Black holes have always been some sort of an enigma for scientists, but just recently, they have been discovering more and more about them. A black hole is a place in space where the gravitational pull is so strong that even light can not get out. This occurs when matter has been squeezed into a tiny space; this causes the gravitational pull to be stronger than it usually is. This enigma has been given the name of the ‘black hole’ because it does not reflect or emit any light. The only moment they become visible is when they are feeding on stars or gas clouds that are close to their boundary; this boundary is called the ‘event horizon’.
Black holes are formed when a star dies which causes the star’s gravity to pull matter inward and compress its core. This makes the core heat up to such a great extent that it produces an explosion. After the explosion, only the highly compressed core is left; now called a black hole. The core is so strong that it sinks to the layers of time-space. The core becomes what we call ‘singularity’, and the opening of the black hole is called ‘event horizon’ which can also be called “the mouth” of the black hole. After an object passes the event horizon, it is lost forever and it is irretrievable.
There are three types of black holes: stellar, supermassive, and intermediate. Stellar black holes are the smallest, but the most dangerous kind. They are formed by the collapse of an individual star.
Supermassive black holes can be a billion times larger than our Sun. These black holes usually lie in the center of almost every galaxy, including the Milky Way. Scientists are not very sure how this type of black hole first forms; however, they speculate that they are the result of tiny black holes merging. Although, they could also be formed from large clusters of dark matter; nevertheless, this is just a theory as scientists still do not know what dark matter is composed of.
Intermediate black holes are those that are medium-sized like its name states. They are believed to form when stars, that are in a cluster, collide and cause a chain reaction. If several of these holes form in the same region, they could eventually merge and create a supermassive black hole. Intermediate black holes are the rarest type and are believed to only be found in dwarf or very small galaxies. Scientists have gathered hints that intermediate black holes exist; however, they haven't found one yet.
Black holes can not be seen by the naked human eye and because of this, scientists have to rely on being able to detect the radiation the black holes emit when dust and gas are drawn into them. In 2019, scientists took the first image of the black hole, M87, which is around 6.5 billion times the mass of the Earth’s Sun. This was accomplished by EHT ( Event Horizon Telescope) which is a team of around 200 scientists that had been working on this for around 2 decades. Even after the images were taken, the crew had to spend 2 years doing further research before being able to release them to the public. This was because they had to put together all the images that were taken across different observatories worldwide to then, build a replica of what the black hole looked like. Currently, ETH is working on capturing an image of Sagittarius A*, a supermassive black hole that resides in the Milky Way. But just like the black hole M87, it has proven tricky to get a clear picture as it lies within a large distance from Earth.
As demonstrated, black holes are a part of our universe that is still largely unknown. Technology is advancing every day; allowing us to discover and learn more about them. We hope that in the future we get to explore more in-depth what these phenomenons are, what allows them to form, and the dangers they could bring.
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