Why Kepler's Somnium is (or isn't) hard SF, and other more interesting questions

Last month BBC producer Louise Yeoman invited me to the Royal Observatory, Edinburgh to contribute to a 20-minute BBC radio programme about Kepler's Somnium, which also featured Andrew Brown, the observatory's Professor Avery Meiksin, and science historian James Connor.

You can now hear it on the BBC iPlayer, and it's worth a listen. Prof Meiksin is a joy to listen to. As for me, well ... I sound a lot more coherent and fluent than I sounded to myself at the time. (Good editing, probably.) Wha...