names distance why its popular size power when discovered size# Sagittarius A 26000ly local blackhole supermassive high 2022 10 M87 6.5mly emits fast particles supermassive high 2019 10 Cygnusx-1 unknown first proof they exist stellar blackhole high 1971 8 Gaia BH1 1500ly closes black hole stellar blackhole high 2022 6