Explore Black Holes
A black hole is not an object that pulls harder than other objects of the same mass. It is a region where mass has been concentrated into so small a volume that escaping from close to its centre would require exceeding the speed of light. If the Sun were replaced by a black hole of identical mass, Earth’s orbit would not change at all.
The five profiled below cover the range of what has actually been observed: the first object accepted as a black hole, the first one photographed, our own galaxy’s central engine, a system that erupts every few decades, and one of the most massive ever measured. Each page explains how we know what we know about it, and lists its sources.
