Re-arranging things a bit from the previous page, and substituting C for V:
R is called the Schwarzschild radius: it is the radius at which a certain Mass, ANY MASS, will by definition, be a Black Hole.
Anything that is not able to
stay in orbit and falls within the Schwarzschild Radius of the black hole,
will leave
this Universe forever. This is sometimes referred to as the EVENT HORIZON
because this boundary keeps us from viewing anything inside of this radius.
We are unable to see any light escape from within this radius, thus information
about what is occurring within this radius, so called events, are never known
outside of the Black Hole.
An object of ANY MASS can be a black hole, it just depends on what radius it is.
The Larger the Mass, the larger the radius, but they will all be Black Holes.
Typical Radii for Black Holes of Different Masses:
What would happen if the Sun (for some inexplicable reason) became a Black Hole?
What would happen to Earth?