A Ride Around The Universe

Chris touches down in Australia and steps inside a planetarium for the very first time. He talks to Carley Tillet of Horizon about spinning and space junk and makes a quick stop...
05 September 2010

Interview with 

Carley Tillet, Horizon, the Planetarium, SciTech, Perth


Carley -   My name is Carley Tillet.  I work here at Horizon - the Planetarium  - at SciTech in Perth, Western Australia, and every day we get to introduce people to the universe, which is a fantastic job!

Chris -   Now I'm going to make a confession to you Carley.  I've never been in a planetarium!

Carley -   I can't believe that!

Chris -   You're robbing me of my planetarium virginity.  For people who, like me, have never set foot in something like this, can you paint a picture of where we are, what we are seeing and what's in front of us?

Carley -   Okay, so you would have to imagine a really big 18-metre, domed screen.  So rather than a flat television screen, this thing is like half of a sphere and you get to sit underneath it and we project images of the night sky and beyond, up onto this big gigantic screen.

Chris -   So basically for the 150 to 200 seats that are in here, there's a white screen above us that is going to become a surrogate night sky that you can put stars on.

Carley -   Not just a night sky -  we can show the entire universe!

Chris -   Shall we do it?

Carley -   Yeah, I think we should.

Chris -   So how does it work - because this looks like a mission control.  I'm looking at this computer screen and to say "there's a few things to click"  would be an understatement.

Carley -   Yes, there are, lots of things to click and press.  Part of my job is to program the software called DigitalSky by Sky-Skan and I get to input 3D models and show really hardcore astronomical data sets.  But usually, for a planetarium presentation, we start with the simple stuff - a sunset scene -  just so people can get a little bit comfortable before we plunge them into darkness and we can see the Sun setting and the stars in the night sky as they will be tonight in Perth, at about 8 o'clock this evening.

PlanetariumChris -   So, could you recreate the UK sky-scape for me here?

Carley -   Surely could.

Chris -   So you can do pretty much what the night sky would look like from anywhere on Earth?

Carley -   Yes.  Do you want to go to the South Pole?

Chris -   Yes.   I've never been there either.

Carley -   It's a day of discovery.

Chris -   So how is this working?  How does it know what to put where?  Because I can just see millions of little dots of light appearing on what is a surrogate sky above me.

Carley -   Indeed.  Basically, we have six projectors that each project onto a little kind of pie slice of the dome and there are six computers that run each of the six projectors, and then one that controls them all.  And that's the screen that you're seeing right now.  It's the main control computer.

Chris -   It's sort of a lot of computing power, isn't it?  But I guess that's needed.

Carley -   Indeed.  Definitely, especially to achieve the resolution - so the ability to be able to see pictures that aren't pixelated and all horrible.  So we can show a really, really nice image, and people can get a really quite good idea of what's up there in sky.  So this is the South Pole at night time.

Chris -   So how do people react to this when you show them this?  How do they react?

Carley -   It depends on how old they are.  Children tend to be very excited, especially when we do things like spinning.  Adults think it's, you know, quite awesome and inspiring.  Sometimes they don't like the spinning so much, but I think there are many adults that might grumble but we know they enjoy it.

Chris -   Some people say it's quite disorientating because you end up gazing upwards, and because there's no reference point because it's dark, you end up being quite giddy.

Carley -   That's true and - well, it can make people feel giddy.  It's also one of the most amazing points of having especially a tilted dome -  like we have here -  is that people can feel within the scene.  So, at the moment, you're seeing Earth on the dome and I've actually pulled us up into space and if I just rotate around, you can actually feel like you're in space, looking back down on the Earth.

Chris -   Wow!  So how far back from - I should just explain -  so we've now zoomed off of earth's surface, we're out in orbit somewhere -  so how far away from planet Earth?  I can see this giant planet projected in front of me.  How far out are we?

Carley -   About 18,000 kilometres.

Chris -   So that's not quite as far as, say, a satellite that would bounce geostationary images back for TV and stuff, is it?

Carley -   No.  They are about 36.5 thousand kilometres out.  I can actually show you.

Chris -   Oh Gosh!  So now you're projecting all the junk that's orbiting the planet.

Carley -   Yes.  This is space junk, our wonderful trash in the sky.  Which sounds kind of funny at first, but it really isn't especially if you're an astronaut in the International Space Station which we can see here.  It orbits around the Earth about 350 - 370 kilometres above the Earth.  The astronauts on board sometimes have to move up into the Soyuz capsule, just in case a piece of space junk crashes into the International Space Station, which is a little bit scary.

Chris -   But looking at this picture  there are literally thousands of white dots representing debris up in space.  How many objects are there up there, man-made objects in orbit now?

Carley -   There are over 800 working satellites, but as for space junk - it's almost uncountable.  There are so many chunks of space debris -  from old satellites that are no longer working, to paint flakes and nuts and bolts that have fallen off, and even some countries have decided to send missiles towards an old defunct satellite, turning into - what was it - twenty five or twenty-six thousand individual little pieces hurtling around the Earth at more than twenty-six and a half  thousand kilometres per hour.  It's a bit of a mess up there.

Chris -   Are we in a position where people are beginning to say, "Look, we're making a mess as well as at the Earth's surface, also at the Earth's orbit, and we're going to have to clean this up at some point."  Is this actually harming astronomy?

Carley -   Not so much astronomy but certainly it puts a lot of satellites at risk and satellites are not cheap.  We're talking about billion dollar instruments - whether they're for Earth observing or for our cable TV - sorry, satellite TV even!

Chris -   It would be a long cable, wouldn't it?

Carley -   It could be a very long cable.  Yeah, that was a bit of a mistake.  So yeah, there are lots and lots of satellites up there and there is a lot of work going into researching how we might be able to stabilise some of the orbits of some of the older satellites, but also how to basically clean up our act, up there in space.

Chris -   So could you also use this to begin to understand more about the relationships between objects in space, and the Earth, other planets, and so on?

Carley -   Absolutely and even next week, I've been working on a production with an artist called Dave Carson and he's been working with Janos Hennicke who spends about three months per year on Christmas Island, tracking Abbot's Boobys and Frigatebirds, which are birds that travel these massive distances.  So I've been able to visualise data from Janos' tracking, to be able to show that these birds used to travel maybe just one day at a time to catch their fish feed, and now they're having to travel two or three days to get that same feed.  So we can show not just astronomy but of course other science.  I think it really gives people a great perspective when you can actually can look from above at these kinds of things.

Chris -   Ah so you can actually plot information on something like this, relative to the Earth's surface, and use the power of this kind of projection system to - it's like doing a massive google maps mash up, but you've got the world's best projector - isn't it?

Carley -   Pretty much.  Certainly got the best computer screen and what more could you ask for?  Eighteen metres of domed goodness - it's a pretty cool place!

Chris -   So not just for pretty planets.  Carley Tilett, talking to me at the Scitech planetarium in Perth.  And that spinning that she mentioned is actually a vertiginous trick that she's developed to rotate the picture you're seeing, several times a second, which makes you feel rather like a human bowling ball, spiralling through space.  So, do take some anti-sickness pills before inviting her to show it to you. 


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