S1, E3: Helen Czerski investigates the colors invisible to the human eye. To see the universe in a new light, she takes to the skies in a NASA jumbo jet equipped with a 17-tonne infrared telescope. We can't see in ultraviolet, but many animals can. Helen explores what the world looks like to the birds and the bees. With x-rays, we could look inside ourselves in ways previously only possible after death.