The night sky isn't only the pinpricks of starlight we see with our eyes — it's also quietly broadcasting on wavelengths we can't see at all, and for the last century a small community of scientists has been learning to listen. This episode traces radio astronomy from an accidental discovery of cosmic static at a telephone company, through the giant dishes and continent-spanning arrays used to hear it properly, to two of Australia's flagship instruments in the outback of Western Australia and New South Wales.

You'll come away understanding what radio waves are and why they reveal things visible light physically cannot, how Karl Jansky stumbled onto cosmic radio noise while chasing a phone-line problem, how a radio dish and an interferometer actually work, what the 21 centimetre hydrogen line lets astronomers map, what pulsars and fast radio ...