tremendous land ice loss every year anyway.

What makes this even more aggravating is that there’s nothing new here. This claim of Arctic ice recovering was made last year, and it was just as wrong then as it is now. It’s shameful. Global warming is real, it’s a huge problem, and it’s our own damn fault. There’s still time to fix this, though that breathing room is getting slimmer all the time … and it’s not helping when media give air to deniers.

Correction, Sept. 1, 2014: In the original version explaining the first graph, I wrote "temperature" when I meant "extent." My apologies for any confusion.

Aug. 31 2014 8:00 AM

Time-Lapse: The ESO Observatories

The northern part of Chile is a forbidding and remote desert. Called the Atacama, it is one of the driest places on Earth, and also reaches high elevations; in some places the desert floor is 4,000 meters above sea level … and that’s not counting the numerous mountains and volcanoes that stretch even higher.

All of this is why the Atacama is home to some of the finest astronomical telescopes observatories on the planet. The clear air lets through a lot of light, visible light as well as other flavors invisible to the eye, and the landscape is dotted with bizarrely shaped observatory buildings and arrays of dishes pointing skyward.

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The European Southern Observatory commissioned some of the best astrophotographers in the world to travel to Atacama and capture the ethereal and literally unearthly beauty of the desert … and one of the results is this wonderful time-lapse video called “The ESO Observatories: Atacama Transitions and Landscapes under the Southern Sky” taken by friend-of-the-BA-blog Christoph Malin. Watch.

There’s a lot to see, but I think my favorite is at 6:45, when a bright fireball lights up the sky (that’s the still at the top of this article); you can actually see different colors in the meteor streak, most likely due to different elements burning off it as it plunged into our atmosphere from space.

Right after that, you can watch as the multiple dishes of the ALMA array dance in synchronized perfection, moving in unison to capture faint millimeter waves trickling down from distant cosmic sources.

Also, starting at about 9:50, the buildings housing the magnificent four-part Very Large Telescope come into view, each an 8.2 meter behemoth. At first it’s quite normal appearing, but then the powerful laser erupts from one building, a science-fictional beam that is used to aid the telescope in removing distortion from the ocean of air above our heads. As you can imagine, they have to be careful and coordinate with the local air traffic authorities; such a device wouldn’t be a good mix with an airplane flying into the beam.

Finally, I want to point out a phenomenon that is both subtle and astonishing: At 10:20, with the Milky Way’s companion galaxies the Magellanic Clouds hanging on the left and a mountaintop silhouetted in the center, you can see faint, colorful bands of light moving in from the right side of the frame. This is almost certainly airglow, caused by atoms and molecules nearly 100 kilometers above the ground giving up the energy they absorbed from the Sun during the day. This commonly is red and green, as seen in the video.

The ripples in them are amazing. There is wind in the air, even so high off the ground. If it blows steadily across the air below it, ripples can form in the boundary layer (they can also be caused by atmospheric disturbances like thunderstorms, too). These are called gravity waves (the Earth’s gravity fights with buoyancy, and the result is the oscillation of the air, moving it up and down like a cork in water). It’s similar to the phenomenon of ship wave clouds, which happen much closer to the ground.

As usual, there’s far more going on over our heads than we appreciate. Sometimes, it’s when we train our cameras to the sky—and allow them to play with time and space and brightness and color—that we can truly see the exquisite machinery of the heavens.

laser
A laser beams out of one of the VLT observatory buildings.

Photo by ESO

Aug. 30 2014 11:57 AM

Two Days Previously

Heh. What was the view like two days before the video I posted this morning?

This:

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So. COOL.

That's the Orbital Sciences Corporation's Cygnus resupply ship (the Janice Voss) at the end of the space station's Canadarm 2, then leaving in a hurry in this time-lapse video taken on Aug. 15, 2014. The resupply ship brought well over a ton of supplies to the astronauts, and had been reloaded with trash. It was unberthed by the remotely controlled arm (operated by Alex Gerst on the ISS), then commanded to head off. Two days later, it burned up re-entering Earth's atmosphere.

Watching this video I noticed a peculiar thing: It appears to go up, away from the Earth, instead of down toward it. I suspect this is at least partly due to the pictures being taken with a wide-angle lens, which distorts the image; for example, the Earth isn't nearly that curved when seen from ISS. However, the ship didn't burn up until two days later, so it's likely it wasn't sent immediately into a de-orbiting path, so it may have just moved ahead of ISS for a while before dropping down. Things like this can be difficult to track down, so I'll see what I can do to get more info. 

In the meantime, the video is mesmerizing, isn't it?

