The National Astronomy Meeting
We bring you the highlights from the Royal Astronomical Society's National Astronomy Meeting. We discover the top priorities for the next generation of space exploration, find out what the echoes of the big bang can tell us about the birth of the universe and explore gravitational waves - ripples in the very fabric of space and time. Plus, the importance of understanding the Sun, predicting the weather in space and the biochemical options for alien life.
In this episode
01:08 - The Royal Astronomical Society
The Royal Astronomical Society
with Professor Andy Fabian, RAS President
Ben - All this week, I've been at the Royal Astronomical Society's National Astronomy Meeting, held at Glasgow University, and this show contains just a few of the highlights of the meeting. To find out more about the Royal Astronomical Society, I spoke to their president, Professor Andy Fabian.
Andy - It's a society of astronomers, both professional and amateur based in the UK, but we do have an international following. There's about 3,400 members, so after the American Astronomical Society, it's the second largest in the world.
Ben - And what's the National Astronomy Meeting? What does that mean to you?
|The entrance to the Royal Astronomical Society, Burlington House, London © Mike Peel (www.mikepeel.net)|
Andy - Well, most of the RAS meetings take place in London, that makes it difficult for some people who live a long way away to meet, so we've had out-of-town meetings for some time. In 1992, we started National Astronomy Meetings where one university would try and organise something for a lot of people to come to. They've built and built, and now, we have 5- 600 people turn up for a week of astronomy.
Ben - Any particular reason you chose Glasgow University this year?
Andy - Well, they sort of chose themselves because there is the 250th anniversary of Alexander Wilson who was the first regent professor of astronomy there and he, amongst other things, did quite a lot of astronomy.
Ben - What do your members actually get out of the Astronomy meeting other than a chance to meet somewhere other than London?
Andy - I think a lot of networking goes on. People meet people that they don't see every day, different groups, you get to see and hear talks about different areas. There's this tendency for specialisation nowadays in science as in everything else, and it's good for people to hear about other branches of the science of astronomy. Because after all, we all are funded from the same pot - we complete for use of the same telescopes and instruments. It provides a better appreciation of what we're all doing as well as lots of interest.
Ben - We were reminded in the opening reception today of quite how important astronomy is, not just for blue sky science but for us in our daily lives.
Andy - Yes. It's surprising how many things that first came out of astronomy, have gone on to be things that are everyday. For example, Wi-Fi, which many people will have at home, is something that the patent is held by an Australian astronomer. If you think of the CCD, the Charge-Coupled Device which is the detector in most people's cameras, which are in most people's phones, they weren't invented by astronomers. They were invented by physicists, were discovered by physicists and indeed, they were looking for a storage device, an information storage device, and realised that they were light sensitive. The original ones were completely useless for making images. But astronomers early on realised the potential because they are a hundred times more sensitive than a photographic plate and they worked very hard in trying to perfect the CCD, which is sort of where it comes from.
In a way, what astronomers do is - they have to work on the detectors because we can't turn the light up. If you are making a film and it's a bit dark, you can turn the light up. Well, an astronomer can't do that. We can't change the brightness of our stars or our galaxies. What we have to do is take what we can and so, making our detectors more sensitive and more perfect is very important to us. So we put in that extra effort which makes these things then appreciated by others.
There are many scanners at airports, in medical physics, and in even looking at the human genome and things like that where devices that were originally developed by astronomers and now used to do lots of things in everyday life.
Ben - A great many of their delegates here will be people who've only just started a PhD or perhaps are a recent post doc. Do you think it's important for these people to get to spend more time with the established professors and the established researchers in order to find opportunities and to try and really shape the future of where astronomy is likely to go?
Andy - Absolutely. I think the young people are very important for the field. They are much more flexible in terms of being able to move from where the interest is. For example, extra solar planets, planets around other stars. A lot of students move in that direction. They move where the field is most exciting to them where they can see there's potential for development. Of course, you don't want everybody in the same field but I think it's important that they do interact with everybody, and of course, in science, it isn't something where you have to kowtow to people. A student can talk to a professor as long as they are being sensible about the science. They can talk to anybody and I think that there aren't any barriers with regards to hierarchy or age which is a very positive aspect of what we do.
Ben - And also, you might hear about opportunities here for the future study, or for funding that you may not have heard of elsewhere.
Andy - Yes, indeed. That's going to be very important for people who are trying to make their career, they need to assess things, they need to look at how other people have made their own career, and look at how they might copy them. Not to replicate exactly what that person's done because probably, there isn't such a slot. But what they can do is to see how people do things.
It's also very important to be able to talk about what they have done and scientists can't just do something and not tell anybody else about it. Scientists have got to get out there and tell their peers, other astronomers about what they've done. Later, they might want to talk to the press or the public after they've done something really significant. But generally, we need to tell each other what we've done and then everybody learns and everybody benefits.
Ben - And on that note, is there anything in particular that you're looking forward to hearing about this week?
Andy - Well, I'm looking forward to seeing how some of our new telescopes are producing new information. We've got new telescopes coming online. Astronomy is full of discoveries and surprises, exciting new facts coming along.
07:48 - Astronomy at Glasgow University
Astronomy at Glasgow University
with John Brown, Regis Professor and Astronomer Royal for Scotland
Ben - 2010 is an important year for astronomy at Glasgow University, as Professor John Brown, who holds the Regis Chair of Astronomy there and is also Astronomer Royal for Scotland, explained.
John - Well, the Alexander Wilson Regis chair appointment in 1760 was the first astronomy professorship in Scotland. There had been teaching of astronomy before that but it was quite a few decades ahead of Edinburgh and it was one of the earliest astronomy chairs in the UK. Astronomy has been growing here ever since so it's a big year for us and it's a great honour that the RAS has decided to bring their National Astronomy Meeting here for that purpose.
