Vox has a nice piece with some good videos describing how Astronomers just turned on a planet-size telescope to take a picture of a black hole .
Because Sagittarius A is so small, and surrounded by so much occluding material, it’s going to take a huge telescope to see it. According to Nature, it would take a telescope 1,000 times more powerful than Hubble to get enough resolution to see it.
So how does the Event Horizon Telescope solve this problem? Conventional optical telescopes use bigger and bigger mirrors to see objects smaller and farther away in the universe. The Event Horizon Telescope is doing something similar: It’s creating a virtual telescope the size of the entire Earth.
The Event Horizon team is connecting radio telescopes at eight locations across the world — as far-flung as Hawaii and the South Pole — and instructing them all to look toward Sagittarius A for a few days. The network is the result of an international collaboration of 14 research institutions across the world.