Astrophysicist Chris Lintott is a researcher at Oxford University, co-hosts the Sky at Night programme and is involved in a number of fascinating citizen science projects. More locally, he presented a cracking review-of-the-astronomy-year lecture at Notts Uni recently.
NSB was hugely chuffed to have the opportunity to interview Chris recently and the discussion touched on his first encounter with Partick Moore, tips for budding astronomers, the nature of dark matter, and how ordinary people can find the next Voorwerp.
All the good bits have been transcribed for you below. Enjoy!
NSB : To start with I just wanted to take you back to when you were 19 and you won an award for an article on dust around stellar objects.
Chris Lintott : That was a long time ago, a summer project that I carried out at the University of Hertfordshire, but I had been interested in astronomy as a kid, with binoculars and then with a very small telescope. I was blown away then as I am now by the idea that we are on a small planet looking up at the immense vastness of the night sky and yet we can do something to understand our place in the universe. And that is the idea that inspired me to become an astronomer, that’s what been driving me ever since.
NSB : Were there any other influences, a book perhaps? Or a relative who was interested in astronomy?
Chris Linott : If it was anyone, it was encountering my Sky at Night co-presenter Patrick Moore, who everyone knows and associates with astronomy. He gave a lecture at my school when I was about 12 about the outer planets. I don’t remember anything he said about the outer planets but I remember him saying that if he came back in 10 years time the lecture would be completely different because we didn’t know everything. And it was the first time I’d heard an adult say that we don’t know everything yet and that there is still exploration to be done. And that’s the inspiring idea I think.
The Dark Spot on Uranus.A feature that was yet to be
discovered when Patrick Moore visited Chris’s school.
NSB : And then you went on to read, perhaps a little surprisingly, Natural Sciences (see also here) at Cambridge University. What was that like and why did you pick that subject?
Chris Lintott : Natural Science at Cambridge is an overall course, it’s a bit broader than most other universities so I did physics, chemistry, some geology - including tramping over Scottish Islands, which was great fun - and eventually specialized in theoretical physics but always with the aim of applying that knowledge to astronomy. In fact my first real research job was in the chemistry of star formation and I used a little bit of that Natural Sciences to try and understand how stars are born and what influences what kind of star you get.
NSB : What was the pace of the course like, was it the case that if you missed a lecture you could not get back up to speed or was it an easier pace?
Chris Lintott : It was busy, Cambridge and Oxford where I am now a researcher have a model of eight week terms, so it is very intense for those two months, the number of times I complained about 9am Saturday lectures was immense, but the point of doing that is to really immerse people in the subject and give them a sense of the scope of what is going on. People learn in different ways but, at least for me, it was very exciting to be thinking all day, every day about the exciting problems of physics and science. But it was pretty pacy!
Trinity College Great Court. A building that took a lot of chiselling to build.
The Centre for Mathematical Sciences (which required very little chiselling to build)
is a low energy building comprising a grass covered central hall, natural ventilation and night cooling.
NSB : For any kids out there who are thinking of following a career in astronomy, perhaps going to University, what tips would you give them for subjects to study at A-Level and what extra-curricular activities would help them.
Chris Lintott : There are a couple of things. First of all, astronomy can be a wonderful hobby, so if you are interested in looking at the night sky then you should contact your local astronomical society, they are a very good source. If you are more interested in doing it seriously, if you are doing A-Levels then cover the sciences, particularly maths and physics but then lots of university departments, including Nottingham, do all sorts of public outreach and have all sorts of work experience opportunities as well - I ended up doing the work on star formation that you mentioned by winning a bursary to spend some time at the University of Hertfordshire and just getting a taste for research. When I grew up you had to do that through schemes, I applied to universities for a placement. These days the projects I run online - things like www.GalaxyZoo.org or the www.PlanetHunters.org at www.Zooniverse.org give everyone the chance to do some research from their own computer and so for those who do not have the luxury of being able to get to a big university they are probably a good way in. Sitting in front of you computer you have the same access, in most cases, to the data as I have as a professional astronomer and there are certainly places where you can take the time and beat us to discoveries. So I think it’s a very good time to be a kid because you can play the professional game, it’s not just sitting in front of the TV watching, you get to actually take part, long before you get near a university.
Amateur astronomers watching the night sky. . .
. . . from somewhere warm by the look of them
NSB: We often see animations on the TV about how stars form, but it is never clear to me what happens in that first moment when a star starts to shine. Can you paint a bit of a picture for us?
