Another category of black hole is called ‘Stellar’. Its mass can be up to 20 times more than our Sun. Those black holes which are found largest by our scientists are called ‘Super Massive Black holes’. These super massive black holes have masses that are more than 1 million Suns pooled together. Scientist believes that there is a super massive black hole in centre of every galaxy including our ‘Milky way’. The super massive black hole at the centre of ‘Milky Way’ galaxy is called ‘Sagittarius A’. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million earths.
NASA is using satellites and telescopes that are traveling in space to learn more about black holes. These spacecraft help scientists answer questions about the universe. All common sense of physics like Newton's laws are simply thrown out of the window because Black holes completely distort time and space. As scientists get closer and closer to understanding the physics behind the Black hole, many equations are starting to not make sense anymore because the physics of Black holes are simply impossible to calculate perfectly. Some scientists believe it’s possible that black holes are ‘Worm Holes’ in Space: doorways to other points in the universe, or even other universes. But if you think about it, even if you made it in alive, it’s not clear how you’d escape the door on the other side, since this would be a Black Hole too.