Another mystery of the universe is solved. 

We now know what a black hole actually looks like. 

You probably have seen this image from the National Science Foundation -- but here's why it's so significant.

black hole
Event Horizon Telescope

This black hole exists in a galaxy that's 55-million light years from Earth.

Scientists say this is something they thought would be impossible to see a generation ago.

This particular black hole has a mass that's nearly seven billion times more than the sun.

The amount of data gathered to show the black hole was so huge, it took half a ton worth of hard drives. That's a lot of selfies.

The image also confirmed Einstein's theory of general relativity, which described the nature of space, time and gravity.

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