What Happens to Stars Much Heavier Than The Sun?
STAGE 4b: Black Hole
If the central core, that remains after the supernova blast, is greater than 3 times the sun's mass, the internal pressure cannot halt the gravitational collapse. The core will continue to collapse to form a black hole.
In a black hole, there is so much mass compressed into such a small volume that gravity prevents even light from escaping. Since no light can ever reach your eyes from the collapsed core, it appears black, hence the name.
The apparent surface of the black hole is the radius at which light just manages to escape. It is called the event horizon.
For example, a black hole with 3 times the solar mass would have a circumference of 55.5 kilometers (the size of a town). The Earth as a black hole would only be a couple of centimeters in diameter (about the size of a marble)!