Scientific American editor Davide Castelvecchi joins us from San Francisco to talk about some of the highlights of the meeting of the American Geophysical Union, including volcanoes on Titan, x-rays from lightning, the biota of the Sulawesi Sea, and the connection between light pollution and air pollution. Plus, we'll test your knowledge of some recent science in the news. Web sites related to this episode include sciencewriter.org; snipurl.com/planethunters; snipurl.com/titanspew; snipurl.com/lightningx; snipurl.com/sciamadvances
Steve: Welcome to Science Talk, the more or less weekly podcast of Scientific American, posted on December 16th, 2010. I'm Steve Mirsky. We've been gone for a little bit but we're going to be spooling out a bunch of shows for you in short order between now and the end of the year. In this episode, one of our physics and astronomy writers, Davide Castelvecchi, reports from the meeting of the American Geophysical Union in San Francisco. We spoke on Wednesday, December 15th.
Steve: Davide, I know you've been to some interesting sessions there this. There's new information about Titan. What's going on out there—for Kurt Vonnegut fans too?
Castelvecchi: In fact, the NASA led Cassini mission keeps finding new amazing features on Saturn and on its satellite. The most interesting one this time was on the largest of its satellites, which is Titan; and it was the first positive identification, or at least scientists feel it the most compelling evidence so far, for cryovolcanoes—that means icy volcanoes—in the solar system.
Steve: Icy volcanoes? What are they spewing?
Castelvecchi: They are spewing liquid water out of a world of ice. So imagine you have an icy surface, like you have in Antarctica or Greenland, and there's a volcano that instead of spewing lava, spews liquid water.
Steve: What's going on beneath the surface, you know, on the Earth we are used to geological activity that's bringing molten material up to the surface. What's going on, on Titan that would make liquid water come out of a volcano on a frozen ice surface?
Castelvecchi: That's a big mystery and one possible answer is that there is tectonic activity because of the passage of other moons nearby that kind of perturbs the gravitational field around Titan and the resultant [forces] could add stress on the icy surface; and so if there's any pockets of water in there, the water could be squeezed out, and then you could have a plume coming out of the surface, or perhaps just flowing like a source of a river on the Earth's surface.
Steve: And presumably once that water reaches the surface it will refreeze, and is there some kind of, on Earth you've, you know, subduction of plates; is there some kind of a mechanism whereby the solid ice on the surface then gets trapped beneath the surface and could wind up, you know, someday again getting spewed out of one of these frozen volcanoes as liquid water?
Castelvecchi: There isn't a lot of tectonic activity, apparently, on Titan; at least not in a long [time], there hasn't been in a long time. But what is interesting is that the water flows on the surface the way that lava would flow out of a volcano on Earth, and it takes a little while for it to solidify. And so what happens is year after year, century after century, this frozen, watery lava keeps adding material and eventually it forms this conical, you know, this cone-shaped structure which is similar to volcanoes you see on, the actual volcanoes, you see on Earth.
Steve: So what does this all mean for our understanding of Titan and the Saturn system?
Castelvecchi: Well, the most interesting thing apparently is that there's been a longstanding mystery as to why there's so much methane in the atmosphere. Titan has a lot of methane in the atmosphere, like natural gas, and it forms clouds and it rains and it forms lakes. But the problem is, sunlight breaks down methane in the upper atmosphere of Titan, and so after awhile, if there were a fixed amount of methane, after a while over geologic time, it should all break down. So there must be some process that replenishes the methane; and people have speculated maybe there's a [bacteria] or there's some sort of microorganism that spew methane the way they do on Earth; but any kind of geologic activities such as volcanoes could be the smoking gun, could be the process that keeps replenishing the methane.
Steve: So the water would also be carrying some methane?
Castelvecchi: Right, they would carry methane as well as other compounds, such as ammonia.
Steve: So, speaking of water, closer to home I know that you attended a session about the Sulawesi Sea here on Earth?
