Context:
A supermassive black hole at the center of a relatively nearby galaxy is taking bites out of a star similar in size and composition to the sun.
About Black Holes:
- A place in space, extremely dense where gravity pulls so much that even light cannot get out.
- The idea of an object in space so massive and dense that light could not escape it has been around for centuries.
- Most famously, black holes were predicted by Einstein’s theory of general relativity.
Types of black holes:
- Astronomers generally divide black holes into three categories
- Stellar-mass, Supermassive, and Intermediate-mass
- Cosmologists suspect a fourth type – primordial black holes
| Stellar | Supermassive | Intermediate | Primordial |
| Its mass can be up to 20 times more than the mass of the sun. There may be many, many stellar mass black holes in the Milky Way. | The largest black holes These black holes have masses that are more than 1 million suns together. Every large galaxy contains a supermassive black hole at its center. The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. | Size range between stellar and supermassive blackholes. These should range from around one hundred to hundreds of thousands of times the Sun’s mass. None have been identified with confirmation. | Theorize that primordial black holes formed in the first second after the birth of the universe. Scientists haven’t yet found definitive proof these primordial black holes ever existed. Theorized smallest black holes are as small as just one atom. These black holes are very tiny but have the mass of a large mountain. |
| How Do Black Holes Form? | |||
| Stellar black holes are made when the center of a very big star falls in upon itself, or collapses. When this happens, it causes a supernova. A supernova is an exploding star that blasts part of the star into space. | Scientists think supermassive black holes were made at the same time as the galaxy they are in. | Scientists think the smallest black holes formed when the universe began. | |
- The first black hole discovered was Cygnus X-1- located within the Milky Way.
- Terms related to black holes – Singularity, event horizon, accretion disc, relativistic jets, Schwarzschild radius, etc.
Source: The Hindu
Previous year question
Recently, Scientists observed the merger of giant blackholes billions of light-years away from the Earth. What is the significance of this observation?
[UPSC Civil Services Exam – 2019 Prelims]
(a) ‘Higgs boson particles’ were detected.
(b) ‘Gravitational waves’ were detected.
(c) Possibility of inter-galactic space travel through ‘wormhole’ was confirmed.
(d) It enabled the scientists to understand ‘singularity’.
Answer: (b)
