Planetário do Porto: Supermassive Black Holes

Black holes are celestial bodies that capture everyone's imagination and curiosity. They come in various sizes, have different histories, and distort light, time, and gravity. They do not reveal what they do with everything that gets too close to their borders, making them a kind of mirror from “Alice in Wonderland”: everything “inside” is strange to common sense, governed by different rules. Nothing can escape these bizarre objects - not even light gets trapped, making them invisible. So how can we detect black holes and confirm their existence observationally?