Sagitarrius A* is a super interesting object in the center of our galaxy, and we have solid evidence that it weighs a lot: it is "supermassive" (about 4 million times more massive than the Sun), and is super dense. So, we've been assuming that it is a supermassive black hole, as all observations we've made support this.
However, it could be something more exotic, like a wormhole. That would be awesome, but it's hard to tell the difference from 26,000 light years away(ish). However, researchers at Fudan University have shown the next-generation of telescopes we're building should be sensitive enough and have enough resolution to do exactly this. Science fiction, my friends, is hopefully about to become science fact.
That raises an interesting question. If Sagittarius A* is a wormhole, how can astronomers distinguish it from a black hole?