View a flash tutorial on the Anatomy of a Black Hole.
There are two main processes constantly going on in massive stars: nuclear fusion (which tends to blow the star's hydrogen outward from the star's center) And gravity (which tends to pull all hydrogen back in the direction it had come). These two processes balance one another until all the star's hydrogen is exhausted, allowing gravity to take over. Once gravity dominates, the star becomes unstable and starts to collapse. More massive stars tend to burn hotter and faster. Once all the hydrogen has been exhausted, such stars quickly collapse, shedding much of their mass in dramatic explosions called supernovae. Once the star starts to collapse, it does not stop, and the star (and ultimately its atoms) will cave inward upon itself, resulting in the formation of a black hole. Our sun Black hole candidate Earth Stars must be at least 3 times as large as our own sun before they will collapse into a black hole. Stars smaller than that will collapse into either a neutron star or a white dwarf. A black hole is defined, as a region where matter collapses to infinite density, and gravity so extreme that even light cannot escape. So if light is not given off by black holes, how do we detect them? Can you spot the black hole? Black holes can be detected through a technique called gravity lensing. Gravity lensing occurs when a massive object, in this case a black hole, passes between a star and the Earth. The black hole acts as a lens when its gravity bends the star's light rays and focuses them on the Earth. From an observer's point of view on the Earth, the star would appear to brighten.
Go to Anatomy of a Black Hole to learn more.
