An astronaut on the International Space Station captured mysterious blue spheres in the sky last year. NASA’s Earth Observatory shared the photo last year, as well, shortly after it was taken.

many challenges exist for both building and finding such Dyson spheres, also called Dyson swarms. The idea behind a Dyson sphere is to collect as much energy from a star as possible. On Earth, the ...

Some of them had gravity so strong that it pulled them into spheres. And 4.54 billion years ago, our Earth was one of them. WATCH: Ancient Earth Was a Hellscape But this early Earth would have ...