The search for extraterrestrial life is one of the most exciting frontiers in astronomy. In this talk, celebrated astrophysicist Avi Loeb of Harvard University describes claims of tentative clues close to Earth: the weird interstellar object `Oumuamua and the cloud deck of Venus.

Loeb argues that our civilisation will mature once we find out who resides on our cosmic street by searching with our best telescopes for unusual electromagnetic flashes, industrial pollution of planetary atmospheres, artificial light, heat or artefacts, or something completely unexpected. We might turn out to be a form of life as primitive and common in the cosmos as ants are in a kitchen. If so, we can learn a lot from others out there.

• How to find ET: 7 ways aliens might give themselves away
   
• Are there any aliens out there? We are close to knowing for sure
   
• 7 things we thought were made by aliens, but weren't... probably
   
• Why icy moons like Europa are our best bet for finding alien life

Additional on-demand video content:

• Are we alone in the universe? by Sarah Rugheimer Astrophysicist, University of Oxford