From UPSC perspective, the following things are important :
Prelims level : Black Hole
Mains level : Black-hole theory and its relevance
- NASA released the first ever photograph of a black hole and its shadow.
Foremost thing: What is a Black Hole?
- A black hole is an object in space that is so dense and has such strong gravity that no matter or light can escape its pull. Because no light can escape, it is black and invisible.
- They drastically warp the fabric of space-time and anything that passes too close gets sucked into it be it a wandering star or a photon of light.
- They exist from the size of a human cell to more massive than the sun.
- Black holes of stellar mass are formed when a massive star collapses at the end of its life cycle.
- After a black hole forms, it continues to grow by absorbing mass from its surroundings.
Why a black hole was never photographed before?
- By definition, a black hole is a region in space where the pulling force of gravity is so strong that neither matter nor light can ever escape.
- For anything approaching a black hole, the point of no return is called the “event horizon”; anything that comes within the event horizon will be consumed forever.
- Because no light can escape from it, a black hole is invisible.
Then how it became possible?
- Advanced space telescopes can identify black holes by observing the behaviour of material and stars that are very close to black holes.
- The hot disk of material encircling a black hole, as NASA explained, shines bright.
- The gases in that accretion disk are heated up as they accelerate toward the black hole, causing them to glow extremely brightly.
- The colours they glow are invisible to us, but are detectable with an X-ray telescope.
- Scientists have also detected the gravitational waves generated when two black holes collide.
Black hole in Messier 87 (M87) galaxy
- The first photograph, which comes from the Event Horizon Telescope (EHT) project, shows the black hole that is at elliptical galaxy Messier 87 or M87.
- This black hole is 6.5 billion times the mass of the Sun. It is located some 55 million light-years from Earth.
- Catching its shadow involved eight ground-based radio telescopes around the globe, operating together as if they were one telescope the size of our entire planet.
About EHT Project
- The Event Horizon Telescope is a network of 10 radio telescopes on four continents that collectively operate like a single instrument nearly the size of the Earth.
- The EHT project is an international partnership formed in 2012. Its main objective is to directly observe the immediate environment of a black hole. T
- he findings will provide insight into the celestial object so dense that their gravitational field swallows everything including light.
What Einstein has to do with this mission?
- Einstein’s general theory of relativity predicts how space-time is warped by the extreme mass of a black hole, which he said has a mass that’s 7 billion times that of our sun.
- Einstein’s visions of a geometric bending of space and time first came to light in 1919.
- Overnight, Einstein became a household name.
- One hundred years later, Einstein’s theories were proven once again with this photograph – but instead of the sun, it was that of an elusive black hole.
- Science News’ magazine reported that the image aligns with expectations of what a black hole should look like based on that theory.