27/30 Heather Couper looks at research that shows stars are like controlled nuclear explosions.
26/30 Heather Couper looks at William Herschel's discovery of infrared radiation 200 years ago.
25/30 Heather Couper looks at arguments over the laws of physics and the universe's creation.
24/30 What we can see is only a fraction of matter in the cosmos. Heather looks at dark matter.
23/30 Heather Couper looks at the discovery of quasars, huge black holes a long way from Earth.
22/30 Heather Couper considers how the concept of black holes gained credence in astronomy.
21/30 The discovery of radio waves in space, and how it led to the discovery of the pulsar.
20/30 The Big Bang theory of how the universe began, and what its opponents think.
19/30 How did the discovery that the universe is expanding impact upon Einstein's theories?
18/30 Heather Couper traces our understanding of nebulae, island universes outside our galaxy.