In 2017, scientists at an observatory in Hawaii detected an interstellar object near Earth, which they named 'Oumuamua. The more scientists looked at it, the weirder it got - this cigar-shaped object didn't behave like any other asteroid or comet seen in our Solar System before. To Avi Loeb - the very eminent chair of the Harvard astronomy department - it felt like potential evidence of extraterrestrial intelligence and technology and when he said so publically, there was a media storm. No scientist had ever been prepared to go on record saying this before. In Extraterrestrial, Loeb explains what the extraordinary discovery of 'Oumuamua and the latest astronomical research means for our place in the universe as we know it. Through a fascinating tour of the universe from its earliest time, he reveals the latest scientific research into other probably Earth-like planets that could host life - and what this means about our place in the universe as we comfortably know it.