Scientists from the Event Horizon Telescope (EHT) facility, revealed before the world the first image of the black hole at the centre of the Milky Way, Sagittarius A.

About Sagitarrius A

  • Sagitarius A (asterisk) near the border of sagittarius and scorpious constellations. 
  • Sagittarius A is 27,000 light years away from us. 
  • It is 4 million times massive than our sun.
  • The image of Sagittarius A, strengthened Einstein’s general theory of relativity by being precisely the size Einstein’s equations dictate. 
  • Sagittarius A is about the size of the orbit of Mecury around the sun.

What is a black hole?

  • A black hole is a region in space of so immense gravity that even light and matter cannot escape it. Light gets bent and twisted by gravity and then sucked in the abyss along with superheated gas and dust. Because no light can escape, it is black and invisible.
  • The boundary at the edge of a black hole is called the event horizon, which is the point of no return. It would need to travel faster than the speed of light to escape, which is impossible.
  • Anything that crosses the event horizon is sucked by the centre of the black hole and gets shoved into a single point with infinite density, called the singularity.


How do we photograph the invisible blackholes?

  • Looking at the effects of their extreme gravity, which pulls stars and gases toward them.
  • It is true that anything past the event horizon is invisible, but outside that boundary there is sometimes a spiral disk of gas which the black hole pulls towards itself but not still into itself completely
  • The heated gases glow extremely brightly. The colours are invisible to our normal eye but are detectable with an X-ray telescope.
  • Light surrounding the event horizon are also detected when gravitational waves are created with the clash of two black holes. 

About Event Horizon Telescope-

The Event Horizon Telescope (EHT) is a planet scale array of eight ground-based radio telescopes that operates together through international collaboration. Together they form an Earth-sized virtual telescope with unprecedented sensitivity and resolution.

Objective: This project was designed to capture black hole images, so that scientists get the opportunity to study extreme objects in the Universe predicted by Einstein’s theory of relativity.

Bodies involved: Thirteen partner institutions worked together to create the Event Horizon Telescope. Key funding was provided by the US National Science Foundation (NSF), the EU's European Research Council (ERC), and funding agencies in East Asia.

Technique Used: The EHT observations are based on a scientific technique called very-long-baseline interferometry (VLBI).

  • The first image that was released was of a black hole located in the center of galaxy Messier 87, in the constellation Virgo. 
  • It is located about 53 million light -years away from earth with a mass of 6.5 billion Suns.