Chris Lintott : Stars form in nebulae, which are big clouds of gas that are, crucially, full of dust. Not the dust that you sweep of your mantelpiece, that’s something else. Think sand grains, think grains of silicon and carbon about a tenth of the size of a sand grain. What happens is that the dust is able to block out the light from all the other stars in the galaxy so inside those clouds it’s very, very cold, about -270C. These are some of the coldest places in the universe and when you cool gas down to that low temperature all the molecules slow down and they are attracted by each others gravity and so, over a period of about a million years the cloud will compress into, we think, something like a sphere. There are no planets at this point, think of it as a blob of gas within a larger gas cloud, it gets denser and denser and there will be a point, right at the centre where the density is so high that the atoms start colliding with each other in nuclear fusion reactions and release a little bit of energy and that’s the birth of the star. Once that starts to happen the star blows off its surroundings and emerges from its cocoon, emerges from its dust cloud. This leaves behind a disc of material around the star and the planets form later from the left over material in this disc.
The fascinating part of star formation is that it sounds reasonably straightforward but the details are still incredibly obscure so things like why stars are the size they are or if you want me to point to one of these clouds and tell you whether it is going to make a Sun sized star or a much bigger one - the truth is we don’t really know and so there is all this messy wonderful detail that we have spent a lot of time trying to understand.
NSB: So how long does it take to “light up”. Is it a few seconds, a few days?
Chris Lintott: First of all, don’t think of it as an explosion because that suggests that it is a one-off event, a “bang” and then the star is formed. What happens is that the molecules start colliding with each other, it happens gently at first and then the pace picks up. It takes about ten thousand to a hundred thousand years in total for the star to go from cold to the stable big ball of gas with a hot core that we are used to thinking of as a star. Actually, that slow heating up can have quite a profound effect on the surrounding material which is cold and icy and you see the ice that surrounds the dust (particles) can suddenly evaporate and you suddenly see all this material appear as gas around the young star- and that is one of the things that we look for so that we know that this star has just switched on. And during this process the star will still be contracting so the density will still be going up.
You know, being a star isn’t quite as clear cut a thing as you think. Jupiter is about a thousandth of the size of the sun and it is only just a failed star, it wouldn’t have had to get much bigger before it had started to have these (nuclear) reactions and so there is this blurred line between very big planets and very small stars that we are still investigating.
(NB: See here for more info on the "brown" area between planets and stars)
“being a star isn’t quite as clear cut a thing as you think”
NSB: There is a lot is stuff in the news at the moment about extra-solar planets, planets around other stars. But this is relatively recent field of study, isn’t it?
Chris Lintott : Yes, planets around other stars were only discovered in the mid 1990’s and, sitting here today, we know of about 800 that we have confirmed and probably another 3,000 good candidates. What’s amazing about these is that we find them everywhere - most stars in our galaxy have planets and as there are a hundred billion stars in the galaxy that adds up to quite a lot of planets. But also, our solar system is beginning to look a little unusual - we are used to having small planets such as Mercury, Venus, Earth and Mars near to the Sun and then bigger planets, Jupiter, Saturn, Uranus Neptune, further out. And we used to think that was a fundamental rule, that was just how the universe was, but it turns out you can have almost any mixture of planets. We see big planets close to their stars, we see big planets mixed up with small planets and we see really quite chaotic processes. That’s interesting, anything that makes us unusual is interesting, it must be telling us something profound about why we came to find out selves on this solar system, why life evolved on earth whereas it hasn’t seemed to around the rest of these stars, at least not as far as we know.
NSB : One thing I read is that some of these extra-solar planets are going around their stars in just a few days, and I can’t quite get my head around how they can do that. How can that happen?
Chris Linott : We have found a whole category of planets that we call “Hot Jupiters” that are the size of Jupiter, the biggest planet in our solar system and are zipping round maybe 10 million miles from their star. The question isn’t really how can that happen, because the orbits are quite stable, although they make the planet a really unpleasant place. The question is ‘how did they get there?’. Because we don’t think there was any way to form such a big planet so near its star, so we have this idea that as the planets are forming in the disc of material that is left over around the star, a lot of the time the big planets migrate inwards due to a kind of friction and they slowly spiral inwards and stop at the inner edge of the disc which can be very close to the star. So that is the kind of thing we think is going on, but we only started to discover these planets some 10-15 years ago so we are still struggling to quite piece together what’s going on.
