Everyday life at the University (black holes)

This morning I went to a lecture (computational physics) for the first time in 2.5 years, and after that (not in the course, but during a break) I learned a new fun fact: the black holes in the center of galaxies are not like "normal" black holes... 

I actually sort of thought that a black hole is a black hole - that they are just what you get when a really big star dies and collapses. But then I learned that the black holes in the center of all galxies - that we call "supermassive" black holes - are much bigger than the "normal" ones, and they can't be created by the collapsing of a star. Actually, we don't even know how they are created, we just know they're different...!

We do know they are huge, though; their masses are more than 1 million suns together; and the supermassive black hole at the center of the Milky Way galaxy (which is called Sagittarius A) has a mass equal to about 4 million suns - that's a lot ;)

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