A black hole is an area of space where the pull of gravity is so strong that even light cannot escape. This happens when a large amount of matter occupies a small space.
A black hole is a small area of space where the strength of gravity is very high as there is a large amount of matter is squished into a very small space. Black holes are invisible. They can’t be seen, as any light or other types of electromagnetic radiation cannot escape from within. Scientists know that black holes exist from the effects that the large gravitational field has on the surrounding area. The term 'black hole' was coined by John Wheeler.
In 1783 John Michell first suggested that there could be a body in space that has a mass which is so large that even light would not escape. Einstein’s scientific revolution, his theory of relativity, changed the way we think and understand gravity. Einstein’s theories described gravity as the warping of spacetime and this encouraged scientists to think again about the possibilities of black holes. Using Einstein’s theory of relativity, Karl Schwarzschild calculated the radius of a sphere where, if all mass of the sphere were compressed into a small space, matter and light wouldn’t be able to escape. This boundary between where light can and cannot escape is known as the event horizon.
Most black holes are formed at the end of a star’s life. They occur when the core of the star collapses in on itself causes a supernova explosion. The Sun in our solar system will never turn into a black hole because it isn’t massive enough. Stars need to have a mass several times that of our Sun to form black holes. Black holes that are very large are known as supermassive black holes. These have a mass of one million times the mass of our Sun or more. Large galaxies are thought to have a supermassive black hole at their center. Observations of our galaxy, the Milky Way, have shown there is a supermassive black hole at the center.
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