NSB : A planet called Kepler 22b has been in the news a lot recently. Can you tell us a little bit about why this is so exciting?
Chris Lintott : Well, the first thing that is exciting is that it is Kepler planet. Kepler is a space telescope launched by NASA that stares at about 150,000 stars and every 29.4 seconds it measures their brightness and then we look at the variations in the brightness and are looking for a ‘wink’ that occurs when a planet gets in front of the star. (Secondly) Kepler22b is in what we call the ‘habitable zone’ of the star. All planets are great, I don’t want to favour one set of planets over another, except that we would really like to find a planet like the earth. What do we mean by ‘like the earth’ - well, one thing that is important for life is the ability to have liquid water on the surface. There are good reasons to believe that liquid water is necessary, at least for our kind of life. And so there is a range around any star - I like to call it the ‘Goldilocks Zone’ - where it is not too hot and it’s not too cold and liquid water can exist. In our solar system, Venus is way too hot, Mars is slightly too cold and the Earth is right in the middle of the zone.
Kepler22b was the first small, rocky planet that was found in the Goldilocks zone around a sun-like star. So it is the closest that we have got to an equivalent to our Earth. But sometime this year I am almost certain that we will find an earth like planet going around a Sun-like star with the right temperarure for liquid water to exist. So we probably not far off from being able to to point to a star in the sky and say that there may well be a clone of the earth going around that star. And that is pretty stunning.
Kepler 22b, located in the Goldilocks Zone of a star 600 light years away (!)
NSB: We have a question from a caller who is asking, quite sensibly, how can an ordinary person see the stars better? What kind of small cheap kit, I think he’s asking, can people use?
Chris Lintott : The (local) astronomical society is definitely the key because you can borrow other peoples kit. If you can’t do that or you want something of your own, the standard advice for years is still true and that is to go out and buy yourself a decent pair of binoculars. You can get great binoculars second hand and that will enable you to explore the sky. Will be able to see the colours of the stars, pick up some of the star clusters and have a good view of the moons of Jupiter, and of course our own moon as well. So that is the gateway I think, start with that and then you can get excellent small telescopes for a couple of hundred pounds. That’s a lot of money to some people but it’s a lot cheaper than it used to be. The key thing to look for is the size of the lens or the size of the mirror. For a telescope with a lens you want at least a three inch lens, for a telescope with a mirror you want at least a 6 inch mirror. At home I have a little six inch mirror telescope, a reflecting telescope, and I enjoy that immensely and that keeps me happy. So you don’t need to go too far to be able to get a really nice view of things like Jupiter and Saturn and the Orion nebula which is a star forming place like we have been talking about.
NSB: I’ve tried to use some cheap binoculars and the view was a little shaky, do you think a tripod would help?
Chris Linott : Yes, decent binoculars plus a tripod will go a long way because then you don’t have to lock your arms in and you can really concentrate on looking. One nice trick, by the way, is that you will always see faint things better out of the corner of your eye. So if you are watching the sky, pay attention to what is around the edge of your view. It’s to do with the way the eye is designed. Also, if you are looking at something like Jupiter, it is often a good idea to try and sketch it because this makes you pay attention to the finer detail.
Jonny and Ralf had the right kit, but still needed to realise
that starwatching was best carried out at night. . . .
NSB : We keep hearing about ‘Dark Matter’ and that this is what a large proportion of the Universe is made of. Can you explain what this stuff is? Can you hold it in your hands?
Chris Linott : This is the slightly embarrassing fact that we don’t know what most of the Universe is made of, which seems like quite a basic question. Yet we see the effect of it and we blame it on dark matter. When you hear the term ‘dark’ by the way, don’t take it too seriously, it’s just that astronomers don’t understand it so they call it dark matter.
We know that it’s there because of things like when you look at a galaxy like the Milky Way, you can work out how fast it is rotating and if you didn’t have dark matter it would fly apart. Yet the galaxy stays there so it must be held together by extra gravity. And so we think dark matter is probably a set of heavy particles, with maybe each particle weighing as much as a whole Copper atom, but they have to be neutral because they don’t interact with light, they don’t give off light and they don’t really interact with normal matter either.