Ben - So it's obviously quite a milestone. What have been the big scientific achievements from Glasgow?
John - The biggest strength here , in the astronomy group area, has always been solar physics, you know, plasmas. Alexander Wilson studied sun spots and discovered that sunspots weren't flat things, the surface of the sun wasn't flat. It was hollow like a bowl and that was an amazing thing to find out because they had no idea then what the sun was. And he did all sorts of other things, Wilson, he invented new kinds of thermometers, measured the thermal structure of our atmosphere with measurements obviously to the fundamental theory of heat. He made specific gravity beads to measure the strength of alcohol and such, and the designed telescopes as well as the doing his astronomy. So he's probably the most outstanding person historically.
Since then there's been quite a number of others. There was a chap called Grant who created one of the largest star catalogues, the Glasgow star catalogue, in the mid 1800s. Then we had James Pringle Nickel. I'm not sure about his research but, if we had the internet and television, then he would've been world famous because he was a great, great populariser.
In More recent times we had William Smart. He did a lot of studies of the dynamics of stars going on in the galaxy. And then there was my mentor, Peter Sweet who was the ninth Regis Professor and the thing that he's remembered for are a thing called the Eddington Sweet Circulation; the way gases circulate inside stars. Quite important because stars burn hydrogen and turn it into helium and the helium sinks towards the centre of the star because it's heavier, but if the star is convecting enough, the helium can get lifted up again from the centre and that affects how stars of different masses change as they get older. So that was one thing and then the theory of how magnetic fields dissipate their energy in plasmas, called magnetic reconnection, that was what Peter Sweet did.
Ben - So, an excellent legacy. In what ways are Glasgow University researchers pushing the boundaries now? Where are they leading the search?
John - Well there's an Institute for Gravitational Research and they have continued this many decade long hunt to find gravitational waves, getting closer all the time, so that's exciting stuff. For the moment, that's not really pure astronomy as such although it's getting there. A lot of it is engineering, producing very exotic materials and mirrors. The astrophysics is being done in a certain sense and because they haven't yet detected anything, you can put upper limits on things. So we're getting close to true astrophysics.
In the astronomy group, theres' some very good cosmology going on, so large scale structure studies. Basic plasma physics is being done. We have a small plasma lab which is finding some medical applications as well as solar and astrophysical. The main thing I do, and that my colleagues do, is study high energy radiation from the sun - flares and the sort. We're moving forward in understanding how the sun produces very high energy particles which are related to the aurora and so on. When the sun erupts, it sometimes gives the earth a clobber with big gas cloud. We should be getting some quite nice northern lights displays over the next little while!
Ben - John Brown on the rich history and modern priorities of astronomy at Glasgow University.
11:51 - Cosmic Vision from the European Space Agency
Cosmic Vision from the European Space Agency
with Professor Mark McCaughrean, ESA
Ben - The National Astronomy Meeting gives people an opportunity to find out what others are working on and where the science might take us in the future. Mark McCaughran, from the European Space Agency or ESA, was at the meeting to explain ESA's Cosmic Vision of their plan to commission and support space missions over the coming years.
Mark - Cosmic vision is a programme which we put together in the last few years in the European Space Agency to provide some structure, some top level science guidance of the sorts of questions the community would like to see answered. Then we opened up an announcement of opportunity for people to actually propose actual missions against those questions in 2007. Space flight of course takes a long time to put missions together, but also, we've gone through a whole evaluation process to look at studying the mission, see what's feasible time-wise, cost-wise, and what the best science is. So we started with 65 missions in total and we're now down to the final 6 or 7. Out of which, we're still doing a shootout. It's kind of a technical shootout, looking at what's feasible on the right time scale. We want to get these things launched quite quickly - relatively, 2017, 2018. And so we don't want to do lots of technology development. You can think of crazy things that might take until 2030 to do and we want to get some missions in the pipeline because we have missions in this decade flying but we have a bit of a gap towards the end. And so, we want to get these things going.
Ben - So what were the questions that we think we want to answer?
Mark - Well, there are a whole range of questions starting from how does the sun work, how does the sun influence our lives every day, the weather in which we have space weather but also the weather on the surface of the planet. Of course, that's of great importance to many people as it relates to climate change. But then going to the other end of the universe, looking at the overall cosmological appearance of the universe, why is the universe the way that it is, how has the universe evolved to the state that it's in, what's the fate of the universe. But then there's all the things in between. How were stars born? How do planets get born around stars? How do they evolve? What are their chances of finding the conditions for life and maybe even life elsewhere? And then in our own solar system, is life unique in the solar system? Can we go to Mars? Can we go to the oceans of Europa under the ice crust there and are the conditions right for life there? So it's a kind of an overarching set of science questions. Many of the missions will approach many of those questions.
Ben - And so, was it split evenly? Did you say "we have this much resources, we have this many questions. We want to make sure we give X resources per X question."
Mark - Yeah. That's a very good question and in fact, more traditionally rather than per question, you would've seen it allocated in the past per discipline. But there was no precondition set on this. In fact, this time around, the astronomers are in the ascendant, they've got out of the M class missions, the medium class missions we're studying, they've got 3 of those, 3 out of the 4, and 2 of the L class missions, the large missions, those are astronomy or astrophysics related. That sounds like the planetary people are doing very poorly but of course, they've got other things which they're doing including going to Mars with NASA. That's not something that was in the cosmic vision process. That's a separate program at ESA. So the whole Martian exploration is going on in tandem in parallel.
Ben - So what's the difference between a medium class mission and a large class?
