Eli5: why are images of black holes so blurry and not better quality?


Eli5: why are images of black holes so blurry and not better quality?

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Because they’re very far away, and as we’ve got radio telescopes across the entire earth we’re already at maximum resolution.

For Sagittarius A* (the more recent image), you’ve also got to contend with the fact that you’ve got half the Milky Way in between earth and the black hole. This is why M87* was the first to be photographed despite being further away.

The only real way to improve resolution would be to place more telescopes in space, but you’d need a few.

They’re not in visible light. They’re radio waves.

They’re also images taken over a long period of time. We’re not talking minutes or hours here, we’re talking months. This means that the matter around the black holes is moving and it moves quite far during that time. This means that even if you could get a good resolution the images would still be blurred due to that.

They’re technically the sharpest resolution photos ever taken

There’s a physical limit to how sharp an image can be, related to the wavelength of light you’re observing at and the size of the collection area (satellite dish, camera lens, etc). They’re observing in radio waves but the dish is effectively the size of the earth which given them a resolution better than any camera or telescope ever

It’s blurry because even though the black hole is 25 million miles across, its 157 quadrillion (million billion) miles away, so it’s unbelievably tiny even with that resolution

Because how do you take a photo of a hole? It’s pretty difficult 😆