Aug. 30 2014 7:30 AM

Swan Dive

Cygnus reentry
The Cygnus resupply vessel burning up upon re-entry to Earth's atmosphere on Aug. 17, 2014. Click to enmeteorenate.

Photo by NASA

A couple of weeks ago I posted a dramatic picture (above) of the Orbital Sciences Cygnus resupply ship, the Janice Voss, burning up on re-entry after a successful mission to the International Space Station.

Yesterday, astronaut Reid Wiseman posted an incredible Vine video of the event. Watch this!

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Wow. I mean seriously, wow. That’s video of a spaceship burning up as seen from above by astronauts on a space station orbiting the Earth.

People keep complaining that we don’t have flying cars. Those people are silly. The future: We are in you.

Aug. 29 2014 7:30 AM

The Closest Known Exoplanet? Maybe …

In 1992, the first planets outside the solar system were discovered, orbiting the dead cinder of a supernova. Three years later, 51 Peg was found, the first exoplanet orbiting a Sun-like star. Now, after a decade of searching, we have a roster of nearly 2,000 such planets, alien worlds circling alien stars.

They come in many varieties, with some being huge, Jupiter-like behemoths, and others far closer in size to our own hospitable planet. Weve found them around distant stars hundreds of light years away, and some much closer.

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And that brings us to a newly found planet just announced: Gliese 15Ab. It has a mass of about five times Earths, which is interesting in and of itself; that makes it a super-Earth, if you will, a planet bigger than us but perhaps not quite massive enough to gravitationally attract a thick atmosphere. We dont know much about what its like, but its probably not a gas giant.

But thats not the interesting bit. The interesting bit is that its host star, Gl 15A, is a mere 11.7 light years from Earth. Its one of the 20 closest stellar systems known, making GL 15Ab quite possibly the closest known exoplanet!

Gliese 15 is a binary star, two cool, dim red dwarfs orbiting each other. Red dwarfs are the most common type of star in the galaxy, but theyre so intrinsically faint that not a single one is visible to the naked eye; you need a telescope to see them. The closest star to the Sun we know of, Proxima Centauri, is only 4.2 light years away and even then too faint to see without using at least good binoculars.

Gliese 15 A and B (as the two stars are called, or just Gl 15A and B for short) orbit each other at a distance of about 22 billion kilometers, which is five times the distance Neptune orbits the Sun, so theyre pretty far apart. The planet discovered has a very tight orbit around the brighter of the two stars, Gl 15A, circling it a mere 11 million kilometers out. Thats close. Even though the star itself is a dim bulb, the planet is so near to it that its heated to at least the boiling point of water, and possibly hotter.

Gl 15Ab was found using whats called the Doppler shift (or reflex velocity) method. Because the planet has significant mass, as it orbits its parent star in a big circle, the star itself makes a smaller circle every orbit, too. They actually each orbit their mutual center of mass, called the barycenter, like two kids facing each other, holding hands, and swinging each other around. If this sounds familiar, I just wrote about this recently because Pluto and its largest moon, Charon, do the same thing, and this was seen by the approaching New Horizons space probe.

We dont actually see the star and planet move, but as the star approaches us in its orbit its light gets slightly blue-shifted, and as it moves away the light red shifts. The change is incredibly small, but the team of astronomers used the huge Keck 10-meter telescope with an extremely high-resolution detector. Their observing campaign has gone on for 11 years, enough to detect the planet pretty well. To be clear, they didnt see the planet directly; they only saw its effect on the star. But this method has proven out many times, and is quite reliable.

The amount the planet can tug on its star depends on its mass, which is how they found the planet to have 5.35 ±0.75 times the mass of Earth, and by measuring the period of the oscillation determined its year to be just 11.44 Earth days long. Thats how they know it orbits the star so closely; thats a short year!

Were still new at all this, the finding of alien worlds. But were pretty good at it. We know of enough to start looking at them statistically, as a group, able to make some solid extrapolations. Given what weve seen so far, we think there are billions of planets in our galaxy alone. Billions! Its like a Star Trek fever dream come true.

Given those odds, its not terribly surprising to find a planet so close to home. Ill note that this planet isnt technically confirmed; that is, also found by another team of astronomers or also seen using other methods (like undergoing transits). Still, this observation looks pretty solid, and if so this makes it one of if not the closest known exoplanets. A handful of other planet candidates have been found that are closer, but none is confirmed. There are fewer than 30 known stars and brown dwarfs (substellar objects that are similar to stars but smaller) closer than Gliese 15; many are in multiple systems, binaries or trinaries, so its entirely possible well find and confirm a closer planet still.