Mark - The amount of money is different between the two of them and originally, the M missions started off at 300 million Euros brought in from ESA. We had to look at that again and now, we think that to make sense out of those missions, the science goals that they propose as asked but also that the community felt were the best ones, probably going to cost us about 450 million. We expect then money to come in from the member states of ESA as well, European countries who contribute building bits of the payload, building parts of the instrumentation, maybe roughly 150 million more so about 600 million for one of those. The L missions have a contribution from us of about 650 million, but they will be actually - all three of those which we're looking at at the moment would be in tandem with United States, Japan, and other collaborators. And so, those are much bigger missions overall, up to 2 billion, for example, for our Jupiter mission, EJSM. So, the amount of resources is larger there, but also, we expect them to do more stuff. So the M missions are supposed to be very focused science goal experiments if you like - let's pick one question, let's get an answer to it, let's do it as well as we can. The Ls are generally more observatory style missions where you're going to look at a whole broad range of questions with a suite of instruments or go and do outer solar system exploration which is very expensive to do. It takes a long time to get there.
Ben - And so, what are the ones that you've considered? You said you've whittled it down to a short list.
Mark - Well we have on the M side, the medium missions at the moment, we have 3 full M's if you like. They're full scales ones. One is called Euclid and that's a dark energy mission. It's going to be looking at this mysterious stuff that appears to be accelerating the universe rather than the universe slowing down as you might expect. The second one is a mission called Plato and Plato is designed to go and look for planets around nearby stars and it does it by watching for so-called transits. If you get the alignment just right, a planet orbiting a star will go in front of the star as seen from your telescope or from the earth and it will make the brightness of the star drop very slightly for a day or so as it transits across for a few hours. So that's 2 out of 3. Third one is solar orbiter, looking at the sun and looking how the sun impacts our environment, and to get the best possible view on the sun, you want to get much closer to the sun. And so, rather than sitting out at the distance of the earth like our current mission, Soho does. Solar orbiter will be going into just a third of that distance. So a much closer in. But also, it's going to rise up above the plain of the planets so we can look down at the sun. Not exactly from above but from a high enough angle that it can see what's happening at the poles of the sun. So those are the three big M's and the last one is a thing called SPICA. And SPICA is actually a Japanese mission and it's a lot like our Hershel space telescope which we launched a year ago. But the big difference to Hershel which is doing fantastic stuff, SPICA is designed to be actually cooled down. The telescope will have refrigerators on it and cool the telescope down to just 6 degrees above absolute zero, so minus 200 - and see if I can do the math - 267 degrees C. And that reduces the background, the emission of telescope itself, and it makes all the instruments much more sensitive. So it's like a super Hershel and we would be contributing the actual telescope plus one of the instruments. So those are our four M's.
Ben - And the L class, the large missions?
Mark - Well there, we have three missions which are effectively all in collaboration with the United States with NASA. One of them is called EJSM, the Europa Jupiter System Mission, going off to Jupiter, studying Jupiter in great detail, but also, flying two orbiters, one around Ganymede and one around Europa. And that's to study those very interesting moons. Those moons have water oceans, we think, under very thick crusts of ice and so, very interesting environments potentially for life elsewhere in our solar system.
The second one is called IXO, the International X-ray Observatory, and this is a big collaboration again with NASA and we're joining forces to build a much bigger telescope which will collect much fainter x-ray photons from the high energy sky, from places like black holes, the extreme environments in our universe where very violent events take place.
Then finally, we have a mission called LISA and LISA's slightly less conventional than the other two. LISA is designed as a mission to detect gravitational waves. So the influence of gravity spreading through the universe from violent events like black holes merging, very high energy events where as the material is converted from matter into energy, you get ripples in the space time. LISA does this in a very interesting way. It puts three space crafts in the solar system, 5 million kilometres apart in the triangle and as these gravity waves pass through the LISA constellation, the three arms between the space craft will change length very slightly as the space time is distorted. And we have this incredibly high precision measurements, measuring this 5 million kilometres to nanometres. So 10-9 of a metre over 5 million kilometres and we do that on three arms simultaneously and by actually seeing how the arms change length, differentially, we can even work out where in the sky that object is. We can go and find it and say, "Right there, at this moment in time, two black holes have just merged and we see this fantastic ringing signal, this big "bong" as the two black holes merge together. So LISA's really odd. Of course, it's also predicated on something we've never detected which is gravity waves.
Ben - They all sound incredibly interesting. They're all answering really important and interesting questions. How do you choose which ones to support?
Mark - Well fortunately, we don't. That's why we have a whole community of scientists who we have in our advisory structures and we consult them and we try to place science foremost. These are very difficult decisions and people have to struggle with their own conscience sometimes and say, "Well, this is the one I really like because this is the area where I work in. I can take a big enough picture and see that this other mission is the one we should be going for." So we have a whole series of committees of working scientists - active people who make recommendations. They pass those recommendations to us and we try to look at them in terms of the programmatics, how long will it take to build, who will we collaborate with, the technologies we need to develop that we don't have yet. So fundamentally, it's a whole series of difficult decisions to make. All of these things, we would like to do. So we're always rejecting good ideas but in fact is a very positive process because it means that you have a robust check that you're doing good stuff.
Ben - Mark McCaughran, explaining ESA's Cosmic Vision.
21:51 - Probing the Origins of the Universe with CMBR
Probing the Origins of the Universe with CMBR
with Professor George Efstathiou, Kavil Institute for Cosmology
Ben - Astronomers and Cosmologists seek to understand the origins of the universe, but as this was billions of years ago, we're left with very few clues as to what actually happened. One of the big clues is the Cosmic Microwave Background Radiation, as Cambridge University's Professor George Efstathiou explained.
George - The Cosmic Microwave Background Radiation is the remnant radiation from the Big Bang. And as the universe has expanded, this radiation has cooled and is now observed as a background radiation with a very low temperature of 2.3 degrees above absolute zero.
Ben - So it pervades the entire universe and shows us that at some point in the history, the universe, it was very hot and very dense.
