Jonathan O'Callaghan

Jonathan O'Callaghan is a freelance space and science journalist based in London. He has written for The New York Times, Scientific American, and Wired, among other publications.

New York Public Library

Where Are All the Tiny Black Holes?

The discovery of a celestial “unicorn” that’s just a slim 2.9 solar masses may help unravel a mystery that has long puzzled astronomers.
- Jonathan O'Callaghan and Quanta Magazine
- January 30, 2021