First, there was definitive proof of a black hole in the centre of our galaxy.

Then a group of scientists, including the incomparable Katie Bouman, managed to snap the first ever picture of a black hole.

Since then, our fascination with one of the most violent objects in our universe has grown.

The first thing you need to know about black holes is that they are really, really big – I guess the clue is in the word ‘supermassive’.

If we had to turn the earth into a black hole you’d have to shrink it to just 2,5 centimetres across.

In this sense, they’re kind of like the TARDIS in Doctor Who – bigger on the inside.

Business Insider notes that their secret weapon is gravity. The more mass you can shrink into a small space, the stronger your gravitational force will become.

The smallest are stellar black holes, which form after a giant star explodes and collapses in on itself, which measure about 64 km across. But in that small space is enough mass to equal 11 of our suns.

In another galaxy called M33, there’s a black hole that is almost 100km across and packs as much mass as 15.7 suns inside.

Up next are the intermediate-mass black holes. At 2,350km across, they can reach almost the same distance as it is from Cape Town to Bulawayo.  and according to some calculations, contains the mass of 400 suns.

None of these compares to supermassive black holes like Sagittarius A, which is smack bang in the centre of our galaxy.

It covers a region about 24.4 million kilometres in diameter. That’s roughly 168 Jupiters across, and inside is the same amount of mass as 4 million suns combined – still its small.

To get an idea of just how big supermassive black holes can get, watch this:

And there you have it. Stay away from the event horizon and everything will be fine.

[source:businessinsider]