George - That's right. The discovery of the microwave background was discovered in 1965 and once that radiation was discovered, it was really incontrovertible proof that the universe started off with a very hot dense state.
Ben - And how do we study it?
George - We can study it by observing the radiation at microwave wavelengths. So there have been a range of experiments and missions since the discovery of the background radiation. But it was realized very early on, as soon as the radiation was discovered, that the structure that now produces galaxies and classes of galaxies that we see in the universe today would have imprinted tiny little temperature variations on the background radiation. And so, physicists and astronomers started a search to discover these fluctuations and they were discovered in 1990 by the COBE satellite. These fluctuations are very important because we see them at the time that the universe became neutral. This occurred when the temperature of the background radiation was around 10,000 degrees and the universe was only 400,000 years old. So we see the universe as it was 400,000 years after the Big Bang. But the fluctuations that we see are faithful representations of what happened 10-35 seconds after the Big Bang and that's the real interest that cosmologists have in studying these fluctuations because it tells us about conditions in the ultra, ultra early universe.
Ben - And so, can we use it to work out some of the physics that was going on back then?
George - That's right. By studying these fluctuations, we can probe physics at ultra high energies, 10 to 15 orders of magnitude higher than the energies achievable by the large hadron collider. The physics of those high energies is really not at all well understood and it could be very, very different to the sort of physics that we know about. And that's what makes it really fascinating because a theory like that would have maybe 9 or 10 spatial dimensions. And these dimensions that we currently don't see, at those very early times, would've opened up. And so, it's possible that we could see signatures of higher dimensional physics by studying the background radiation.
Ben - Relatively recently, the Planck mission has set out to try and study this in more detail. What are you hoping to use that for?
George - Planck was successfully launched last year and it is by far the most sensitive space probe designed to study these fluctuations. So we will get much, much better images, of a higher angular resolution with much higher sensitivity that have ever been achieved before. And we're also measuring the polarisation. In this background radiation, the fluctuations are slightly polarised. They're polarised at a few percent level and Planck has sensitivity to polarisation so we expect to create an accurate picture of not just the distribution of temperature but the distribution of polarisation. That's very important because gravitational waves generated in the very early universe can produce a specific type of polarisation pattern which we may detect.
Ben - So what's the really big question that we're trying to answer?
George - We know very little about the physics of these very early times. What we would like to know is what actually happened very, very close to the Big Bang, not just in a sort of conceptual way, but actually really probe the structure of the Big Bang. What we think happened is that very close to the Big Bang, the universe underwent a period where it effectively expanded faster than the speed of light. So we called this a period of inflation. It's a very attractive theory. It is not a well-founded theory in terms of physics yet, so we don't understand the mechanism, we don't understand any of the details. What we hope to do with Planck is to get enough information that we can actually get a handle on what actually happened. Did the universe really go through an inflationary phase of expansion? What was the physics responsible for inflation? How were the fluctuations generated? What was the energy scale of inflation? These are the sort of questions that we hope to answer.
Ben - George Efstathiou on how we can use the leftover radiation from the Big Bang to probe the early universe.
26:56 - Observing Gravitational Waves
Observing Gravitational Waves
with Professor B. S. Sathyaprakash, Cardiff University
Ben - In 1916, Albert Einstein predicted that Gravitational Waves, these are ripples in the very fabric of space and time, must exist. We now know that they do, but we still can't observe them directly. Professor B. S. Sathyaprakash (who prefers to be called Sathya), from Cardiff University, explained more about these mysterious ripples.
Sathya - Gravitational waves are really a consequence of combining Newton's gravity with Einstein's special theory of relativity. In Einstein's special relativity, he's sure that nothing can move at speeds greater than the speed of light. But according to Newton's gravity, gravity will have to travel instantaneously and that's impossible according to Einstein's special relativity. So in a way, when you marry Newton's gravity with Einstein's relativity, you have to have gravitational waves. So in a few more words, gravitational waves are simply ripples in the very fabric of space and time which travel from their sources at the speed of light.
Ben - So, light does it come in photons or is it a little bit more complicated?
Sathya - It's actually not so much more complicated at all because light, we can think of them as particles only when the wavelength is tiny, which means energy is extremely high. When we are talking about gravitational waves, the wave length is extremely large. If you have very high energetic gravitational waves, we would probably think of them as gravitons which are the names given to particles of gravitational waves. But the correct way of thinking about them is really that they are ripples. You know, you throw a stone in a pond that produces ripples outwards and similarly, there is an exploding star that sends out ripples of gravity and those are gravitational waves.
Ben - Are they entirely theoretical or have we experimental observations of them?
Sathya - Until about 30 years ago, they were completely theoretical and in fact, even Einstein is supposed to have said, "Oh, they are an artefact of my theory. There is really no way to generate them or detect them." But lo and behold! Astronomical observations have actually given us a system. Namely, it consists of a pair of stars. They are very, very dense stars and they're going around each other. What would happen in Newton's law of gravity is that they will go on like that forever, not changing their period, not doing anything much. Whereas in Einstein's theory of gravity, they're churning the space time in which they are moving and therefore, they're generating gravitational waves. And gravitational waves carry energy and they carry rotational energy from the system and that energy has to actually come from the rotational energy which means that the period of the binary is going to decrease. This has been observed. The agreement between observation and theory is so wonderful, there is no other explanation for the decrease in period other than gravity waves. So we know for sure gravity waves exist.
Ben - So is there or will there be a direct way of observing them rather than just observing the impact that they have?
Sathya - I think you put it very, very rightly. There is no way of concluding from this binary that we have directly observed gravitational waves. We have to find a way of detecting them indirectly and currently, world over, there are many gravitational wave detectors that are currently being built, and they are actually taking data and this data is being analysed. So we may or may not detect them now, but they're also being upgraded. Upgraded to the level where we are guaranteed of detecting gravitational waves within the next 5 to 10 years or so.