If we are right about the amount of dark matter in the universe, if you hold out your hand, tens of thousands of dark matter particles are passing through your hand every second. They are going through your hand, through the earth and out the other side without interacting with any of those atoms, which is why it is so hard to detect. But this is what the universe is made of and all the other stuff, the Hydrogen the Helium, the Carbon and all the rest of it, is almost just a sprinkling on the top.
About a sixth of the matter in the universe is made up of normal stuff and the rest is this dark matter. But it’s just particles and we are hoping that the particle physicists will find some for us. There are good reasons for believing that their mass is around that of a Copper atom and if it is, they may find them with the Large Hadron Collider.
People have looked and thought that maybe neutrinos, which are these fast moving particles that are passing through you all the time and only vaguely interact with matter, are the dark matter and it turns out that if you had a universe filled with neutrinos, you wouldn’t form enough galaxies because neutrinos move around very fast and are not very good at building big bulky structures like galaxies. So we can actually rule that out, only about less than a percent of the universe is made up of neutrinos.
NSB: You wonder whether there is a dark matter universe where they are wondering where 10% of the universe is. .
Chris Lintott: It’s interesting, because dark matter can have its own physics, so these particles might interact with each other in all sorts of ways that we don’t understand. There are unlikely to be dark matter astronomers though, because we know that dark matter doesn’t clump together so you can’t have a dark matter planet. We’ve looked for them and haven’t found them. So sadly, no dark matter radio shows, no dark matter astronomers debating where the other 10% are. But it’s a fun thought.
NSB : That must have been an interesting project meeting ‘Let’s look for dark matter planets”.
Chris Lintott : This was a huge thing, because maybe if you don’t like the idea of these particles floating around, maybe, for example, dark matter is just loads of Jupiter sized planets floating through the galaxy. But there were experiments that definitively ruled that out.
Tens of thousands of dark matter particles
could be passing through this hand every second. . .
NSB : Perhaps we can now move of to some of the ‘Citizens Science’ projects that you are running. Let’s start with the Planet Hunters project because that links in to a lot of the things we have been talking about. Can you give an outline of what this project is all about?
Chris Lintott: I’ve already mentioned this Kepler spacecraft that is looking at all these stars and looking for ‘blinks’ when planets get in the way of their parent star and most of the time computers can find these things but we know that there are some that escape because the star is doing other things or because it is complicated. So if you go to www.planethunters.org on the web you can see this data and the site will teach you how to spot if there is a planet and we are actually having great success in rescuing planets that the professionals have missed and that the computers have missed and that individuals sitting in front of their browser have managed to rescue. You don’t need a degree in physics to be able to attack this as it’s just a pattern recognition test and that is something that humans are good at. So we have gone from the first planet being discovered in 1999 to it now being possible to discover a planet from the comfort of your own home, to find something that no one else knows is there. So these kinds of projects, which we are seeing popping up all over science and all over astronomy are very exciting for that reason, they give the control back to the general public instead of professionals like me and allows people to make their own discoveries. This isn’t outreach, this isn’t a fun thing, we actually need peoples help - there aren’t enough astronomers in the world to look at all this data, so without the help of the general public planets will go unfound - which is quite a profound thought.
What’s nice about this project is that if these are some planets that the computer has missed, they are likely to be unusual in some way so we might find the really exotic interesting ones by carefully carrying out this test
Find a dip in luminosity like this and you might have found a planet!
NSB: Another fascinating project that you have running is called Galaxy Zoo. Can you explain what this is?
Chris Lintott : Galaxy Zoo is a very similar problem, we had images of over a million galaxies and if you want to understand a galaxy, which can be made up of 100 billion stars, you want to look at its shape because its shape tells you about its history. It tells you whether it has collided with other galaxies, whether it has done something on its own, whether there has been star formation and so on. But you are looking at a shape in a fuzzy image and that is something that computers are pretty poor at but humans are very good at. So if you go to Galaxy Zoo you will see an image of a galaxy that no one else has seen, because it was taken by a robotic camera, and then we ask you a few questions about it. We ask you can you see a spiral arm, does it have a bulge in its centre, if there are spiral arms, how many are there. And each of these questions can help us out with understanding how galaxies evolve. And again we need as many people as possible to take part. It takes a couple of minutes, if that, to get started. I know we have six year olds doing GalaxyZoo, I know we have eighty year olds doing GalaxyZoo and it just takes a few minutes to help scientists really understand the evolution of our universe.
NSB : Can you tell us what the “Voorwerp” is?
