Why are we going gaga over Gaia?

Astrophysicist Duncan Forgan describes it as the most exciting mission since Hubble; so what is it that sets Gaia apart from all the other probes?
25 October 2016

Interview with 

Duncan Forgan, University of St Andrews


Astrophysicist Duncan Forgan describes it as the most exciting mission since VST Snaps Gaia en Route to a Billion StarsHubble, so what is it that sets it apart from all the other probes? He explained to Graihagh Jackson...

Duncan - It's nice to capture people from all different kinds of the field, and we're all talking about it. All you have to do is look at Twitter and the Gaia DR1 hashtag and it's just abuzz with people downloading data, doing some science, getting some figures and plots, and saying look what I've found.  And that's just within like a day - as we speak it was released yesterday.

Graihagh - Scientists like Duncan Forgan have big plans for Gaia's data and it goes beyond the mapping the milky way.

Duncan - So we're really in the stage where this is just coming in so quickly and papers are starting to appear on the web even today with like the first analysis of this data. So this is what Gaia has done very well in the sense that making sure it's data works with everybody.

Graihagh - And is all this data that's coming back - you're talking about people downloading it and writing papers - is it all open access then?

Duncan - Very much so. So if you have the knowhow and you understand how to manipulate the data set then yes, you can download it yourself and you can look at what they've produced. It's an incredible achievement that it's gone open source so quickly and the science that's coming out is going to be absolutely astonishing.

Graihagh - Just returning to the data stuff, you talked about this is the first data release - how much more is there to come then?

Duncan - Well this is the first year of data that's been collected by Gaia and Gaia has a five year mission. So you can expect, well it depends exactly how they're going to parcel up the releases, but you can expect at least five releases. There might well be more because, as time goes on, Gaia's not just going to measure everything once, there's going to be a small sect of objects - well I say small, there's still millions of objects - where they measure them lots and lots of times.

And this is where lots of cool science comes in like the motions of the stars, and it's also going to tell us about the motions of the asteroids in the solar system. It will help us detect exoplanets by watching for dips in the star's light and that will tell us if planets are actually passing between us and the star. It will even be looking at how the star wobbles in the sky and that wobbling will tell us if there's a planet tugging at it with it's gravity.

This has never been done before - what they call astrometric detection of exoplanets. No-one has ever managed to do it but Gaia will probably be the first to do it. So there's a big laundry list of all these things that Gaia can do that nothing else can, which is an amazing achievement for a single instrument.

Graihagh - Yeah, I can tell. I can hear that you're really excited about it all but I wonders what's this really mean in the grand scale of things? I mean, I'm just thinking the mission is touting as finding out where we came from and some of the fundamental questions of physics. But I mean really, is that really going to occur? I feel like there's lots more work and lots more known unknowns as well as unknown unknowns if you like.

Duncan - Well, I think this is the thing with any kind of big mission where you make big claims. You kind of hit it on the head there when you talked about known unknowns and unknown unknowns. So we have a good grasp, obviously, on the known unknowns because we have the laws of physics and we can construct models to say these things can possibly exist but we haven't seen them yet. But the unknown unknowns is really where a lot of the fun is because that tells you where your laws of physics are maybe incomplete, or incorrect, or they need some kind of revision, and that's where it gets really fun.

So I think what Gaia are really kind of selling and I think astronomers agree, even though I'm not technically part of Gaia, I would certainly say this makes sense. What Gaia is doing is it's telling us about the fundamental structure of our galaxy. So where the stars are tells us something about where the mass is in our galaxy. It may even start to tell us something about the dark matter that exists in our galaxy. It tells us about the stars themselves, it tells us about how far away they are. It gives us better information about their ages, which is really important when you're doing things like studying where stars formed and why. It tells us more about the planetary systems that we expect to see. And again, knowing the stars better means that we know the planets better because a lot of our planetary information is based on how well we know the stars. So if you know the star poorly, you know the planet poorly and Gaia's going to help us know the stars better which is great.

And then again, understanding the solar system in general and mapping out the contents of the solar system, which again is a big task because Gaia will still find things that we haven't seen yet. And then, of course, there's the things that Gaia will find that we have no idea to expect. And again, going back to Kepler and the bayesian star, no-one predicted that would come along. So the unknown unknowns are also the very exciting part too.

Graihagh - Fab! That was everything on my list really. Is there anything else that you'd like to add?

Duncan - I think the only thing I would like to add is that we're all really excited. I mean the discussions. I wasn't in work yesterday when the data was released but I was tracking it on Twitter. I've come into the office for an hour before speaking to you this morning and the whole place is abuzz and people are frantically trying to do science, and submit paper,s and just generally be excited and enthused by what's happening. So there's a real genuine passion and excitement in the air.


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