Ben - What can we do with them once we measure them? What can they tell us about the universe?
Sathya - We might be able to learn a lot more about the way the universe works especially about what we call the energetic universe, the universe in which there is so much energy that you can't see the object in photons. You can't see the object in radio waves or light and that's because it shrouded with a lot of matter, very dense matter, and the only way we might be able to learn about them is actually by observing gravitational waves. One example that comes to mind immediately is a pair of black holes. Now black holes are really dark only in light and radio waves, etcetera, but they're not dark in gravitational waves. If you compress a black hole, energy that you put in will be emitted in gravitational waves and that black hole will regain its original shape. Now the way you can compress is to take another black hole and hit it! Hit this first one with the second black hole and we don't need to really do that ourselves. Nature provides for us what are called binary black holes. These are two black holes that are going around. Originally of course, both of these black holes were ordinary stars. They evolved and they were massive, and when they went through their evolutionary stage, they became black holes and they are going around each other and they reduce in size as in the case of binary neutron stars. Eventually, the two black holes will collide and in the collision process, you can actually see these black holes in the gravitational window.
Ben - So gravitational wave astronomy could let us observe things that we've never been able to see before. That was B. S. Sathyaprakash, from Cardiff University.
32:51 - The Science of the Sun
The Science of the Sun
with Dr Lucie Green, Mullard Space Science Laboratory
Ben - There were a number of discussions on Solar Physics during this year's National Astronomy Meeting, so I met up with Lucie Green, from University College London, to find out what it is that's so interesting about our nearest star.
Lucie - There are lots of interesting aspects to studying the sun. On the one hand, it's our local star so it has a very big impact on us here on earth, and we're interested in studying how exactly it impacts us. But on the other hand, it's interesting as an astrophysical object in its own right and in many cases, when we study the sun, we actually take that understanding and then apply it to other areas of astrophysics.
Ben - So what are the things that we're trying to learn from it?
Lucie - One of the things that we're most interested in is understanding how the magnetic field of the sun changes. So, the earth has a very strong magnetic field but the sun has a much stronger and much more interesting magnetic field, and that in fact, it governs much of the activity that happens in the sun. For example, the work that I'm interested in is looking at how the magnetic field in the atmosphere of the sun evolves and how it leads to big explosions that we call solar flares and eruptions of magnetic field which we called coronal mass ejections.
Ben - And what can studying our closest star tell us about other stars? Do we think it's fairly typical?
Lucie - We do think it's fairly typical. But actually, when you think about other stars, it could be that our sun is fairly boring. The sun is fairly small really when you compare it to other stars and the activity which happens, these explosions and eruptions, even though it's really interesting to solar scientists and people on earth, it kind of pales in comparison to maybe explosions that happen on other stars. But it still is a good benchmark because we can study the sun in detail, we can resolve the surface. We have lots and lots of light of all different wavelengths to play with, and we can learn a lot. One interesting piece of research that has happened recently has taken a model of coronal mass ejections, so these eruptions of magnetic field from the sun's atmosphere and has applied it to jets which are seen coming from the accretion discs of black holes, and that's a really nice transfer of understanding. So we can look at the coronal mass ejections and we can look at the eruption, we can think about the configuration of the magnetic fields for example and then see if those models match with the observations of black holes, and in this case, they did.
Ben - How is it actually studied? What sort of tools do we need?
Lucie - We use a lot of tools when it comes to studying the sun. We can look at maps of the magnetic field at the solar surface and that's very, very important. And we can get some idea about the three-dimensional field very low down in the sun's atmosphere. But at the moment, we're not able to measure the magnetic field high up in the sun's atmosphere, and that's partly due to the fact that the gases in the sun's atmosphere are incredibly hot. So they smear out the signature of the magnetic field. But actually, a lot of the interesting stuff happens in the magnetic field high up in the atmosphere. So that's exactly where we want to get the information. So, in the absence of having a direct measurement of the magnetic field, what we can do is try and infer what's happening and we can do that by taking observations of the sun and x-ray radiation and also, extreme ultraviolet radiation. And the emission of these wavelengths actually traces out the shapes of the magnetic fields and gives us some sense of what's happening.
Ben - So going back to these enormous ejections of material from the sun, the coronal mass ejections, these have quite a big impact on technology here on earth and our satellites, but what does actually cause them?
Lucie - Well that's one of the questions I'm working on as a researcher and I think it's one of the most important questions in solar physics. So, what we're looking at is understanding how the magnetic field evolves. It all comes down to the magnetic field. The energy which is required to power these events must come from energy stored in the magnetic field. So by looking at the shapes, the configurations of the magnetic field, we can start to understand how much energy is stored, and we can also start to understand what causes the magnetic field to suddenly erupt in the first place. It must lose its equilibrium. So, the structure exists in the solar atmosphere on the time scale of maybe hours, days. We're not exactly sure, but it does exist and it's stable, and it's happening. And then something happens to cause it to erupt up and escape the huge gravitational pull of the sun and that's the moment that we're interested in understanding.
Ben - So what's the next stage for you?
Lucie - The next stage is to continue working with Hinode space craft which is a Japanese mission on which we have a UK led telescope. And what we're going to do is use a very recently discovered signature of a magnetic configuration that we call a flux rope. A flux rope is a bundle of magnetic field lines which is very good at storing energy in the solar atmosphere. And using the Hinode space craft, we can understand where these flux ropes are forming and we can look at them up until the point of eruption. So the plan is to gather a lot of case studies and put the information together to find out at what point this flux rope becomes unstable and erupts as a coronal mass ejection.
38:09 - Forecasting Space Weather
Forecasting Space Weather
with Dr Jim Wild, Lancaster University
Ben - We hope to see lots of the Sun in our weather forecasts here in the UK - but out in space that may not in fact be the case. Here's Dr Jim Wild, from Lancaster University...
