Where is everyone? We have been listening for messages from outer space for more than half a century, and so far... silence, why? Are we truly alone in the universe? Or is everyone else acting like us and just doing a lot of listening? Maybe we need to be louder. Maybe we need to send more messages out there. But how do you write a letter to an extraterrestrial whose language and culture and biology and mind we have no concept of? And what do you say?
Given all of the unknowns about what they might behave, should we say anything at all?

Exoplanets, strange worlds outside our solar system. We're discovering the cosmos is full of alien planets. Alien worlds that challenge our understanding of planetary systems. Hellishly hot worlds, violently colliding worlds, worlds getting eaten by their stars. There's much, much more out there than we had ever imagined.
Exoplanets are shaking up our understanding of the universe. The cosmos is a chaotic array of the odd, the weird, and the wonderful. The more we find, the less we know.

A journey through the cosmos in search of alien life. We seek out planets around distand stars and dive into the oceans of other worlds - seeking an answer to the question: is there anybody out there?

In the third episode, the discovery of extraterrestrial life might face an impossible challenge: the physics of the universe itself; but using cutting-edge tech, experts might be on the verge of a groundbreaking find -- and the evidence could already be in hand.

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.

Chris Lintott and Maggie Aderin-Pocock report on the reaction to the dramatic announcement of the discovery of phosphine gas in the clouds of Venus, a gas that could be a sign of life. Venus remains an inhospitable and unlikely host. But if not Venus, where in the solar system is the best place to look for alien life? Chris and Maggie investigate the latest missions to Mars and the icy moons of Jupiter and Saturn. Away from the search for life, Pete Lawrencepreviews the best meteor showers of the year.