Sizes and Structures of Black Holes

There are four main sizes of black holes: micro, stellar-mass, intermediate, and supermassive. Micro black holes can only weigh up to the mass of the moon, and all are less then a 1/10 of a millimeter in diameter. These are results of colliding cosmic waves or even bombardment of particles in particle accelerator. Stellar-mass holes are formed by collapsed giant stars (info on collapsed stars here, and giant stars here). These black holes are typically under 10 solar masses and are about 30 km across. The next type, intermediate black holes, are formed when one black hole is swallowed by another, enlarging it. These black holes weigh up to a thousand suns! Finally, supermassive black holes are found at the centers of galaxies. These black holes began as quasars and weigh from 100,000 to a billion suns. These black holes are so large that the largest, if placed in the sun's position, would extend out to the orbit of Earth!!!!

Black holes have three main parts to them. The first and outermost is called the ergosphere. This only exists if the black hole has angular momentum (see types of black holes) . In this zone, it is impossible for any object to stand still. The spin of the black hole causes a tidal force that acts upon the gravity well, shifting it. The ergosphere is in the shape of an elongated sphere that is tangent to the outer event horizon. The outer event horizon is the point of no return. Nothing, not even light can escape once beyond this point. Since no light is emitted from this part of the black hole, nothing inside can be seen. But it is believed that inside, at the very center, is the singularity. The singularity is the star's core crushed to a point (or the case of a spinning black hole, a ring) so small that it must be magnified over a trillion times to view any structure. More on black holes here and here.