But even with all that, this goes to show that the sky is likely filled with planets, and many of them are pretty close to us in a cosmic sense. It also shows just how hard it is to find them! Eleven years of searching with one of the largest telescopes on Earth, and it was still a difficult task. But were getting better at this. If there are more, closer planets out there, well find em.

Tip o the warp nacelle to Dan Vergano.

Aug. 28 2014 7:30 AM

Double Rainbow ... With Lightning!

One of the things I love about living in Boulder, Colorado, is that in the summer we tend to get afternoon storms. It’s sunny a lot here, which heats the land and evaporates water, forming clouds, and they can get a tremendous amount of energy in them. We get good downpours, and then when the storm is done, it’s done.

Because the wind blows predominantly west to east, and the storms are in the afternoon when the Sun is setting, when the clouds clear from the west the Sun shines through. If it’s still raining here, we can get extremely bright rainbows.

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That weather pattern was common for the first couple of years I lived here, but in recent years it’s slacked off. But it’s coming back: Yesterday was a textbook case of this, and the rainbow was amazing.

Yeah, double rainbow all the way. The glow around my head’s shadow I was describing is called heiligenschein. The other optical effects—the secondary arc, the supernumerary arcs, the bright region in the center and the dark band—I’ve described recently in a post about red rainbows.

The lightning was amazing. It was so fast I didn't get a good look at it—I was paying attention to the phone screen to make sure the rainbow was visible in it—and for a moment I thought it might have been sunlight reflecting off raindrops. Then a few seconds later the thunder slammed down. It was far louder than it sounds on the video. It took about eight seconds to reach me, so the lightning was less than three kilometers away. Quite the show.

rainbow
Double the magnificent optical displays.

Photo by Phil Plait

I will never get tired of seeing things like this. Rainbows are almost cliché, but they’re one of the most magnificent optical displays nature can provide. The science behind them is really intriguing, and to me, it amplifies their beauty manyfold.

Aug. 27 2014 1:10 PM

The Slate Plus Doctor Who Inaugural Podcast

Note: Extremely mild spoilers below. I figure I might as well warn you.

As an unapologetic and enthusiastic Doctor Who fanboy, I’m really happy that the new series has started up. We’re in Season 8 now, with Peter Capaldi now (metaphorically) filling the Doctor’s fez. The first episode just aired, and I thought it was pretty good. I even tweeted it:

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So it’s official.

The Hive Overmind at Slate asked if I’d like to do a podcast with various Slate-sters discussing the new episodes of Doctor Who as they air. I said yes—duh—and the first one is now online. I spent about an hour talking Whovianicity with Slate’s Outward editor and culture critic June Thomas. We talk Clara, Capaldi, robots, Silurians, and why I thought the regeneration was handled pretty well. We also had some fun with a certain locking of lips shown in the episode as well.

Fair warning: The podcast is part of Slate Plus, which is a premium subscription service. It’s five bucks a month, and provides all kinds of fun added content; I’ve written about it before. There’s a lot of great stuff there on top of the usual great stuff at Slate, so I heartily recommend signing up.

If you need another reason, we’ll have a new Doctor Who podcast every week during the season. So join in and be a part of the fun!

Aug. 27 2014 10:30 AM

An Island Grows in the Ocean

Back in March I posted a Landsat 8 image of a volcano called Nishinoshima, located in the Pacific Ocean about 1,000 kilometers south of Tokyo. Up until late 2013 it was just a dinky island barely poking above the water’s surface. But then a second vent started erupting nearby, rapidly grew in size, and actually engulfed the original volcano.

It’s still growing. This new view from Landsat on Aug. 21, 2014, shows it puffing away:

Nishinoshima
(Don't make a Godzilla joke, Phil, don't do it.) Nishinoshima island. Click to godzillanate. (D'oh!)

Photo by Jesse Allen, using Landsat data from the U.S. Geological Survey

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It’s interesting comparing it to how it looked a few months ago; it’s clearly changed its shape. It’s not growing as rapidly as it once was, apparently, but it’s still getting bigger.

That whole area is loaded with volcanic islands forming seriously long chains across the ocean:

The pin marks the location of Nishinoshima. Of course, that map is scaled way out, covering thousands of kilometers. The original Landsat image gives you a better sense of how lonely the island is out there:

Nishinoshima
A wider view. It's a big ocean, and this image is only about 50 km across.

Photo by Jesse Allen, using Landsat data from the U.S. Geological Survey

Pretty. And fascinating. It shows that our planet is active, constantly changing, constantly renewing itself. If it didn’t, we’d probably look a lot more like Mars. That’s a pretty amazing planet too, but given its lack of a thick atmosphere, no water, and chilly room temperature, I’ll take Earth every time. I like my environment habitable, even if it means some locally isolated places really aren’t.

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