Stephen Hawking is saying we need to colonize the Moon and Mars and fast.

"We are running out of space and the only places to go to are other worlds. It is time to explore other solar systems. Spreading out may be the only thing that saves us from ourselves. I am convinced that humans need to leave Earth," Hawking said, according to BBC.

The world renowned theoretical physicist noted that fighting climate change and global warming are still important goals, but that human space travel is key to "elevate humanity."

Hawking said that leading nations should send astronauts to the Moon by 2020, and plan to build a lunar base within 30 years. He added that people should be going to Mars by 2025.

"Spreading out into space will completely change the future of humanity," Hawking said. "I hope it would unite competitive nations in a single goal, to face the common challenge for us all."

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Stephen Hawking: 'I Am Convinced That Humans Need to Leave Earth' - Fortune