Sagittarius A*

About Sagittarius A*:

• It is a supermassive black hole at the Milky Way’s Center. 
• It was discovered in the 1970s.
• It is mostly dormant and only occasionally absorbs gas or dust, but nonetheless has an estimated mass 4.3 million times that of the sun.
• It is located in the constellation Sagittarius.
• It is a strong source of radio waves. Most of the radio radiation is from a synchrotron mechanism, indicating the presence of free electrons and magnetic fields.
• The event horizon of the black hole has a radius of 12 million km (7 million miles).

What is a Black hole?

• A black hole is a region in space where gravity pulls so much that even light cannot 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.