Add Yahoo as a preferred source to see more of our stories on Google. Right above you is the sky – or as scientists would call it, the atmosphere. It extends about 20 miles (32 kilometers) above the ...

Observations show the universe appears flat, yet its true size and global shape beyond the observable horizon may remain forever unknown.

Michael S Turner argues that the next breakthrough in particle physics and cosmology may be just around the corner.

Why outer space systems need high power density. Why power-generation systems in outer space are important. Generating electricity at nighttime using renewable resources has become extremely important ...