Researchers have spent the past few years watching a black hole re-awaken roughly 300 million light-years away from Earth. And what they’ve documented challenges prevailing theories about black hole lifecycles. The groundbreaking observations are detailed in a study published on April 11 in Nature Astronomy.

"This rare event provides an opportunity for astronomers to observe a black hole's behavior in real time," said astronomer Lorena Hernández-García.

A massive black hole at the heart of a galaxy in the Virgo constellation is waking up, shooting out intense X-ray flares at regular intervals that have puzzled scientists, a study said Friday.