Shown just a day after it goes out in the Us, American Idol should offer a slicker, glossier X Factor substitute for those currently in Cowell withdrawal. It's also the first series without original judge Paula Abdul, as the well-known vocal expert Ellen DeGeneres takes her place on the panel. The expectation is that she'll be the fluffy, kind one, but, amid rumours that the Cowell himself might be leaving soon, imagine if she's been brought in as a replacement evil dream-crusher with a knack for scathing put-downs. Now that would shake things up a bit.
Horizon: Why Do Viruses Kill?
Tonight's Horizon explores the weird and often terrifying existence of viruses – some of the smallest, and deadliest, organisms on the planet. What makes one a killer and others benign?