Sagittarius A* : Black Hole at Centre of Milky Way
- 13 May 2022
- 4 min read
Why in News?
Recently, Scientists from the Event Horizon Telescope (EHT) facility, revealed the first image of the black hole named Sagittarius A* at the centre of our galaxy - the Milky Way.
- Nearly all galaxies have these giant black holes at their centre, where light and matter cannot escape, making it extremely hard to get images of them.
- Researchers called the black hole “the gentle giant in the centre of our galaxy”.
What does Black Hole Image Unveil?
- This image of the black hole referred to as Sagittarius A* (Sagittarius A(asterisk)) gave further support to the idea that the compact object at the centre of our galaxy is indeed a black hole.
- It is near the border of Sagittarius and Scorpius constellations. It is 4 million times more massive than our sun.
- It strengthens Einstein’s general theory of relativity that a point in space where matter is so compressed as to create a gravity field from which even light cannot escape.
- The researchers said that imaging Sagittarius A*, the black hole at the centre of the Milky Way, was much more difficult than imaging M87.
- In 2019, the Event Horizon Telescope made history by releasing the first ever image of a black hole Messier 87 (M87) – the black hole at the centre of a galaxy M87, which is a supergiant elliptic galaxy.
What are Black Hole?
- The concept was theorized by Albert Einstein in 1915 and the term ‘black hole’ was coined in the mid-1960s by American physicist John Archibald Wheeler.
- Usually, the black holes belong to two categories:
- One category ranges between a few solar masses and tens of solar masses. These are thought to form when massive stars die.
- The other category is of supermassive black holes. These range from hundreds of thousands to billions of times that of the sun from the Solar system to which Earth belongs.
- In April 2019, the scientists at the Event Horizon Telescope Project released the first-ever image of a Black Hole (more precisely, of its shadow).
- Gravitational waves are created when two black holes orbit each other and merge.
- A galaxy is a huge collection of gas, dust, and billions of stars and their solar systems, all held together by gravity.
- Earth is the part of the Milky Way Galaxy, which also has a super Massive Blackhole in the middle.
- There is a region of space beyond the black hole called the event horizon. This is a "point of no return", beyond which it is impossible to escape the gravitational effects of the black hole.
Event Horizon Telescope Project
- EHT is a group of 8 radio telescopes (used to detect radio waves from space) located in different parts of the world.