Chris Linott : Oh yes! Voorwerp means ‘object’ or ‘thingy’ in Dutch and this was a giant blob of gas discovered by Hanny van Arkel, a dutch schoolteacher who was on Galaxy Zoo and it is gas cloud that has been heated up by interactions with a neighbouring galaxy. It’s a fascinating object and we have been able to chase it up with the Hubble Space telescope, we’ve pointed pretty much every telescope around the world that we can get our hands on at this beautiful object. Why it matters for GalaxyZoo is that it is obviously weird and interesting when you see it, but it is that human ability to point at something and say ‘that’s odd, that’s not a normal galaxy’ which computers just don’t have. So without humans going through the images, we miss these beautiful discoveries.
NSB: And I think that is what happened in this case, she found this object and asked “I’ve found this, what’s that strange thing underneath?’
Chris Lintott : That’s right, and we looked at it and said ‘well, we’re not sure either’ We got to do what I used to think astronomers did way back when which was to find a weird object, point many telescopes at it and then argue about it. And that’s fantastic.
Engage with GalaxyZoo and maybe you could find a Voorwerp
(it’s the blue/green thing below the galaxy)
NSB: One last endeavour, before we come to the end of the interview, can you tell us about the Milky Way Project?
Chris Lintott : At the beginning of the interview I made star formation sound very straightforward but finding those places where stars are forming is really difficult and one thing we can do is to cheat by knowing that when stars are new they are quite violent and they blow bubbles out of the gas around them and you can go looking for these bubbles in images - it’s another pattern recognition test. And so by flicking through beautiful images of gas clouds in our galaxy drawing bubbles, people at the www.milkywayproject.org have created a catalogue of star forming sites in the Milky Way. The kind of thing we are looking for here is whether star formation triggers other star formation. This has been argued about for years but we have only now got enough data to be able to attack this problem. From my own point of view, whilst I don’t have a favourite project, the images in the Milky Way Project are so beautiful, our galaxy is such a glorious place. So this is certainly the one that I relax with when it’s cloudy.
NSB : One thing that I was very surprised to hear in another lecture I heard at Nottingham University was that in these very beautiful images, the colours are not what you would actually see but are instead where an astronomer has picked, say, red to represent Hydrogen, green to represent Oxygen and so on.
Chris Lintott : Yes, in the case of the MilkyWay Project we are looking in the Infra-red, beyond what the human eye can see. So although the colours mean something they are not what you would see if you were floating in space, and that is true of a lot of astronomical images.
The MilkyWay Project allows you to highlight
places where stars may be forming.
NSB: Is there anything else you would like to say, any message you would like to get out to the general public?
Chris Lintott : I think we have already covered it - If you go to www.zooniverse.org, pick a project and dive in - you will genuinely be making a difference to what scientists want to do - and we need your help. We can see where people are coming from so we’ll be expecting a huge spike from your area.
NSB: Ok, so here’s an opportunity to put Nottingham on the map. Now lastly, let’s move on to out last question, the ‘special question’ that we ask of all out guests, which is simply ‘ What do you think is the best thing about living in the UK?’
Chris Lintott : I’m standing near New York, in out collaborators office so right now I could kill for a cup of tea! But more seriously, I think that the UK is still a place where ideas are taken seriously, where people are interested in the fact that we can discover planets around other stars and that people are willing to spend their spare time doing that. So that mass collaboration, that mass interest in some quite serious ideas is, I think, a huge strength.
NSB: I wouldn’t want you to name places, but have you been elsewhere in the world and not felt that?
Chriss Linott : Yes, weirdly, I think in the UK we are often portrayed as quite cynical, but actually, we know from the work we have done with the BBC, that there is a huge interest and desire to be part of understanding the universe and that is something that, whilst not uniquely British, we have managed to retain despite the crises of the last few years and the cynicism about money and politics and so on.
NSB : Well, thank you so much for taking the time out from your schedule to call us from the US, it has been absolutely brilliant !
Chris Lintott : My pleasure.
Chris was interviewed on the Buidling for the Future show (Wednesdays at 5.15pm ish) on Radio Dawn 107.6FM, one of Nottinghams community radio stations.
Astronomy links at Notts Astronomical Society
Society for Popular Astronomy
Image Sources :
Dark Spot, Trinity College, Mathematical Sciences, Amateur Asstronomy, Small Stars, Kepler22B, Binoculars, Hand(NSB own), Luminosity, Voorwerp, MilkyWay