Castelvecchi: Yes, there's been really spectacular videos and light shows of what the scientists have described as essentially the Amazon of the sea, or of the oceans. The Sulawesi Sea is between Borneo and other Indonesian islands and the Philippines. So, it's a region between the Pacific Ocean and the Indian Ocean, and as a consequence there's a mixture of diversity of life that resembles both; and it offers dozens of different ecosystems in the depth[s] of the sea. And these ecosystems had never been mapped extensively, and now there's an ongoing, actually, collaboration between U.S. scientists and Indonesian scientists. And this summer they've had two research ships on an oceanographic mission, and they've mapped the sea bottom and they've discovered dozens of creatures that may be new species.
Steve: Do we know more about Titan or the Earth?
Castelvecchi: Well, Titan has a very thick atmosphere, so I think that the surface of Titan hasn't been surveyed very well, but certainly the surface of Mars has been surveyed much more extensively than the oceans on Earth.
Steve: I know you also attended a session about light pollution. We know that light pollution is a problem for astronomers who are trying to observe what's going on out in space and we also know that light pollution affects some sea creatures—baby turtles when they hatch can be drawn in the wrong direction rather than going out to sea; they'll go to street lights. But you have some new information about the chemistry that's caused in the atmosphere by light pollution.
Castelvecchi: It's a really surprising finding. You wouldn't expect that city lights at night would have any substantial effect on the chemistry of the atmosphere. Even in a brightly lighted city, city lights are 10,000 times weaker than sunlight. [But] sunlight during the daytime is part of what causes the formation of smog. There are chemical reactions that are caused by light and helps create substances like ozone, which is really bad for you. But during the night one would think that light is so weak that that it wouldn't have an effect. But it turns out that there is a good kind of chemical in the air which would help break down the ozone and so reduce the pollution but keeping the lights on at night breaks down the good chemical and so, in the end, during the day, you end up having at least a few percentage points more of ozone than you would have otherwise.
Steve: Maybe an increase of about 7 percent, I see from their work.
Castelvecchi: That's the estimate, although the researchers warn that these findings are very preliminary.
Steve: But it's really interesting that something that no one would have suspected, probably, could still have this effect. It's an indirect effect but it could be, you know, a small but still significant effect on the increase in the ozone level.
Castelvecchi: And the research was done by flying an airplane over Los Angeles, but the effects could be a lot stronger in the winter in cities that have snow, because the streetlights get reflected by the snow, and then if there are clouds, the clouds reflect it back to the surface.
Steve: Right, they are actually acting as mirrors for all this light, so that the effective light is much higher.
Castelvecchi: Right, so but the good news is that perhaps reducing light pollution in addition to reducing the direct environmental effects of lights and in addition to helping us see the stars would also help us reduce atmospheric pollution. It also would help us reduce air pollution.
Steve: And also from the meeting, for the first time someone has been able to capture in the x-ray part of the spectrum what's going on in a lightning bolt. Now how do they do that and why is that important?
Castelvecchi: So this is really a first. Scientists have built, a dedicated x-ray camera, and they've triggered artificial lightning to take pictures in the x-ray spectrum as the lightning forms, as it comes down from the cloud. The very fact there is x-rays produced by a lightning is something that we've only discovered in recent years. It was pretty unexpected because lightning has a lot of energy, it discharges a lot of electrons, but the energy of the single electrons are lower than the energies, were thought to be lower than the energies of electrons that run, for example, in the ordinary x-ray machine in your dentist's [office].
Steve: Right, because if I go to the dentist and he takes an x-ray, you know, obviously there's not a whole lot of energy that went into that because it's being powered by the plug in the wall, and that's not a huge source of energy; whereas an individual lightning strike can have way more energy, you know, discharged in a fraction of a second then what's coming in from the wall at the dentist's office. But the individual electrons at the dentist, there are a small number of them, but they're at high energy whereas in the lightning strike we [have] a lot of electrons at a lower energy.
