That stuff pictured above is aerogel, aka "solid smoke", which was used on NASA's Stardust probe to capture dust from comet Wild 2 and return it to Earth—along with a handful of precious samples of interstellar dust, giving a rare glimpse of material from outside our Solar System.

In this show, Stu also talks to British scientist Maggie Aderin-Pocock, host of the long-running astronomy TV show The Sky at Night, and who's also known for answering important questions like, do we really need the Moon?