In simple language, black holes are dead stars. The term “hole” gives people a wrong impression; a black hole is definitely not an empty area in space. It is packed with large amounts of matter, almost ten times the size of our Sun compressed into a sphere the diameter of which is the same as that of New York City.
The death of any star does not result in the formation of black holes; only the death of a gigantic star creates a black hole. For a star to transform into a black hole after its explosion, it has to be at least ten times as huge as the Sun. When a massive–sized star dies, its nuclear fusion reactions stop. At the same time, its gravitational field starts pulling matter inward, compressing the star’s core and causing it to heat up. The result of excessive heating is a huge supernova explosion, in which the material and radiation blasts out into space.
What remains after this explosion is the highly compressed massive core, the gravity of which becomes so strong that even light cannot escape; this is what scientists call a “black hole”. Once a black hole is formed, it becomes too black to appear because it pulls all the light into its center; that is how it obtains its name.
Luckily enough, black holes do not move around in space swallowing the celestial objects they meet. Objects do not get sucked by black holes unless they are very close to it, at a place scientists call the “event horizon”. Stars close to black holes produce a high-energy light that can be identified using special satellites and telescopes.
However, black holes are just as hard to spot; as described by scientists, it is like photographing “an orange on the moon”. They can only spot black holes through observing the behavior of stars in space. That is why capturing an image of a star becoming a black hole has been a long awaited target by scientists and astronomy fans. On Wednesday, 10 April 2019, the National Science Foundation and the Event Horizon Telescope group revealed the first-ever recorded image of a black hole. The project is a global collaboration of more than 200 scientists using an array of observatories scattered around the world.
After the image was launched, it only took seconds for posts and memes to saturate social media. Such an achievement deserves to be hailed; not only for its uniqueness or for the efforts scientists exerted to capture it, but also for being a breakthrough that validates a pillar of science, the “Theory of Relativity”, which was put forward by Albert Einstein more than a century ago.
References
bibalex.org/SCIplanet/Spring2015.pdf
bibalex.org/SCIplanet/Cosmic Colors
nationalgeographic.com
nationalgeographic.com.au
space.com