Dr Chris van Tulleken, Dr Hannah Fry and Michael Mosley examine the latest research and explore some of the big questions about Covid-19 and the pandemic it has created. Michael visits the UK government's high-security laboratory Porton Down, where vaccines are being tested. He also uncovers what the experience of the 2002 SARs epidemic reveals about this one. Both were caused by coronaviruses, but certain key changes to today's virus have allowed it to infect the world, where SARs was contained.

The Sun is a endless churning cauldron of nuclear reactions and our planet is at its mercy. Revealing its inner workings was once mission impossible, but not any more. We've recruited a fleet of spacecraft that monitor the Sun 24 hours a day, under close surveillance. We just might have what it takes to defend our planet.

The cosmos, with its billions of galaxies and countless stars, isn't the only one. We share our lives with another universe: The world of the small, of the viruses, of the bacteria. We call this strange hidden kingdom the Microcosmos. We share our world with the microcosmos. Will we coexist in an uneasy peace, or will it destroy us?
In 2020, A tiny virus caused a global pandemic, COVID-19. This pandemic makes people see the world completely differently, because there was an invisible universe, pretty much ignored for the most part. Very, very tiny things have a huge impact on our lives. The microcosmos is complex, while some parts kill us, others keep us alive. The microcosmos is responsible for the very oxygen that we breathe and the soil on which we live. And it will influence our future as we venture out into space.