Astronomers find it by watching nearby stars and gas race in tight orbits around an unseen center, then using gravity to work out the mass. When gas falls inward, it forms a superhot disk that shines in X-rays, giving away the black hole's presence. Some black holes are found when they bend background starlight, or when they merge and send out gravitational waves.
Get more accurate answers with Super Pandi, upload files, personalized discovery feed, save searches and contribute to the PandiPedia.
Let's look at alternatives: