Now and then there is a bright radio flash somewhere in the sky. It can last anywhere from a few milliseconds to a few seconds. They appear somewhat at random, and we still aren't sure what they are.

A new study has found that a hidden bias in galaxy models can skew gravitational-wave measurements of how fast the universe is expanding. That finding complicates one of astronomy’s most promising ...

Light released by a distant star does not simply wink out after crossing some threshold of space. In a vacuum, photons keep ...