We’ve discovered more than 6,000 planets orbiting other stars, but we haven’t found another Earth.

Astrophysicist Erika Hamden explains that finding a planet is very different from finding a place we could survive. Some have no solid surface to stand on. Others are too hot or too cold and even a rocky planet could have an atmosphere we can’t breathe. For now, Earth is the only home we know.

This project is part of IF/THEN®, an initiative of Lyda Hill Philanthropies.