# Black hole photography

I recently read an article that said that the event horizon telescope took a picture of a black hole (Sagitarius A*) and it will be presented on the 10th of April. I was wondering how this picture is taken and what a picture of a black hole even means?

The only explanation I could think of was that the telescope took pictures of the stars surrounding the black hole and then a sudden absence of stars pointed that a black hole is present.

Can anyone explain how black hole photos are taken or how does event horizon telescope work?

• In order to be able to resolve something this small so far away, the signals from many telescopes across the Earth need to be combined to have as large an effective baseline as possible. The black hole has about 4 million solar masses, so its event horizon has a radius of about $10^{10}$ meters. It is about 8000 parsecs from us, which is more than $10^{20}$ meters. So its angular size in the sky is only about $10^{-10}$ radians. – G. Smith Apr 5 at 20:37