Astronomers have obtained the closest glimpse yet of the supermassive black hole thought to lurk at the center of our galaxy. They focused on radio emissions around the black hole over an area equal in width to the distance between the Earth and the Sun.

If astronomers are able to see up to the edge of the black hole’s event horizon — beyond which no light can escape — they may be able to determine whether Einstein’s theory of general relativity holds up under high gravity conditions.