What is Sagittarius A* (Sgr A*)?

About Sagittarius A* (Sgr A*):

• It is a supermassive black hole located at the center of the Milky Way Galaxy.
• It is located in the constellation Sagittarius.
• It has a mass equivalent to four million Suns.
• It has a diameter of around 5 million kilometers .
• It is mostly dormant and only occasionally absorbs gas or dust.
• The event horizonof the black hole has a radius of 12 million km.

What is a Black hole?

• A black hole is a region in space where gravity pulls so much that even light can not get out.
• The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.
• Because no light can get out, it is difficult to detect a black hole.
• The largest black holes are called "supermassive." These black holes have masses that are more than 1 million suns together.
• Albert Einstein first predicted the existence of black holes in 1916, with his general theory of relativity.

What is the ‘event horizon’ of a Black hole?

• It is the boundary defining the region of space around a black hole from which nothing (not even light) can escape.
• The escape velocityfor an object within the event horizon exceeds the speed of light.
• The radius of the event horizon is called the Schwarzschild radius, after the German astronomer Karl Schwarzschild.