What are Black holes?
On May 12, 2022, in press conferences held around the world, astronomers revealed the first image of the black hole at the center of our Milky Way galaxy, of which our solar system is a part.
This image of the black hole, referred to as Sagittarius A* (SgrA*), gave further support to the idea that the object at the center of our galaxy is indeed a black hole.
It is located near the border of Sagittarius and Scorpius constellations and is 4 million times more massive than our Sun.
What exactly 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 gravitational pull. Since no light can escape, it is black and invisible.
- The event horizon is the boundary of no return at the edge of a black hole; any light or matter that crosses that boundary is sucked into the black hole. To escape, it would have to travel faster than the speed of light, which is impossible.
- Anything that crosses the event horizon is doomed to fall to the black hole’s core and be squished into a single point of infinite density known as the singularity.
The image 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. Albert Einstein theorized the concept in 1915, and the term ‘black hole’ was coined in the mid-1960s by American physicist John Archibald Wheeler.
A galaxy is a massive 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.
Black holes will emerge from the explosive demise of certain large stars. But some black holes are truly massive and are billions of times the mass of our Sun and inhabit the center of most galaxies. How these are found at galaxy centers is unknown. But it’s clear they energize the galaxy and will influence its evolution. By studying black holes, scientists can learn about the evolution of galaxies and perhaps even about the beginning of the universe.
This recent discovery was accomplished by the Event Horizon Telescope, a combination of eight widely spaced radio antennas to mimic a telescope the size of our planet. The same Event Horizon Telescope, in 2019, unveiled the first-ever photo (shadow) of a black hole residing at the heart of a different galaxy.