Sagitarrius A*: The supermassive black hole at the centre of our Milky Way
Do you remember Gargantua, the supermassive blackhole featured in the epic science fiction ‘Interstellar’, directed by Christopher Nolan? The fictional Gargantua was 100 million times that of the sun and 10 billion light years away from Earth. Recently, scientists have caught the glimpse of a real supermassive black hole lurking at the centre of our Milky Way, a large spiral of stars, dust and gas. It has been named Sagittarius A*. Simply put, supermassive black holes are the largest kind of black holes which have a billion times the mass of the sun.
What are black holes?
To understand the whats and hows of Sagittarius A*, you need to first know what a black hole is. Let’s make it easy for you. Black hole is a region of space from which nothing can escape, not even light. That is why it is invisible to human eyes. Only space telescopes equipped with specialised equipment are capable of spotting black holes. Additionally, special technologies can observe how stars in close proximity to black holes behave differently from other stars. Since matter has been compressed into a small region, gravity near black holes is extremely strong. This can occur when a star dies.
Features of Sagitarrius A*
Scientists from all over the world presented the first-ever photograph of Sagittarius A*, on May 12, 2022. The black hole has been termed “the gentle giant in the centre of our galaxy”. Well, the Event Horizon Telescope, a global network of synchronised radio observatories that work together to observe radio emissions related with black holes, has provided the historic image of Sagittarius A* (or Sgr A* in short).
Sagittarius A* is close to the Sagittarius and Scorpius constellations. Its mass is around is 4.6 million times greater than that of our sun. Sagittarius A* is located at a distance of 27,000 light years from Earth. The shadow of this supermassive blackhole is close to the size of a donut on the moon’s surface.
The findings of scientists suggest that Sagittarius A* is spinning and is more or less pointed towards us.
Sagittarius A* vs. M87*
Let’s take you back in time by a couple of years. Way back in 2019, a famous black hole was discovered in the M87 galaxy. The images of Sagittarius A* reveal that it is 1000x less massive than M87 * which, according to scientists, is about the size of the Munich football stadium. The environment of these black holes are also entirely different. While Sgr A* has been found at the center of our small spiral galaxy, M87* lurks at the centre of a giant elliptical galaxy. This giant black hole ejects a powerful jet of plasma too. Another interesting difference: Sgr A is * is 2000 times closer to the earth than M87*.