Castelvecchi: Correct, but it turns out that there's some electrons that are accelerated to really high velocities and they produce x-rays; and they even produce gamma rays, which are usually the wavelengths produced by nuclear reactions, by much more energetic phenomena.
Steve: So this is very interesting. Is it anything important or is it just intrinsically interesting that lightning has these qualities that, amazingly enough, we didn't about until now?
Castelvecchi: Well so far, it's just a demonstration of principle that it can be done; there's a very, very low-resolution video that has been taken, there's very, very few pixels of video that can show the x-rays coming from lightning. So far it's just a demonstration of principle—you can take these microseconds worth of video that show the x-rays and even the gamma rays coming from lightning. Whether that will help or not understand the physics of lightning remains to be seen.
Steve: But it's an interesting finding and that you're not just getting x-rays, you're getting gamma rays, which are really high energy.
Castelvecchi: Yes, and the physics of lightning it turns out, it's such a mundane phenomenon that we are all familiar with, but exactly what causes lightning, how it's triggered, how it propagates down to Earth is still a big mystery; the physics is poorly understood and anything that can help you understand the details of it may be a big help.
Steve: Davide, from the AGU meeting in San Francisco, thanks very much.
Castelvecchi: Thank you.
Steve: You can find short write-ups and video and photos related to these stories at our Web site www.ScientificAmerican.com and check out Davide's Web site sciencewriter.org He is even smarter than I thought, somehow getting sciencewriter.org as his URL.
Steve: Now it's time to play TOTALL……. Y BOGUS. Here are four science stories; only three are true. See if you know which story is TOTALL……. Y BOGUS.
Story 1: For a few days recently the Crab Nebula greatly increased its output of high-energy gamma rays.
Story 2: Redheads may have different anesthesia requirements than other people as they tend to have a lower pain threshold.
Story 3: Blue whales can take in close to a half million calories in a single mouthful.
And story 4: Snails are on the menu in France, and now they're in the security area at airports there, because they behave erratically in the presence of chemicals used in certain explosives.
While you think about those stories, let me tell you some big news: Scientific American's first app is out. It's free for nothing at the iTunes app store and it's called Scientific American Advances. It works on the iPhone, iPad and iTouch. You get material from the magazine including David Pogue's Technology column, Christine Gorman's Science of Medicine column and my Antigravity columns from the magazine, in addition to a lot of other articles from the print edition. So get it free at the App store—Scientific American Advances. As for TOTALL……. Y BOGUS your time is up.
Story 1 is true. The Crab Nebula's energy output is incredibly constant but it recently boosted its gamma ray output up to three times for a few days. Astronomers still aren't sure why. The crab is the remnant of the supernova that was seen on Earth almost a thousand years ago.
Story 2 is true. Studies have found that redheads do have a lower pain threshold and may need more or different anesthesia. A round up of the unique medical situation of redheads is in the British Medical Journal.
And story 3 is true: A blue whale can swallow an estimated 457,000 calories worth of food in a single gulp. That's according to research in the Journal of Experimental Biology. It is the biggest thing that's ever lived on Earth.
All of which means that story 4, about explosive sensing snails is TOTALL……. Y BOGUS. What is true, however, is that rats have been trained to identify tuberculosis-positive sputum samples. For more on that story check out the December 15th episode of the daily SciAm podcast, 60-Second Science.
Steve: Well that's it for this episode. Get your science news at www.ScientificAmerican.com, where you can check out John Matson's article on the Planet Hunters, a program that allows citizen scientists to join in the effort to find exoplanets. And follow us on Twitter, where you'll get a tweet about each new article posted to our Web site. Our Twitter handle is @SciAm and don't' forget to get the free Scientific American Advances app for you iPhone, iPad or iTouch. For Science Talk, the podcast of Scientific American, I am Steve Mirsky. Thanks for clicking on us.