Thread by @NASAUniverse

Just because black holes don’t emit light doesn’t mean they’re totally invisible to us. By studying hints that point to their existence, we can learn a lot about them! Follow this thread and read more here: tmblr.co/Zz_UqjZ-7BiySm… #BlackHoleWeek⚫ 1/6

One thing black holes can’t hide is their gravity. They affect their environment just like anything else in the universe that has mass. 2/6

For decades, scientists have tracked stars orbiting the black hole at the center of our galaxy. Using those observations, they’ve estimated the black hole holds 4 million times the mass of our Sun! 3/6

When stuff gets too close to a black hole, it gets pulled in and forms a debris disk. As the disk churns, its matter heats up and emits light, making it especially bright in X-rays. Some matter may even be shot out at high speed as a jet of particles. 4/6

The case for black holes was already pretty strong through indirect clues like these, but then a few years ago @LIGO started detecting the wiggles in space-time caused by merging black holes which was the first direct evidence of black holes merging! 5/6

As if that wasn’t enough, in 2019 the @ehtelescope released the first image of the shadow of a black hole! This was our first focused look at the region around a black hole’s event horizon. 6/6