The spins of some early galaxies could be a clue that the entire observable universe exists within a black hole—except, that ...

Researchers have spent the past few years watching a black hole re-awaken roughly 300 million light-years away from Earth.

While solitary black holes should be common, they are hard to find. The one in Sagittarius revealed itself when it passed in front of a dim background star, magnifying the star’s light and slowly ...

"This pushes our models to their limits and challenges our existing ideas about how these X-ray flashes are being generated." ...