Jim - Well, space weather is the changes in the space environment quite close to the earth that result from primarily solar activity. So, obviously everything on earth is driven - all energy sources on earth ultimately start off at the sun. But the sun's quite dynamic on a lot of timescales. So from minute to minute or hour to hour, year to year, century to century, the amount of activity can change. It's shorter term time scales that we refer to as space weather, in the same way that changes in the atmosphere in the amount of rain from our own day to day we think of as weather on the ground. So space weather is usually driven by the sun, for example, if you have a large flare or coronal mass ejection, that energy is transported through space and will arrive at the earth some time later in a variety of different forms and interact with the space environment around the earth, the magnetic field of the earth, the atmosphere of the earth, and it will produce some effects on the ground or in earth's orbit that we can measure. Actually, we tend to think of space weather as affecting man-made technology, so space weather kind of presents a bit of a hazard to man-made technology on and above the surface of the earth.
Ben - Just like with normal weather, do we try and predict it?
Jim - We do try and predict it. In fact, the ultimate goal would be to be able to predict it. It is quite difficult. Just like it is with normal weather, it's a bit easier the closer to the present that you get. So at the moment, we're kind of at the stage where human beings can do what we call "Nowcasting." Instead of forecasting what's coming, can we actually just say what the status of things is now? So the "nowcasting" at the moment as we're sitting here on this bench in sunny Glasgow is that it's sunny and it's not raining, and a "nowcast" globally would be able to say that to about the entire surface of the earth for the regular weather. If we think about space weather, the "nowcast" would be how much radiation is coming from the sun, how many energetic particles are coming from the sun, what's the status of the earth's atmosphere, the upper ionosphere that we use for radio communications, the radiation belts, how energised are they, how much energy is coming in to the auroral zones that causes the northern lights. All those kind of effects.
So, "nowcasting" is the first stage and we can sort of do that. We can make measurements in real time even from spacecrafts that are upstream of the earth. So, we have sentinel spacecrafts that are located about 250 earth radii upstream of the earth and they sit there and sample solar wind that's on its way towards us from the sun. So we know what's coming and that gives about an hour's warning. We can take pictures of the sun, so that can tell us about things that are going to take about three days to arrive at the earth. So we can start to forecast but it's still quite crude. We're at the stage of being able to say in the summer, it will be generally warmer than the winter and there's probably a big storm due in a few days but it may or may not strike. We're not quite sure yet. So it's still quite ballpark at the moment.
Ben - So how is it studied? What tools do we need to use?
Jim - There's really a whole suite of tools. So, we start all the way from upstream of the earth. So if you imagine you have the sun 93 million miles away. The material leaving the surface of the sun, so physical material, charged gases that we call plasma, that generally takes a few days to get to the earth. So we have a spacecraft that's upstream of the earth that's sitting in this solar wind that can taste and smell if you like. It can see the composition of the solar wind, how energetic it is, how much of the sun's magnetic field that solar wind is dragging out with it. so we have space-based tools that are quite a long way from the earth. Then coming a bit closer, we have an international flotilla of satellites orbiting the earth right down through radiation belts and then getting to quite low altitudes above the surface of earth to a few hundred kilometres above the surface of the earth. And then on the ground, we have whole suites of radars that study the atmosphere, the upper atmosphere, and the ionosphere so that's the electrically charged parts of the upper atmosphere. That's typically from a few 10s to a few hundreds of kilometres. Then right on the ground itself, we have magnetometers. So they're measuring small changes in the earth's magnetic field that are being imposed by the interaction of the earth's magnetic field with the space environment. And so, we have everything from little boxes on the ground that cost a couple of hundred quid to multi-billion pound satellite missions which are 250 planetary radar upstream of the earth.
Ben - If one of the things we're hoping to monitor or prevent or at least be prepared for is damage to our technology by the space weather, isn't it a bit of a risk, putting a multimillion pound satellite between the sun and us?
Jim - Certainly, the satellites that are upstream and monitoring the space weather environment, they are outside of the earth's protective magnetic field to begin with and the protective barriers of the earths atmosphere. So they are in quite harsh radiation environments and they're built to withstand some of this. But you can certainly see when we have large events that the spacecraft do take a bit of a kicking.
There is a very famous event, or to scientists, it's very famous. In October 2003, there was a large flare and accompanying that flare was a coronal mass ejection, a big explosion on the solar surface which stream out about a billion tons of energised electrical charged plasmas, these electrical charged gas which travelled towards the earth at about a million miles an hour. So it took a few days to arrive at the earth.
So when it arrived, it was about October 31st. It was a Halloween storm. Scientists are wonderfully imaginative when it comes to naming these things. But that passed by several spacecrafts on the way and you could see this thing coming, you could see it coming in the images, you could see the blast, and then you could see huge amounts of noise and radiation damage to the spacecrafts. So actually, the spacecraft's solar cells which are obviously designed to absorb radiation and create electricity actually absorbed huge amounts of damaging radiation, and it knocked a couple of months of the expected lifetime of those solar cells. So yeah, they're in quite an extreme environment, but it's kind of like, you have to have a thermometer to put in to that jug of hot water to measure how hot the water is, so you need to build something that'll last.
Ben - How do you adapt a spacecraft to be able to cope with those conditions?
Jim - The ones that go upstream, they're generally built to be radiation hard so the components they used are built to withstand radiation environments. So they're quite different to the kind of components you would buy if you were building a radio set yourself. They're radiation hardened bits of kit. For stuff that's a bit closer to the earth, what you tend to find is that they get some shielding naturally from the earth, but they can still be exposed to damaging radiation doses and especially electrically charged particles because these blitz through semi-conductor chips and they change ones into zeros which can be a very bad thing in a circuit if it controls a computer onboard a spacecraft. So what we can do is those spacecraft can be put into much more safe modes, they can be powered down for example or told to disregard any strange commands in the next few hours or shunted into even slightly different orbits in extreme cases. But of course, the trick there is knowing these things are coming and that's where the forecasting and nowcasting comes in because we really want to be able to study what's coming and be able to say, "Okay, spacecraft needs to be a bit aware now that something interesting is going to happen."
