Anyway, they recently had a mark making/graffiti related exhibit & it was a really fun piece, especially as it was so interactive. Check it out below:
http://lightgraffiti.littlesun.com
You pop into a room, wave a solar flower at a screen, to make your mark and hey presto the sun is (re)born. They give you a code too, so you can check out the image you made when you get back home. It's a really accessible exhibit and a lot of fun, though the room itself is tucked away and the assistant I asked told me I had to buy a flower first, then wait for a light show (you don't need to but I think this was more about a show later on in the day related to the solar flowers). You can buy them, at £16.50 I believe, and they're solar torches and v cute, I don't now how powerful they are in real life.
Here's a few Little sun : sunlight graffiti images:
Os Gemeos and friends on the outside