 Hello again. Do you want to learn about supernova remnants? Oh yes. That's to do with big stars exploding, right? Yes. So the star stuff that's exploding outwards is what we call the supernova remnants. These shock fronts give off all sorts of light. So we can take pictures of the supernova remnant in all the different colours of light, like in the light that you and me can see, and in X-ray light, and CTA will be looking at gamma ray light. Supernova remnants are very important for many reasons. If it weren't for supernovas, the Earth wouldn't be here. You and me wouldn't be here either. What? Supernovas are very violent explosions that give out huge amounts of energy, which means the star stuff blasted out can join together to form heavy metals like lead that you find in weights, and uranium used in nuclear power plants. These can only exist because of supernovas. Another important thing about supernova remnants is that the big blast from the explosion accelerates charged particles to really high speeds, much higher speeds than any particle accelerator made by people can reach. Not even the fastest man-made particle accelerator, the Large Hadron Collider at CERN, can make particles move that fast. We call these accelerated particles cosmic rays. Oh, so cosmic rays aren't really like rays. No, they're just really fast particles. These cosmic rays bombard the Earth, and we think that these supernova remnants could be where most of these cosmic rays come from. These cosmic rays are interesting because they play a role in the making of stars, but actually we still aren't totally sure about where they come from and what it is that they do in space. There is still a lot to learn about supernova remnants and cosmic rays and the effect they have on the space around them. CTA aims to look at them in greater detail through gamma rays and find out about the particle acceleration that goes on and its effect on the space around. Use to find lots of stuff out. Thanks, I'll try.