And as well, it's not just spacecraft in orbit, going back to a very common earth analogy, you wouldn't launch a ship - a brand new ship - into a typhoon in the same way that a spacecraft - whether it's a communication satellite or a scientific mission, you wouldn't launch that into a very damaging or extreme space environment. So what you generally want to know is, is it quiet at the moment and is it likely to stay quiet for the next couple of days, so my spacecraft can get launched into some regularised orbit before any bad weather hits.
45:03 - The Wide Angle Search for Planets
The Wide Angle Search for Planets
with Professor Andrew Collier Cameron, University of St Andrews
Ben - This year, Professor Andrew Collier Cameron, from the University of St Andrews, announced some surprising discoveries from the Wide Angle Search for Planets, or WASP project.
Andrew - We've announced the discovery of nine new transiting planets from the WASP project which brings our grand total up to about 28 and among those, we've also done additional observations aimed at measuring the tilt of the planet's orbit relative to the star's equator. It turns out that two of the nine have orbits that are so strongly tilted that they're actually going around the star in the opposite direction to the stars spin - which is a bit of a surprise. So, these two odd balls join another three previously discovered WASP planets to which we've applied the same technique and which we've also found are going around in the sense opposite to the star's spin. Now, there's another group who've also found a 6th retrograde planet like this and this brings the grand total up to six planets out of 27 whose orbital tilts have been studied so far, that are going around in the wrong direction. So, these close orbiting planets which previously everybody expected would be orbiting neatly in the star's equatorial plane actually turn out to be all over the place.
Ben - Why was this result so unexpected?
Andrew - It came as a surprise because for many years, we've always considered that hot Jupiters form in the cold outer reaches of the planetary system, much as the gas giants in our own system did, but that they underwent unbalanced forces in those discs which very rapidly, within a few million years, drove them in through the disc, and then left them parked in orbits very close around their stars. The trouble is that the star itself has formed out of the material from that same disk. So, rather like a ping pong ball sitting on the plug hole, you would expect it to be spinning in the same direction as the water is going down the plug hole. So to find a planet going around in the opposite direction suggests that it's been through some violent interaction with something else which is completely reversed its motion.
Ben - We tend to have the idea that the early life of any solar system is quite violent anyway. There's lots of interactions and lots of collisions. Why should we be surprised that we're seeing evidence of violent action in other solar systems?
Andrew - Well, the violence that happened in our own planetary system all happened in more or less a single plane because it was driven by Jupiter and Saturn, having formed in the outer reaches of the solar system and there's a beautiful theory whereby, they migrated very slowly in towards the sun. They never got very far but they reached a point where Jupiter was going around the sun twice for every once that Saturn went around, and that played dynamical havoc with the rest of the system. It pushed Uranus and Neptune from relatively small orbits out to where they are today and at the same time, it sent planetesimals bombarding the inner solar system and bodies like Mercury and the moon still bear the cratering record of the so-called late heavy bombardment which happened about 700 million years into the solar system's history.
But the sort of violence we're talking about here is of the kind where something like that, Jupiter or Saturn event might have happened, but it was so violent that it actually resulted in one planet being thrown clean out of the system, and the other one stranded in a highly eccentric orbit. Even that might not be enough to give you a backward planet and there is a third flavour of the theory which invokes something that's called the Kozai mechanism. Now this was actually originally developed to explain why some comets have very highly tilted orbits because of the influence of Jupiter going around the sun. Now if you scale that picture up and you imagine a star that has say, a distant low mass, stellar or brown dwarf companion and if you've got a perfectly normal Jupiter, you do computer simulations and you find that the orbit of the Jupiter suddenly begins to oscillate and become very, very elongated. The planet passes very close to its star and moreover, the orbit begins to tumble. The upshot of this is that every time the planet goes close to the star, it raises a tidal bulge and that gradually leads to shrinkage of the orbit and the eventual formation of a hot Jupiter, but a hot Jupiter that isn't necessarily in the plane of this star's equator. It can be parked at just about any angle at all and that is actually remarkably close to the picture that seems to be emerging from our observations.
Ben - So if these systems have had a rampaging gas giant flying about at all sorts of angles throughout their history, would we expect to find other planets there?
Andrew - It would be very difficult to find terrestrial planets because the old theory whereby a Jupiter migrates in through the disk requires that process to happen while the disk is still there, obviously. And since the lifetime of the disk is only about 3 million years, then you have absolutely no trouble forming terrestrial planets out of the debris that's left in its wake. Now we think from meteoritic evidence and radio isotope evidence and from astrophysical evidence, looking at other planetary systems, that it takes about a hundred million years for terrestrial planets to form. So, Jupiter-like planets form very quickly but earth-like planets form very slowly. So, if you have a process that takes hundreds of millions of years as this Kozai mechanism does, then as you say, the rampaging gas giant is going to disperse all of those planetesimals long before they have a chance to build a terrestrial planet. So, if this is the correct picture for the formation of hot Jupiters, then we would certainly expect that hot Jupiters and Earths don't mix.
Ben - So the search for habitable planets may have to ignore systems with a hot Jupiter in place. That was Andrew Collier Cameron, from St Andrews University.
51:16 - Building an Alien Biochemistry
Building an Alien Biochemistry
with William Bains, Cambridge University
Ben - Finally this week, a new way to think about the search for extra terrestrial life. Here's Cambridge University's William Bains...
