In 2019, scientists achieved a great goal of astrophysics when they published the first-ever image of a black hole. By coordinating radio telescopes around the world to create, in effect, one Earth-sized telescope, scientists were able to capture an image of a black hole.

The image is an astounding moment for science, when an invisible phenomenon one trillion times more massive than Earth became visible.

The supermassive black hole lies at the center of the galaxy M87. But did you know that our own Milky Way galaxy also hosts a black hole at its center? It's the supermassive black hole known as Sagittarius A-star.

Thousands of stars collect in dense orbits around Sagittarius A-star. It's intense gravity actually pulls the fabric of spacetime toward its border, which is called the event horizon.

If a wandering star gets too close, it will begin to be pulled toward the event horizon, with no chance of escape. Under these conditions, whole stars and even the light they emit get consumed. 

The light that comes from the gas flowing into the black hole appears to wrap around the black hole's shadow, which allows us to photograph it, even though the thing itself is invisible.

But there are special difficulties when it comes to photgraphing Sagittarius A-star, even though it's much closer to home. Because we're inside the Milky Way, we can only peer at Sagittarius A-star through dust and gas that disturb radio observations.

If someday we devise a way to glimpse Sagittarius A-star, what will we learn about our galaxy or about the others with their own black holes at their centers?