Astrophysicist Stephen Hawking says that we’ll have settlements on the moon ‘within 50 years’ and thinks people will be living on Mars by 2100.

Speaking at the Live from Space program, he said failing to colonize new planets could lead to the extinction of humans, because the Earth will eventually become overpopulated.

The 72-year-old said that this ‘century will go down, in the history of humankind, as the true Space age.’