Black holes are massive but only cover small areas, according to Space.com. Black holes have a powerful gravitational pull that makes it impossible for anything to escape, including light. Intermediate black holes can form together in the center of any galaxy and create supermassive black holes, while other black holes are the size of an atom.
NASA mentions that black holes form when the center of massive stars collapse from within. Black holes cannot be seen because the gravitational pull forces light into the hole's center.
Black holes are comprised of three layers that include the singularity and the inner and outer event horizons. The singularity is the point where space and time are concentrated, and it is the mass of the hole. The event horizon is the lining of the black hole's mouth where light is unable to escape.
A person falling into a black hole would become increasingly elongated and would die before reaching the singularity. Black holes do not exert suction; rather, objects fall into the holes due to the effects of gravity. Astronomers estimate that there are 10 million to 1 billion black holes with masses three times that of the Sun in the Milky Way. A black hole cannot swallow Earth because there is no black hole that is close enough to the solar system, and the Sun cannot turn into a black hole because it is not large enough.