Could humans evolve on other worlds?
The early history of the Solar System contained collisions and explosions. We know that the age of the Earth is around 4.5 billion years old. It’s by coincidence that it is one-third the age of the universe. The EarthMoon system was most probably made by a collision and by an object the size of Mars.
For hundreds of millions of years many meteorites, asteroids and comets bombarded the Earth. Life would not have formed in these early times because our planet was too hot and dry, so there would have been no possibility of this.
At around the same time that the rocks stopped falling, the Earth started to cool down. The first signs of an ocean started to appear. We even have fossils that show evidence of life within a few hundred billions of years – that’s about the same time that life could have possibly occurred here. How life came to evolve on our planet is strong evidence that life can evolve elsewhere in the universe. Intelligent life – that’s us – has only really turned up quite recently.
We ourselves are made out of star material. Stars that explode send chemical material into space. Some of it is recycled and some of it travels outside of our galaxy to make the next generation of stars that could have planets – worlds that could be like Earth. So that’s the idea: stars explode and make future generations of stars and planets.
John Mather, an astrophysicist at NASA’s Goddard Space Flight Center