Humans must leave Earth in the next 200 years if we want to survive.
That was the stark warning issued by Professor Stephen Hawking in the months before his death today at the age of 76.
The legendary physicists believed that life on Earth could be wiped out by a disaster such as an asteroid strike, AI or an alien invasion.
He also warned over-population, human aggression and climate change could cause humanity to self-destruct.
He believed, if our species had any hope of survival, future generations would need to forge a new life in space.