Dr Lucie Green
Lucie Green is a space scientist based at the Mullard Space Science Laboratory. Her particular area of interest is the magnetic fields within our sun’s atmosphere. She is also a Royal Society University Research Fellow and is a board member of the European Solar Physics Division. Lucie can regularly be seen and heard on TV and radio in such programmes as ‘Horizon,’ ‘Stargazing Live’ and ‘The Sky at Night’.
I think actually being a scientist is about being someone who doesn’t stop playing.
On becoming interested in science
I think I was often bored as a child and when I was looking for things to do I looked around me, so I looked to play with things. I think actually being a scientist is about being someone who doesn’t stop playing, who doesn’t stop wanting to look around them, touch the objects, interact with them and find out what will happen if I do this. That’s the essence of play. I want to do this, I want to find out what happens next. And so when I was a child I looked around me and I was really into wildlife. I used to like counting the numbers of butterflies that would get on the buddleia, or I made a bird hide because I bought a Bill Oddie book and I wanted to know what birds I’d get in the garden. So, it’s just the curiosity. I wanted to know what was happening in the world around me.
On being a space scientist
Being a space scientist means looking up and trying to explain what you see. Looking at stars, looking at galaxies, looking at things more close by, the planets, but for me it’s looking at the sun and trying to understand what kind of object the sun is and why it does what it does. It’s a very active object.
It’s a hard question to try and answer what drew me to exactly to the sun because it was a series of steps of following my nose and just being interested in what I see around me. And first of all it was about using the Universe as a physics laboratory. So I got into astrophysics, then I went to an observatory in the Crimea of all places and somebody, a female scientist, showed me the sun through her telescope and that was my Eureka moment of moving from other stars to looking at our local star and actually from then on, I was totally hooked.
At the moment I’m working on so many things but they all come down to understanding why the sun is active. So, the yellow disc we see in the day time sky hides the fact that in other wavelengths of light, not visible light, for example ultraviolet light and in x-rays, we see a really dynamic sun. A sun that has explosions and eruptions happening in its atmosphere and everything I do is based around understanding why and how those things happen. So one day I might be studying huge eruptions called coronal mass ejections, another day I might be studying sunquakes which get triggered inside the sun when these huge eruptions happen. But the most exciting thing that I’m working on at the moment is something called Solar Orbiter and this is a space craft that we’re going to launch in 2017 and it’s a kind of Icarus style mission. We’re going to launch it and it’s going to be put into an orbit that gets very, very close to the sun. So it takes three years to get to the right orbit but when it does, it’ll be closer to the sun than the planet Mercury. And from that viewpoint we’ll be able to answer things like ‘Why do these eruptions occur?’
On the importance of understanding the sun
It’s important for us to know about the sun because it is our standard star. We’re seeing a star, at one snapshot in time, in a huge amount of detail. We can see the surface, we can see the atmosphere, we can see the activity. We can even see inside the sun using sound waves which resonate around inside this spherical cavity and make the surface oscillate, so in fact we’re seeing a star from the inside out. And we can use that to build up a detailed picture of how our sun is working and then use that knowledge and apply it to other stars. But also the techniques we use to study the sun. So the very essence of using sunlight, and then breaking that apart to its component colours to tell us things like how hot the sun is, what it’s made of; those techniques were developed to study the sun and then applied to all the other stars that we can see.
And then the final reason, for me, on why the sun is so important to study is because it has such a major effect on us. In particular there’s an area called space weather which is how the sun, through its emissions, creates a changing space environment local to the Earth which ultimately causes problems with our electricity networks, our satellites, our communications, so space weather is the latest kind of weather prediction that scientists are interested in.
The great thing about the sun is that anybody can access all of the data. Any of the data that they want to get their hands on. There’s always been a policy of open access, so any images that are captured through NASA satellites, say for example the Solar Dynamics Observatory, you can go online and get them yourselves. We’re happy for anyone to access the data. What I love is, because the sun combines the beauty and the science – it’s got the aesthetics and the details of the physics – because of that it attracts so much attention and there are so many images and pieces of information available on the internet or equally people can come and listen to people like me talk, or my colleagues.
On the future studies of the sun
So a discovery that I would like to see happen in my lifetime relates to what’s happening inside the sun. The sun is a magnetic star and it has a magnetic cycle. Every eleven years the whole magnetic field of the sun flips. So at the poles, the north and south poles of the sun, you have the concentration of magnetic field, so just like with the Earth, but whereas on the Earth it takes thousands or hundreds of thousands of years for the poles to flip, on the sun it happens every eleven years. Flip, flop, flip, flop. And something inside the sun is driving that. We have some sort of idea but it’s more a cartoon of what’s happening and I would love to see enough data be collected to confirm that cartoon or to tell us that we actually have to start again, so it’s called the solar dynamo, what’s generating and evolving the magnetic field.
On the Aurora
The Aurora are a visible manifestation of the connection between the sun and the Earth and they’re the most beautiful manifestation of that connection. So it starts with the fact that the sun has a very hot atmosphere, a million degree atmosphere which is so hot that it’s expanding out into the Solar System. The gravitational pull of the sun can’t contain it and it expands out for millions and millions of kilometres. So it rushes over the Earth, in fact it rushes over all the planets in the Solar System. And the Earth with its magnetic field is constantly immersed in this flow and it squashes our magnetic field, it draws out our magnetic field, we’re basically a wind sock in this solar wind and sometimes the solar wind can break a hole in our magnetic shield and during those times you start to have energy put into our magnetic field and that’s at the heart of how the Aurora are produced. And it becomes a little bit sort of technical in that the solar wind is able to open up the Earth’s magnetic field and sort of peel the magnetic field lines back. So you’ve got the sun over here and the Earth over here. The solar wind rushes in, peels back the Earth’s magnetic field and places it on the night side of the Earth. So in fact a long tail of magnetic field builds up and when that’s built up, well, I don’t know, to a certain point, to breaking point, suddenly the magnetic field sort of collapses and it’s almost like you’ve pulled out an elastic band and then suddenly let go of it and it contracts back towards the Earth. And when that magnetic field rushes back towards the Earth it sends highly, or very fast moving particles down the field lines and they crash down into the top of the Earth’s atmosphere, and when that happens they give up their energy, into the gases, into the atmospheric gases and those atmospheric gases give up their energy by glowing. And that’s when you see the oxygen and the nitrogen giving off red, blue, green, purple lights that form the Aurora. So it’s the energy that ultimately came from the sun in the solar wind, reconfigured our own magnetic field and then sent particles crashing down on top of our atmosphere. Straight forward! This is why no-one ever understands how the Aurora are formed!
On science education
It was very natural for me to get involved with education, so I’m interested in both going out and giving talks about science, so maybe for school children or an adult education audience, but I’m also interested in education policy as well and how science should be communicated: what the benefits are, what role it plays in the classroom. And for me it’s very natural because I never lost my natural curiosity, so it seems completely second nature to me to go out and talk to a range of people about science. I don’t see why scientific discussion should stop where my physical building stops. And also, when you go outside your laboratory and speak to people who are just members of the public that’s when you can really find that passion and interest. For my colleagues it’s very day to day but going out and speaking to a school child about what the sun does and showing them the images that turned me onto science, that’s such a great feeling. You know, when I see someone look at the sun with the same sense of wonder as I have I find that very rewarding and that’s the essence of it. It’s about sharing with other people the science that is all around us that is ultimately inspiring.