when the big bang happened, we only had three chemical elements. hydrogen, helium and lithium. everything else, all of the other chemical elements had to be forged in the nuclear reactions in stars. the carbon that makes up your body, the phosphorus in your dna, the nitrogen in earth's atmosphere, the silicon in the rocks, the silicon in the fibre—optic cables that are bringing the pictures to me here in cambridge, to you in london, all of that chemistry had to be made in those first stars and in their descendants. so it is a really key moment in our story, in the story of the cosmos. it is the formation of all lightness and we want to see it. and james webb is going to show it to us. now it's time for a look at the weather with lousie lear. good evening. it was a pretty miserable start to our weekend. but the weather story did improve as we went through the day.