William - I come at this from a very indirect historical route but in summary, I became interested in astrobiology because of some particular chemistry I was doing and as a biochemist, I started out by asking, "Well, what is life and what is biochemistry?" from a very fundamental level. And that seemed to be quite a productive line of research to follow. Most of the material I was reading about the origins of life was written by chemists who looked at it chemically or astronomers who looked in terms of creating planets. They won't look at it in terms of somebody who's been used to trying to discover new drugs, looking at organisms that are very complicated, very poorly understood collections of stuff. So I thought I'd start with that and see what the stuff is and what could we say about life from the very basic level, via a basic understanding of the process of living.
Ben - We obviously have a very good example of life here on earth. It's very diverse, it's very interesting but in a way, biochemically, that sort of makes it just a sample of one. Is it possible that this blinkers the way that we do look for life?
William - Well, it certainly does. It has to, doesn't it? We look around life on earth and it's so powerful, it's so diverse that it's very easy to be overwhelmed by that. There is no other possible way you could put life together. Actually, I was talking to another conference attendee a bit earlier. One of the great advantages as a biochemist talking to physicists, is that they think about things completely differently. This physicist said "well actually we don't have any samples of life at all because you need to discount the earth because of observer bias". So once you discount the earth, how many examples of life do we have? We might have life on Mars but we don't know anything about it. Apart from that, we have no examples of life at all. And if you start from that position, you realise we don't really know much about what life would be like outside the earth at all. So, we're both overwhelmed by the fact there's life here but also, we're conned into thinking that we are typical. We might be. We've no idea, but we don't know.
Ben - So, do you have to look at this, try and be objective, and look at the possible biochemical combinations that we could have that could create life?
William - Absolutely and that's the overall thrust of the research that I'm doing. It's a really difficult problem and I don't pretend to have done more than nibble at the edges of it. But yes, the idea is to try to think from a chemical basis what sorts of chemistry could you put together to do the sort of fundamental things that life does.
Ben - We have, from years of studying chemistry, a very good idea of how different molecules will react together, what possible combinations we have. But it very quickly builds up into an enormous network of possible interactions. How do you whittle this down to the ones that could be plausible for life?
William - Yeah. It's a huge problem in combinations of options. There are two answers to that. The first is there are some very general rules you can apply. So, life has to work in quite thick solutions. If you look at the difference between a fish and the sea, the fish is full of chemicals, full of stuff. Protein, metabolites, all sorts of things, and the sea is clean. So, life is going to have to be dissolved in something. So, if you try to build life out of chemicals that simply don't dissolve, it's not going to work. They have to be reasonably stable. So, trying to build life out of molecules that will instantly react with water and expecting that life to work on earth just isn't going to work. And there are a number of slightly more indirect and sophisticated filters you can put in but the same sort of basic logic. The difficulty is, does that then leave you with one or two possibilities of biochemistry or half a dozen different types of possibilities, or does it leave you with hundreds of billions of possibilities? At the moment, we have no idea.
Ben - Is it actually easier to look at a planet or a moon and say, "Well this is the chemical environment we have. These are the options for life?"
William - That's what I'd hope. That's the overall aim to say, not only are these the options for life but these are the likely signs that that sort of chemistry is going on in that environment. And then of course we'd look for it. This is a fascinating intellectual puzzle but there's not much point doing it unless it comes out with something you can test, something that the astronomers can look for in a spectra or the spacecraft can look for when they land.
Ben - I understand that you have been considering Titan as an option and looking at the chemistry on Titan?
William - Yes. Titan is the coldest body in the solar system which we know has definitely got liquid on it. The surface is incredibly cold. It's only about 90 Kelvin, so 90 degrees above absolute zero. It's definitely got ponds of liquid methane and ethane mixture on the surface. In some ways, it's like earth but of course, the chemistry is bound to be completely different. And that's why I've chosen it. Not because I think there's likely to be life there but because it is an extreme example that pushes your assumptions and therefore says, "Can we say anything sensible about that?"
Ben - So, if life does has to have solubility involved, then it must be a series of chemicals that are soluble in this liquid methane and ethane. Do we know of any that would fit the bill?
William - We know of a few very small simple molecules definitely. I mean, liquid methane and liquid ethane are important to the gas industry so people have measured the solubility of things like carbon dioxide and water in liquid methane. People have measured the solubility of a number of small molecules in very cold solvents, so, liquid methane, liquid nitrogen. So we've got some data on what is soluble, on the type of molecule that's soluble. They all tend to be small and this is a problem for designing a biochemistry because you do need things that will dissolve and you need lots of different molecules that dissolve. And whether we can get enough different types of molecule dissolved, there's still hope in question.
Ben - What are the core jobs that we need biochemistry to do in order to get what we think of as life?
William - Oh Gosh! Well, you have to be able to have some sort of large molecules that can act as catalysts. This isn't just to make the chemistry happen fast. It's also to make sure that the chemistry goes in the right direction. You need some sort of information storage. Life works from an internal plan, a coded description. This doesn't completely describe life but life emerges from that code. Clearly, life has to handle energy. It needs energy to make something happen to drive the chemistry forward in the right direction. You need structural components. You need to contain the chemistry in some sort of bag or sack. The problem we're stating, the requirements for chemistry in this terms is incredibly general. Somebody came along and say, "Could you do these things with the chemistry of silicon?" And the answer is, "Not under terrestrial conditions." Water, in particular, just dissolves most silicon chemicals and turns the silicon back into sand. But in Titan conditions, where the water is all completely frozen out as rock, and you're dissolving it in liquid methane and liquid ethane, the answer is possibly. Do I think there's silicon base life swimming around in the lakes of Titan? Extremely unlikely, but we can't yet rule it out.
Ben - Cambridge University's William Bains on a biochemical approach to finding life on other planets.