What Is A Black Hole?

A black hole is a region of spacetime that nothing, including light, can escape. It is impossible to see a Black Hole because they are Black, but people still believe they exist even though you can't see them.

If a supergiant star explodes into a supernova, the leftover core forms a black hole. This has such a gravitational pull that it pulls everything within a certain distance into it even light. Black holes cannot be seen because the light itself gets sucked into it.

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A region of space resulting from the collapse of a star

In general relativity, a black hole is a region of space in which the gravitational field is so powerful that nothing, not even light, can escape. The black hole has a one-way surface, called an event horizon, into which objects can fall, but out of which nothing can come. It is called "black" because it absorbs all the light that hits it, reflecting nothing, just like a perfect black-body in thermodynamics. Quantum analysis of black holes shows them to possess a temperature and Hawking radiation.

Despite its invisible interior, a black hole can reveal its presence through interaction with other matter. A black hole can be inferred by tracking the movement of a group of stars that orbit a region in space which looks empty. Alternatively, one can see gas falling into a relatively small black hole, from a companion star. This gas spirals inward, heating up to very high temperatures and emitting large amounts of radiation that can be detected from earthbound and earth-orbiting telescopes. Such observations have resulted in the scientific consensus that, barring a breakdown in our understanding of nature, black holes do exist in our galaxy.
                                                                                    By Somrat Dutta
        

Giant star explosion