When you mix paint, it's a subtractive process. You start with white, and you're putting a layer of something on top of it, which allows a certain wavelength of light through but takes away everything else. So whatever you add, it always gets darker, and changes colour in a certain way. When you mix light, you're starting with black, and you're adding something. If you think a the way a TV works, it sends out red and green and blue and makes a coloured picture. But it's adding something all the time. Paint is always taking something away. It's a fundamentally different way of doing something. An interesting aside to that is that when you take a picture with your camera, it records red, green and blue. When you print it out, the printer has to convert it into something called CMYK, which is cyan, magenta and yellow. These are mixed to make the colours that you see. Printers use a different palette because when you add things subtractively, you end up with different colours. Interestingly, the K is black. In theory, if you mix the cyan, magenta and yellow together, you get black, although in practice you don't quite, so they have to add black to make everything work.

Although the earth might look flat, if you look at it from outer space, it's a big sphere. But it's not straight. It's actually a bit wonky, and the amount of tilt is actually about 23.5 degrees. This means that part of the earth is tilted towards the sun, and part of the earth is tilted away from the sun. On one part of the orbit, the top of the earth is tilted towards the sun, which is the warm summer. This is when you get longer days. Further round in its orbit, it'll be pointed away from the sun. This is our winter, and the days are a lot shorter. Therefore, the length of the day is actually all down to how angled our planet is in space.

A light bulb is an electrical filament. What you have is a long piece of wire, and when you connect this to a socket, it basically completes a circuit. As electricity passes through, the electrical current excites the metal and gets it hot. As you know, an electric fire glows orange because there's electricity moving through it and it creates heat. In a light bulb, it's set up in such a way that it doesn't just glow red, but it glows white. The key thing about a light bulb is that if you have something that is that hot with oxygen around, just like Dave and Derek's brillo pad, it'll burn. So what they do with a light bulb is that they suck out all of the oxygen and put argon in instead. This is what's called a Nobel gas: it's completely unreactive and inert. It helps the filament to stay the right temperature by getting hot and carrying heat away from the filament to the edge of the glass.

Pluto is about 6 billion kilometres away from the sun and light travels at 300 000 kilometres every second. To put that in perspective, if you stood on the equator with a torch and switched it on, in one second the light would travel round the earth at least six times. In other words, it's travelling about a billion kilometres every hour. That means that to get to Pluto, light will take about five and a half to six hours to get from the sun.

I think it's just a myth. Red sky at night, Hackney's burning! It's a well established old proverb, but I'm not sure whether it has any validity scientifically. When you have a very very rich sunset, it's because there's a high quantity of particulate matter (or dust) in the atmosphere. A lot of dust in the air is usually down to volcanoes, traffic, industry and the harvest. But I don't think that it has any linkage to making the weather better. I suppose you could argue that dust might lead to global warming, and that that will warm the planet up, but I don't think the rhyme is all that true to be honest.